104612422 Conserving Historic Buildings

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CONSERVING HISTORICBUILDINGS

UCD School of Architecture, Landscape and CivilEngineering

A project submitted

to

University College Dublin

by

Group 10: DECLAN MORRISSEY, BARRY MURPHY, PAUL MURPHY, SINEADMURPHY, ORLAITH OBRIEN, MARK OCONNELL (Group Leader), DARRAGH

OGORMAN, NOEL MORAN, THOMAS OBOYLE

14 April 2008


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Executive Summary

This document reports the findings of 9 Bachelor of Engineering students on the subject of

the conservation of historic buildings. This is an important topic for Irish engineers, especiallythose who work in the cities of Ireland where many historic structures (facing reuse,

demolition or dereliction) can be found. This report attempts to identify some key areas of

building conservation and investigate the existing literature to gain an understanding of the

current status of building conservation. Then proposals are made for further research or

amendments to current methods wherever possible.

Firstly, the importance of conserving historic buildings is explained and the term historicbuilding is defined. It is investigated how a structure takes on this title and who is responsible

for the conservation and maintenance works on historic buildings. The causes of decay in

historic building are identified in order to gain an understanding of why buildings do not last

indefinitely. The causes of decay are numerous and are examined in turn along with the

associated risks, and a solution is proposed where possible. The impact that building

conservation and rehabilitation has on modern society is discussed and it is argued that it is a

positive impact as they preserve the culture and historical traditions of an area which

encourages a sense of unity among the local people. Dublins Smithfield is taken as a case

study.

To begin the examination of structural aspects of building conservation, foundations are

investigated. The problems that occur in foundations are addressed and various underpinning

remedies are reviewed. The main restriction on the foundation repair techniques is the fact

that the historic building being repaired must be preserved, meaning that less invasive

techniques are preferred. Old stone, brick and mortar walls are also researched. Stone was the

main building material used in Ireland from neolithic times right up to the beginning of the

twentieth century; it has withstood the test of time. Despite being an excellent building

material, stone is still vulnerable to weathering especially in modern cities with high levels of

pollutants. Having both aesthetic and structural qualities, it is important that sufficient care be

taken when restoring brick and stone walls. More decorative structural elements are also

examined domes, arches and beams. Engineers of the past used such ornamental features on

many significant buildings so they make up an important part of building conservation.


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Introducing modern building services into a historic building for the purpose of conservation

poses many problems and difficulties. A balance must be sought so that the aesthetic and

cultural integrity of the building is preserved, while still providing up-to-date utilities for the

building and its occupants. With the recent emphasis on reducing the energy consumption of

domestic buildings, which currently consume approximately 25% percent of the energy

consumed in Ireland and Britain, it is becoming necessary to investigate the potential to

reduce the carbon footprint of older housing stock which constitutes a large proportion of

housing. As the last part of this report, to help keep historic buildings viable in the modern

world, their environmental impact and ways of reducing this are investigated


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Table of Contents

1. CONSERVING HISTORIC BUILDINGS: AN OVERVIEW 1

1.1 Introduction 21.2 Defining a historic building and the importance of their conservation 21.3 Laws and legislation established to protect/conserve historic buildings 41.4 Role of the engineer in building conservation 51.5 Benefits of being a protected historic building and the role of the pwner 61.6 Conclusions 61.6 References 7

2. CAUSES OF STRUCTURAL DECAY IN HISTORIC BUILDINGS 82.1 Introduction 92.2 Literature review 9

2.3 Climate causes of decay 92.3.1 Solar radiation 92.3.2 Temperature and thermal expansion 102.3.3 Moisture and precipitation 102.3.4 Frost and snow 102.3.5 Wind 112.3.6 Natural disasters 11

2.4 Botanical and biological causes of decay 112.4.1 Botanical causes of decay 112.4.2 Biological and microbiological causes of decay 112.4.3 Fungal decay 11

2.5 Insects and other pests as causes of decay 122.5.1 Deathwatch beetle 122.5.2 Carpenter ants 132.5.4 Termites 13

2.6 Anthropogenic causes of decay 142.6.1 Vibration 142.6.2 Water abstraction 142.6.3 Atmospheric pollution 14

2.7 Internal environment of historic buildings 152.7.1 Moisture content of air 15

2.7.2 Heat and humidity 152.7.3 Ventilation 152.7.4 Lighting 15

2.8 Conclusions 162.9 References 16

3. RESTORATION OF HISTORIC BUILDINGS FOR MODERN USE 173.1 Introduction 183.2 Literature review 183.3 The role of rehabilitation in society 193.4 The rehabilitation process 19

3.5 Case study: Smithfield 213.5.1 Original site 213.5.2 Historic features retained 21


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3.5.3 Engineering techniques 223.6 Conclusions 233.7 References 24

4. FOUNDATIONS 25

4.1 Introduction 264.2 Literature review 264.3 Foundations and their importance in building conservation 27

4.3.1 Foundations in historic buildings 274.3.2 The importance of foundations in building conservation 28

4.4 Assessing problems with foundations of historic buildings 284.4.1 Foundations problems and the need for repair 284.4.2 Assessment of foundations 28

4.5 Repair of foundations in historic buildings 294.5.1 Mass concrete underpinning 294.5.2 Pier-and-beam underpinning 294.5.3 Pile-and-beam underpinning 304.5.4 Pile underpinning 304.5.5 Review of methods of underpinning 31

4.6 Conclusions 314.7 Recommendations 314.8 References 32

5. RESTORATION OF OLD STONE, BRICK AND MORTAR WALLS 335.1 Introduction 345.2 Literature review 345.3 Causes of decay in old walls 35

5.3.1 Characteristics of construction 355.3.2 Type of stone/brick used in construction 365.3.3 Environmental factors 36

5.4 Materials and methods used in the repair of old walls 365.5 References 37

6. BEAMS, ARCHES AND DOMES 396.1 Introduction 406.2 Literature review 406.3 Domes 40

6.3.1 History of domes 40

6.3.2 Problems with domes 416.3.3 Rectifying problems with domes 42

6.4 Beams 436.4.1 History of beams 436.4.2 Problems and solutions with beams 436.4.3 Problems with reinforced concrete 43

6.5 Arches 446.5.1 History of arches 446.5.2 Problems with arches 446.5.3 Rectifying problems with arches 44

6.6 Case study: The Mostar Bridge 45


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7. BUILDING SERVICES IN CONSERVING HISTORIC BUILDINGS 477.1 Introduction 487.2 Literature review 487.3 Heating services in conserving historic buildings 48

7.3.1 Primitive forms of building heating 487.3.2 Requirements and general considerations for installing a

heating system49

7.3.3 Plant and delivery system considerations 497.3.4 Dispersal units 50

7.4 Electrical services in conserving historic buildings 517.4.1 Primitive electrical installations 517.4.2 Electrical survey 51

7.4.3 Choice of cables for new installations 527.4.4 Practical considerations for electrical installations 52

7.5 Conclusions and recommendations 537.6 References 54

8. MODERN MATERIALS IN THE CONSERVATION OF HISTORICBUILDINGS

55

8.1 Introduction 568.2 Literature review 568.3 Modern materials 56

8.3.1 Aluminium 57

8.3.2 Modern materials in protection from earthquakes 578.3.3 Polymers 58


9. ENVIRONMENTALLY FRIENDLY AND SUSTAINABLE BUILDINGCONSERVATION

61

9.1 Introduction 629.2 Literature review 629.3 Windows 629.4 Insulation 63

9.4.1 Insulation of walls 639.4.2 Insulation of lofts 649.5 Case study 649.6 Summary and conclusions 659.7 References 66

10.CONCLUSIONS 6711.RECOMMENDATIONS 69


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1. Conserving historic buildings:An overview

B. Murphy1

1Year 2 Bachelor of Engineering Student,School of Architecture, Landscape and Civil Engineering,

University College Dublin, Belfield, Dublin 4.

Abstract. This chapter explains the importance of conserving historic buildings

and what we mean when we use the term historic building. It explains how a

structure takes on this title and what advantages this allows to the building. Then

it explains the roles of different areas of the community and their relation to the

topic of historic building conservation; the Irish government and its legislation,

the role of the proprietor in regards to maintenance and the role of the engineer

when working on renovation or restoration projects.


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1.1. Introduction

We are all familiar with the term historic building, an expression which creates images of

Dublin Castle, the Four Courts and the Customs House. However, it is not widely known

what the definition of a historic building is, or indeed how a building comes to have such a

status. This chapter attempts to address these issues and thereby provide a context for the

entire report. A brief look is also taken at building conservation and with whom the

responsibility falls in making sure these buildings are properly maintained for future

generations. It is also shown how being a registered protected historic building will invariably

extend the life of the building. After reading this chapter, it is hoped the reader will have a

better understanding of the importance of defining historic buildings and the value of their

prolonged conservation.

1.2. Defining a historic building and the importance of their conservation

When dealing with issues relating to Historic buildings it is important to first be able to define

exactly what a historic building is. We must be able to acknowledge exactly what constitutes

a historic building, what roles and functions it incorporates, and hence why there is a need to

conserve them. We can broadly define a historic building as one which is recognized as being

of particular architectural or historic interest; a Listed Building or a building of local

importance included on a local list (1). They are protected structures, buildings that a local

authority considers to be of special interest from an architectural, historical, archaeological,

artistic, cultural, scientific, social or technical point of view (2). They are everyday reminders

of the history of a great city, such as our own, Dublin. The GPO evokes images to us all of

one of the most important times in our countrys history.

Historic buildings are inarguably engraved in our past, as the name suggests, but they also

serve an important role in modern times. They help shape the cities in which they are situated,accentuating the diversity and uniqueness of the areas around them. They are a constant

reminder of how a location has developed and to lose them would be to lose part of the soul

of the city. They may also portray certain architectural and engineering qualities which

defined an era, such as the Georgian houses around Leeson Street (see Fig. 1.1), the Customs

House (see Fig. 1.2) or Christ Church which dates back to the 11th century. Failure to

conserve such buildings would lead to an extinction of evidence of these past times and the

undoubted architectural merits and examples of early engineering techniques which

encompass them.


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Fig. 1.1. Leeson Street, Dublin 2.*

Fig 1.2. The Custom House, Custom House Quay, Dublin 1.*

*Photographs by Mark OConnell


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According to a conference article written by Ingmar Holstrom, historic buildings should be

conserved for future generations by respecting the original building, an antiquarian demand

meaning that any intervention of the building should be done using original materials or those

closest to them, while not damaging other aspects of the building. All interventions should

also be minimal, reversible and recorded (3).

Holstroms words clearly indicate a need for these buildings to be maintained and conserved

and to be kept relevant in the 21st century. They should not be allowed to become derelict due

to neglect or replaced for financial gain. This responsibility is often placed upon us as

engineers but is also the duty of the owner, the government and wider community.

1.3. Laws and legislation established to protect/conserve historic buildingsThe Irish government, as an elected body representing the people, has a duty to protect

important historic buildings by passing and upholding laws which ensure their conservation.

Measures are put in place to create a clear process for buildings to become protected historic

buildings and laws are passed to make sure this title has great significance. The legislation

relates mainly to strict planning permission rules when the building in question needs to be

altered or when ownership is changing hands.

Every planning authority is obliged to have a Record of Protected Structures (RPS). Buildings

are proposed for inclusion in the RPS by elected members of the planning authority.

Subsequently the owners, occupiers, Minister for Environment and Local Government must

be notified of the proposal. The proposal is presented to the public and any queries or

concerns may be raised over the following six weeks. The elected members of the planning

authority then have a further twelve weeks to come to a unified decision, one which reflects

the comments of the public. If they decide to make the building a protected structure, the

owner and occupier must be notified within two weeks. This process was established under

the Local Government (Planning and Development) Acts from 1963 to 1999. All these acts

have now been consolidated under part IV of the Planning and Development Act 2000. It

reads:

For the purpose of protecting structures, or parts of structures, which form part of

the architectural heritage and which are of special architectural, historical, archaeological,

artistic, cultural, scientific, social or technical interest, every development plan shall include a


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record of protected structures, and shall include in that record every structure which is, in the

opinion of the planning authority, of such interest within its functional area.(4)

They are legally protected from harm and all future changes to the structure are controlled and

managed through the development control process (for example, planning permission) or by

issuing a declaration under Section 57 of the Planning and Development Act 2000. These

laws warrant that the building is now safe and will not be sacrificed. Should an investor

attempt to buy the property with the aim to demolish it, rebuild on the land and make a quick

profit, they would find it impossible to push the planning permission through the system.

1.4. Role of the engineer in building conservation

Engineers are often allocated the responsibility of conserving historic buildings. Urgent

renovations to old historic buildings require specific engineering techniques if they are to be

undertaken adequately such as if the roof needs to be replaced or an aspect of the building has

become structurally weakened. Jobs such as these require a great deal of care, making sure

large-scale renovations do not damage the historic building in question. This is where

engineers come in. For example, if a load bearing wall needs to be replaced (having lost its

structural integrity over the years) an engineer will have the duty to manage the replacement

safely. Engineering techniques such as underpinning (see Section 3.5) may need to be used to

give temporary load relief to the structure. Underpinning techniques may also be used to

improve the foundations if the originals are deemed to be inadequate, or if some nearby

construction threatens to compromise them.

Engineers can also enhance a historic building (see Chapter 9 for environmentally

friendly enhancements) thereby guaranteeing it will be conserved even under modern day

conditions. Historical structural members can be strengthened to carry increased loading,

degraded timber, brick and stone (see Chapter 5) structural elements can be restored to theiroriginal properties and flood control measures can be installed where there are inadequate

draining systems. Modern building services (see Chapter 7) can also be incorporated if the

historic building is to be turned into a museum or tourist center. However all these works

must be done without damaging the buildings defining characteristics and this is the

responsibility of the acting engineer. Engineers play a huge part in the conservation of historic

buildings in developing cities.


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1.5. Benefits of being a protected historic building and the role of the owner

As a protected structure a lot of the responsibility in ensuring adequate conservation to the

historic building falls upon the owner. The owner must guarantee that no element of the

historic building which contributes to its special interest is endangered in either the short or

long term. If the building is kept in a habitable condition and regular maintenance is carried

out the building should not be in danger of becoming derelict or damaged. Planning

permission regulations are very specific when relating to protected historic buildings.

Changes to the property which would usually not require planning permission, such as interior

painting, has to be approved by the planning authorities as even these minor works may alter

the intrinsic, material qualities of the building. An owner may apply in writing to the

authorities if unsure of what works may be carried out. A declaration, under Section 57 of the

Planning and Development Act 2000, will be issued within twelve weeks of the request

stating what works may be carried out without planning permission. This may be appealed by

the owner to An Bord Pleanla. More extensive works are also under stricter scrutiny than

with regular buildings as the application must include an extensive and highly detailed list of

drawings, photos, plans and documents which leave no doubt that the works involved will not

compromise the character of the historic building. If the building is becoming endangered the

planning authority can intervene by serving a notice to the owner that certain works must be

carried out. A conservation grant scheme has been established to assist the owner in

undertaking these necessary works. The standard figure is 50% of the cost of works (up to

13,000) or 75% (up to 25,000) in exceptional circumstances. In the event that the owner

refuses to complete the renovations, the law grants special power to the planning authorities.

They may complete the works themselves or in extraordinary cases may buy out the property

by compulsory purchase if they deem this to be necessary for the buildings conservation.

There are also possible penalties for non-compliant owners or those who knowingly allow the

structure to be endangered as stated in the Planning and Development 2000. If found guiltythey could serve a term of imprisonment or incur a fine of up to 1.27 million.

1.6. Conclusions

This report has given an overview of the topic of Conserving Historic Buildings, acting as a

general introduction to the report. It has clearly defined what a historic building is and the

reasons why they should be conserved. They are soaked in tradition, culture and society and it

would be a shame to allow them to pine away in the face of heartless urban development. Itwas found that engineers, the government and the owner all have their place in the


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conservation project. The government has a responsibility to provide ample protection for

these protected structures by using the judicial system and by enforcing laws for the benefit

and betterment of the buildings. The owner of any such building also has to accept the

responsibility that they are in possession of a structure of national significance and make sure

any works or renovations required are satisfactorily seen to. Finally, any engineer working on

a project dealing with the conservation of a historic building has a professional duty to

complete the works with the utmost care and minimal disruption to the structure. In

conclusion the conservation of historic buildings is an important issue controlled by laws

which must be adhered to by all involved parties.

1.7. References

(1) http://www.torridge.gov.uk/onlineplan/written/cpt28.htm

(2)http://www.environ.ie/en/Heritage/ArchitecturalProtectionandHeritagePolicy/PublicationsDocuments/FileDownLoad,3498,en.doc

(3) Conference Article written by Ingmar Holstrom at conference in Sweden entitled ToBuild and Take Care of What We Have Built with Limited Resources, CIB 83, The 9th CIBCongress. Volume 4: Building Materials and Components.

(4) http://www.irishstatutebook.ie/2000/en/act/pub/0030/sec0051.html#partiv

(5) www.dublintourist.com

(6)http://www.citizensinformation.ie/categories/housing/building-or-altering-a-home/protected-structures

(7) http://www.leemccullough.ie/renovation/index.html


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2. Causes of structural decay in historic buildings

T. OBoyle2

2

Year 2 Bachelor of Engineering Student,School of Architecture, Landscape and Civil Engineering,University College Dublin, Belfield, Dublin 4.

Abstract. In conserving historic buildings it is important to know how decay

might come about, how it affects the building and what intervention is needed to

save the building. The causes of decay were researched using books, internet

databases and journals. These are climate, the affect of seismic zones, botanical,biological and microbiological causes of decay, insects and pests, anthropogenic

causes and internal environment of historic buildings. Each of these is examined

in turn as well as the associated risks, and a solution is proposed where possible. It

was found that some causes of decay are far more harmful than previously

expected. This research indicates that the internal environment of historic

buildings needs more research as the type of damage associated with it can

ultimately destroy the building in question. An increase in inspections done for

this type of damage is recommended, as many old buildings have poor ventilation.


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2.1 Introduction

Conservation of buildings in an extremely important matter and although gravity is one of the

principal causes of structural decay, the causes of decay which shall be detailed in this chapter

have a huge influence on structures. These should give a varied outlook onto the decay in

historic buildings and generally aid the process of conserving building. It is clear that it is

impossible to conserve building without knowing sufficient information.

2.2 Literature review

Feilden (2003) was an extremely useful resource as it offers a broad approach to examining

the causes of decay in historic buildings, and thus provided a context for this chapter.

Beckmann and Bowles (2004) provide an insight into the vulnerability of materials in historic

building. It discussed the damages these materials incur and suggested possible (through

reinforcement etc.). OCofaigh et al. (1996) was useful for the section on the internal

environment. It addresses in detail the affect of heat and humidity on the indoor environment.

The Met ireann website (http://www.meteireann.com/climate) provided vital statistics for

this chapter to highlight how rain statistics need to be gathered in order to conserve a building

properly, as rain can cause certain materials to dissolve. Furuno et al. (2004) highlights the

extreme danger of termites. Huge amounts of research are done into termite damage and this

article shows this. It also offers a solution to this type of decay.

2.3 Climate causes of decay

Climate, in all aspects, is one of the fundamental causes of decay of buildings. It causes

materials to fail which affects the structure. The resistance of building materials to climatic

agents of decay increase with age and exposure thus this becomes a problem for historic

buildings. Thus the site needs to be examined before any conservation work is undertaken.

2.3.1 Solar radiation

Solar radiation is the prime cause of climate conditions. Different materials vary in there

ability to absorb wavelengths of solar radiation. Dark materials absorb more heat than others.

Materials vary from being a good absorber to being a good reflector. Ozone, water vapor,

clouds and dust restrict the amount of solar radiation. A climatologist measures this using a

radiometer. Shown are values gathered that a conservation architect or engineer needs when

working
http://www.meteireann.com/climatehttp://www.meteireann.com/climate


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Table 2.1: Global Solar Radiation in Joules/cm2 for Dublin Airport

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

2008 7050 13090 26830 10420 - - - - - - - - 64469

2007 8076 12672 26685 49222 53834 45900 8739 40987 30376 19118 8342 6553 350504

(Source: http://www.meteireann.ie)

Light, especially the UV component is a destructive agent especially to organic materials such

as wood and causes fading, embrittlement and loss of substance. The cause of air temperature

change is done by the sun, radiation through day and convection by night. Shaded parts of

building arent liable to damage, only being affected by the seasonal average temperatures.

2.3.2 Temperature and thermal expansion

All materials expand and contract with heat which causes damage. The extent of thermal

movement depends upon the temperature change, the thickness, the conductivity and

coefficient of expansion of the material. Temperature induces stresses into buildings. This

produces cracks on materials which can result in failure. The internal temperature of stone

fluctuates a lot so this needs to be considered.

2.3.3 Moisture and precipitation

The presence of water in any form causes or accelerates the decay of most materials. Faultydisposal of rain water is the most frequent cause of deterioration in ancient masonry. Moisture

causes condensation which is more dangerous than water as it takes in the gaseous pollutants

and suspended dirt which affects a building. Charts, graphs and research must be done to

monitor the rainfall. These are important statistics as the type of material in a certain place

needs to be considered as rainfall can cause serious damage. Table 2.2 is the type of statistic

that Conservation Engineers and Architects need:

Table 2.2: Total rainfall in millimetres for Dublin AirportJan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

2008 97.4 14.7 101.8 7.9 - - - - - - - - 221.8

2007 73.2 77.8 38.8 14.7 35.0 126 127 95.5 39.2 15.7 53.8 63.8 761.0

Dissolved salts in materials can be damaged by rain and moisture. Salt can be carried by rain

and where there is heavy rain, especially in coastal areas, this can be a serious problem.

2.3.4 Frost and snow

Frost is a serious condition where buildings are concerned. But it is not extreme cold that

causes damage to buildings as much as frost changes - the actual process of freezing and
http://www.meteireann.ie/http://www.meteireann.ie/http://www.meteireann.ie/


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resultant expansion of ice and subsequent contraction on thawing. The depth of foundation

should be depth enough to avoid heave or expansion which causes the sub-soil to move with

consequent damage. Freezing damages porous building materials such as bricks and stone

through expansion. The weight of snow damages part of buildings like roofs, and gutters.

2.3.5 Wind

Wind doesnt need to be considered unless the wind blows at high speeds. Coastal areas are

subject to this as they get extremely high winds. Winds can also be dangerous as they can

pick up grit and pieces of material and gusts can rotate materials at high speeds and drill it

into buildings. Dust disfigures the exterior and interior of historic buildings. The eroding

action of wind combined with sand and dust can ultimately destroy massive buildings. Indeed

the most serious effects of wind pressure are found in conjunction with rain.

2.3.6 Natural disasters

Natural disasters cause a huge amount of destruction to historic buildings and these includes

seismic sea waves, tidal waves, landsides, volcanic eruptions, cyclones, hurricanes, tornadoes,

avalanches and snow slips. These need to be seriously considered depending on the location

and individually assessed. They are unpredictable and difficult to assess. Lightning is the

most frequent of natural disasters and usually strikes the top of buildings. Earthquakes are

disasters that cant be controlled. Inspections of vulnerability should be done on target

buildings and reinforcement or addition of members should be done if needed.

2.4 Botanical and biological causes of decay

2.4.1 Botanical causes of decay

Ivy, creepers and other plants can cause damage if allowed to grow freely. Ivy is dangerous as

it digs into crumbling masonry and causes disintegrated. Stonecrop, wallflowers, trees and

bushes should be taken care of. But these can be dealt with weed killers and such treatments.

2.4.2 Biological and microbiological causes of decay

Bacteria and lichens cause decay by producing acids which react chemically with the

structural material. Algae, moss and lichens grow on brick and stone which allow more

damaging plants to grow, through moisture. Lichens are made of certain algae and fungi

which can reproduce on moist external surfaces. Toxic washes can kill these.

2.4.3 Fungal decay

Fungi, mildew, moulds and yeasts do not need sunlight to grow. They depend upon organic

material such as plant life for their energy. Fungal attack occurs in well seasoned wood wheredamp conditions prevail. Adequate water and oxygen supply, suitable temperature and space


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to grow are the basic requirements for survival. Corners and poorly ventilated areas are

targets. Soft wood and a musty smell can indicate attack. The most common forms of fungi

are:

Dry rot and

Wet rot

Dry rot fungus (see Fig. 2.1) is serious as it can manufacture and carry its own moisture and

thus attack wood. This fungus grows from a spore and through its hair-like growth forms a

snowy-white growth. They like unventilated voids such as linings to walls but growth can be

slowed down by low temperatures. The cellulose is its food. When inspecting and controlling

this, identifying the starting point is vital. The best way to stop it is by removing the affected

area. Sterilization by chemicals and the use of high and low temperatures are also solutions.

Figure 2.1. A wood support infected by dry rot fungus

Wet rots are much less serious than dry rot as they do not carry their moisture with them so

their range can be found. The most common type is cellar fungus and it requires 25%

moisture content before it will attack. The ends of timber beams are vulnerable to this.

2.5 Insects and other pests as causes of decay

All buildings and materials are subject to attack by animals and pests, especially birds and

pigeons. Obvious methods such as spikes and cages can be used here to protect the building

but in the chapter we will be discussing insect attack.

2.5.1 Deathwatch beetle

The deathwatch beetle is one of the major enemies of historic buildings, as its favorite food is

oak, the principal structural timber of old buildings. They bore a hole and lay up to 400 eggs.

Eradication is done by drilling holes in the timber and filling them with preservative so thelarvae can be reached.


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2.5.2 Carpenter ants

The carpenter ant attacks exposed timber and can be noticed because of their loud buzzing.

They bore out large tunnels and an egg is laid in each cell and provided with food in the form

of pollen. Eradication is done by an annual paint of creosote or a thick lime wash coat.

2.5.4 Termites

Termites, of which there are two types (ground termites and drywood termites), can cause

sever damage to timber structures (see Fig. 2.2).

Figure 2.2. Damage that termites can cause.

Ground termites live in large colonies in the earth depending on source of moisture. There

are two main types of ground-dwelling termites are of concern and these are differentiated by

the way they digest the cellulose in the wood. They will die if denied access to their

underground home. Seal up any holes cut as these are prime spots for termites. It is necessary

to poison the earth below the building with a strong dose.

Drywood termites like to feed on seasoned wood. Their attack is more or less confined to thesapwood. Mounds of dust and heaps of excreta pellets are the only evidence of attack. Small

amounts of poison can be used on these as they digest each others food. With drywood

termites, authorities need all the help they can get as drywood termites are air-borne.

Fumigation is done by covering the area with a tent.

A solution to this problem is using insoluble metaborates in wood. Its done by impregnating

the wood with borax and metallic salts the metaborate and research shows that the treated

woods showed generally show little decay and termite resistance (Furuno et al., 2004) .


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A lot of research has been done into termites and pests in general and this is something that

should not be taken lightly as pest and insects can ultimately destroy a building.

2.6 Anthropogenic causes of decay

Man-made causes of decay are complicated and have widespread implications on historic

buildings. Little is being done to prevent these yet they are very important.

2.6.1 Vibration

Damage by vibration is one of the main man-made causes of decay. Ground transmitted

traffic vibration particularly that from heavy diesel vehicles is a serious problem. It causes

loss of structural strength in the superstructure through additional stresses and cracking.

Traffic vibration and pile driving cause the most damage to historic buildings, where vibration

is concerned, and the best way to resolve this is to remove the source.

2.6.2 Water abstraction

Water abstraction can be extremely damaging especially if its done for industrial purposes. It

caused Venice to sink and is affecting other cities such as London. This can cause differential

loading on foundations inducing stresses on buildings. To ease this new machines exist to

obtain the water and new codes exist.

2.6.3 Atmospheric pollution

Atmospheric pollution is the by-product of industrial and commercial activities, heating and

traffic. Pollution control is an important factor in preventing damage to our cultural heritage.

The greatest part of the pollution of the atmosphere arises from the burning of fuel in boilers,

furnaces, domestic fires and in internal combustion engines. Carbon dioxide occurs naturally

being given off by all living organisms as a product of respiration, as well as being a product

of artificial combustion of fuel. It is capable of dissolving limestone made of calcium

carbonate by converting into calcium bicarbonate, Ca(HCO3), which is water soluble.Sulphur dioxide occurs as a man-made by product, although quite significant amounts occur

by natural means. Its present in oils and coal and emitted quite heavily through diesel-engine

vehicles. Ozone is created in the upper atmosphere by the action of ultraviolet radiation on

oxygen its created through complicated chain of reactions resulting in the formation of ozone

and proxy acyl nitrate (PAN). It causes metals to corrode rapidly. Carbon monoxide, nitrogen

dioxide, chlorides, asbestos, beryllium and mercury are pollutants that each affect and

promote decay on buildings. They cause rust and decomposition. With stone, pollution


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generally dissolves stones. Its protected using lime but this doesnt last. Wood, bricks, tiles,

terracotta and glass arent too affected as long as theyre treated right.

2.7 Internal environment of historic buildings

2.7.1 Moisture content of air

Moisture exists in the air and in most building materials except metals, glass, paint and

plastics. Also occupants produce this as well. Moisture can also be produced by evaporation

from indoor plants, by direct or indirect infiltration of rain water and dampness.

2.7.2 Heat and humidity

Low relative humidity cause damage to objects in a building. It dries out materials and

promotes cracking. High relative humidity promotes growth of mould and attracts insects.

Heat in a building is gained from the occupants and other things like electric lighting and

solar energy. All in all, good insulation, thermal mass and permeability to moisture are

beneficial.

2.7.3 Ventilation

Stagnant air creates condensation which leads to dampness and this leads to outbreaks of rot.

Old buildings generally have no mechanical ventilation so natural ventilation is important.

Windows are important for this. The stack effect can be used here. Cold air enters at low

levels and pushes warm air out at high level outlets through the use of pressure. (This is

reversed during the summer). The bigger the openings, the more the wind flow. Air

conditioning units can be used but these can be damaging to an old building.

2.7.4 Lighting

For natural lighting, windows are crucial and the placement of them needs to be carefully

considered. There are three important aspects of the natural lighting of a building. First, the

window/wall ratio in relation to thermal mass. Second, heat loss and air infiltration caused by

windows. Third, the danger of unwanted thermal gain from sunlight, particularly as UV raystends to damage buildings. These contribute significantly to affecting the internal

environment. Artificial lighting produces radiation and heat which is dangerous but this can

be solved using low heat fluorescent tubes. Also flashes used in photography can cause drying

in wood and other materials due to its radiant heat so the area in question may need to be

protected.


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2.8 Conclusions

The causes of decay listed above have a significant affect on historic buildings. Their impacts

on historic buildings can be devastating if left unchecked. The solutions proposed in this

chapter must be implemented if any of the symptoms described are observed. It is

recommended that there be an increase in inspections and intervening action taken where

necessary. With historic buildings, it is important to identify problems early and prevent the

development of decay, as often it is impossible to fully restore the true nature of a building

which has succumbed to decay.

2.9 References

Beckmann, P. & Bowles, R., (2004). Structural aspects of building conservation. Oxford:

Butterworth-Heinemann

Feilden, B. M., (2003). Conservation of Historic Buildings. 3rd ed. Oxford: Architectural

Press

Furuno, T., Lin, L. & Katoh, S., (2004). Leachability, decay and termite resistance of

wood treated with metaborates. Journal of Wood Science 49 (4), p.344-348

Met ireann website, http://www.meteireann.ie [accessed 13 April]

OCofaigh E., Olley, J. & Lewis J.O., (1996). The climatic dwelling: an introduction to

climate-responsive residential architecture. London: James & James Science Publishers Ltd.
http://www.meteireann.ie/http://www.meteireann.ie/


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3. Restoration of historic buildings for modern use

O. OBrien3

3Year 2 Bachelor of Engineering Student,School of Architecture, Landscape and Civil Engineering,

University College Dublin, Belfield, Dublin 4.

Abstract. This chapter discusses the impact that rehabilitation has in modern

society. Through extensive research it was found that it has a positive effect as it

preserves the culture and historical traditions of an area which encourages a

sense of unity. From a financial point of view it was also discovered that

rehabilitation is advantageous as it reuses capital and resources which already

exist. This means that the cost of demolishing and rebuilding an entire new

structure is compensated for. The process of undertaking a rehabilitation project

was also explored as there are many guidelines that must be followed in order to

protect historical buildings and their heritage. It was discovered that tax

incentives are offered by the government to encourage rehabilitation. However,

it is difficult to preserve classic buildings while still adapting them for use in

todays society. This balance is hard to find but is possible as demonstrated in

the case study of Smithfield, where the Jameson Whiskey Distillery was

founded in 1780. This site is a prime example of how rehabilitation should be

done it rejuvenated the area, giving it a modern purpose in the economy and at

the same time retained many of the features that make it a unique place. The

designers cleverly used the heritage of the area to their advantage by featuring a

museum on site which highlights the original use of the site as a whiskey

distillery. Two hotels were also included in the development and Smithfield is

now one of the top tourist attractions in Dublin city.


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3.1 Introduction

The previous chapter gave you an outline as to why historic buildings need conservation. This

chapter sets out to find equilibrium between history and the modern world we live in. Historic

buildings are present in most major cities around the world and have a particular prominence

in Dublin. Beautiful buildings, such as the Customs House (built 1791) and Dublin Castle

(built 1208-1220), are a reminder of what came before us and are important in our heritage

and cultural identity. However, not every building over one hundred years old can be

preserved exactly how it is; a city must still grow and develop with the culture of the time. It

is natural to adapt old buildings for contemporary use as otherwise a city would become stale

and decay. This process is called rehabilitation and defined as:

The act or process of returning a property to a state of utility through repair oralteration that makes possible an efficient contemporary use, while preserving those features

of the property significant to historical, architectural and cultural values.

(Dept of Cultural Affairs, Nevada, 2002)

The subsequent chapters will deal with the structural aspects of conserving historic buildings

whereas this chapter focuses on the steps of rehabilitation and the significant role engineers

have in it. They are the back bone of any construction project; however dealing with historic

buildings is a much more difficult challenge. Engineers are responsible for the structural

integrity of the building but they must also realise its cultural importance and take appropriate

care when planning. The stages of rehabilitation will be outlined and then highlighted through

a detailed case study on the Smithfield area; the redevelopment of the abandoned Jameson

Distillery into a museum, a music studio, two hotels and numerous apartments transformed

the region from desolate to thriving. Nevertheless the true spirit of the area was maintained

through innovative design and the understanding of the historical value of Smithfield.


Feilden (2003) presents a broad approach to building conservation and provided base reading

for this chapter, discussing the idea of historic buildings and their conservation.

Barrett and Kennedy (1999a) and Barrett and Kennedy (1999b) detail the rehabilitation of the

Smithfield area in Dublin, which together give an excellent example of a successful

rehabilitation project undertaken in recent times.


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The rest of the information for this chapter was gathered from many websites of Dublin-based

public bodies and tourist information organisations.

3.3 The role of rehabilitation in society

The presence of a historic landmark in an area is often an underappreciated gift. Living in a

country as culturally rich as Ireland might cause people to take advantage of the wonderful

structures that surround them. However, these buildings are a testament to our heritage and

are what bring us together as a community. There is a sense of pride and identity as a result of

the history that was made in buildings like the G.P.O (built 1818) or the skill in designing the

stunning Christ Church (todays structure built from 1871 to 1878).

These factors are all down to the rehabilitation of historic buildings. Places like Temple Barand UCDs very own Newstead underwent rehabilitation to make them what they are today.

Notable buildings like these were made useful in todays society yet still maintained their

heritage. In most cases rehabilitated buildings are brought back from the brink of death to find

a new life and purpose. The Department of Environment, Heritage and Local Government has

emphasised in its report Architectural Heritage Protection Guidelines for Planning

Authorities that it is beneficial for historic sites to be kept in use rather than left to

deteriorate. The Government even gives tax incentives to those who take on the challenge of

rehabilitation. The Historic Area Rejuvenation Plan was also started by Dublin City Council

in 1996 (after the Smithfield Village development began) in order to promote conservation of

historic buildings and encourage private development on derelict sites. These measures were

taken because the Government is aware of the positive impact rehabilitation has on society. It

rejuvenates areas that are neglected and decaying and in many cases the revitalised area

prospers as tourists come to share the unique culture. Hence without the rehabilitation of

countless historic buildings our world would be a much more depressing place.

3.4 The rehabilitation process

Rehabilitation is a multi-faceted issue and so it needs a multi-disciplinary team. This is

especially important for historic structures as there are even more factors to consider due to

their age and importance. According to Feilden (2003) the following people, at least, should

be included in a team for a thorough rehabilitation:

Civil engineers Historic architects Town Planners Landscape architects Quantity surveyors Urban planners


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Traffic Managers Development economists Health officers

It is the opinion of the author that adding project managers, historians and archaeologists to

the team would make it even more capable of handling historic rehabilitations. Each

professional is responsible for different aspects of the development but all are important in

order to stay true to the history of the building. For example, the civil engineers job is to

guarantee that the historic building remains structurally reliable. On the other hand, the

historic architect is responsible for the architectural history of the building. Skill and

understanding are essential to completing the project with appropriate consideration.

The keys to any good development are organisation and communication. Therefore thespecialised group should meet regularly so that there is complete and accurate communication

within the team. They must first of all establish their priorities the most important of which

is preserving the historic attributes of the building. The next step is one of the most vital

stages in the rehabilitation process the survey. A thorough survey must be done on the

historic building to analyse its condition. Precise detail is required when dealing with old

structures as they may have deteriorated over the years due to lack of maintenance. The

survey will determine the moisture content of supports and any structural work or repairs that

are required to bring the building up to date with the present building regulations. The specific

regulations for a building depend on its use and hence the new function of the building must

be defined once the survey is evaluated. This decision requires research to be done into the

previous uses of the building; as Feilden (2003) stated, the team must work with history, not

against it. It is generally advised that the rehabilitation keeps the modern use of the building

as similar to the original as possible. This means less interference and change to the landmark

and so preserves its historic elements. From a financial point of view it also reduces costs as

altering the use may require expensive structural work, such as floor strengthening, to be

done. However, old buildings do have a lot of scope for modernisation as they often have

large, spacious rooms that are easily adapted. Nevertheless, respect for the rareness of ancient

buildings is a big part of completing the transformation from past to present. In an ideal

rehabilitation skilled members of the team would identify the special features of the building

which make it unique. It is then up to the architect and engineer to design the rehabilitation

around those extraordinary characteristics.


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3.5 Case study: Smithfield

3.5.1 Original site

In 1995 the Smithfield Village development got underway when the developers Heritage

Properties Ltd applied for planning permission for a vast rehabilitation. The 85m x 125m site

(approx.) is located in the whole area surrounded by Bow St, New Church St, Smithfield and

Friary Ave as you can see from the map in Figure 3.1 below.

Figure 3.1: Smithfield site Figure 3.2: Smithfield under construction

Architects A. & D. Wejchert and Barrett Mahony Consulting Engineers were hired for the

task of transforming the abandoned whiskey distillery into a modern village with modern

facilities that still remained true to its original purpose. The distillery was originally built in

1780 and, along with the local markets it made Smithfield a very prosperous area. After the

distillery closed in the 1970s the area suffered and the old distillery was subjected to

vandalism and disregard.

3.5.2 Historic features retained

Throughout the site it is clear that a conscious effort was made to ensure that the uniqueness

of Smithfield remained. Along Bow St and New Church St the original stone walls were kept.

Also the 9 storey tower and 3 chimneys were maintained and incorporated into the design.

Unfortunately, in some situations preserving everything just as it was did not work and so

alternatives had to be devised. In one case a red brick wall was carefully taken down and

erected in a different place on the site. This is slightly controversial as according to

Architectural Heritage Protection Guidelines for Planning Authorities the recycling of

historical materials confuses the history of the building. However, seeing as the bricks were

reused in the same site I believe that the site retains its integrity. The designers merged the

past and present in another innovative way by incorporating the 3 storey red brick wall that


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faces onto Smithfield plaza into the entrance to one of the hotels. They preserved the majority

of the 1895 wall as it was and cut high vertical slots into it to allow light and access into the

hotel behind. This is easier to understand from Figure 3.3 below.

Figure 3.3: Red brick wall Figure 3.4: Inside the museum Figure 3.5: Turret roofs

The special characteristics of Smithfield were also reflected in other aspects of the

development. Duck Lane which runs through the site from Bow St to Smithfield is an

imitation of a lane which existed when the distillery was active. The turret roof design of the

apartments (seen in Figure 3.5 above) is also intended to represent the roofs of the kilns that

were used in the whiskey making process.

The museum built into the development was an excellent way of showcasing the special

features of the distillery. The brick vats used to store the whiskey were carefully restored andare now on show for tourists. Also two original timber trusses (which can be seen in the top of

Figure 3.4) stretch the length of the reception and were perfectly conserved. They now

support a new mezzanine from which visitors can look down to the glass covered ground

floor where the retained old foundations and brick lining structures are clearly visible. Figure

3.4 again emphasises this inventive design.

3.5.3 Engineering techniques

As in most rehabilitations extra effort and skill is required by the engineer as dealing with

historic buildings can be difficult. However the engineers on this development rose to the task

very well when faced with tricky problems. One issue was the very old tower on site which

restricted access during construction. This matter was solved by carefully taking it down and

rebuilding it in the exact same place when the rest of the work was completed. Another 1813

chimney had to have its foundations encased in concrete so that it was not destabilised by

excavations for an underground car park nearby. The largest chimney in Smithfield was alsopreserved because the 42 metre high structure is a dominant feature in the skyline. It was


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converted into a viewing tower which boasts a 360 view of Dublin. Even though it was built

in 1895 an inspection showed that the red brick was in good condition. However the cast iron

plate which covered the rim at the top had been damaged by corrosion and weather. This was

replaced with a re-enforced concrete capping which was inventively shaped using the restored

cast iron plates as formwork. As its new purpose required it to support a lift and additional

weight the chimney needed to be strengthened and its wind resistance increased. This was

done by spraying a re-enforced concrete lining on the internal walls to form a stiff diameter

pipe which transfers the stresses down through the length of the tower. The spiral staircase up

to the viewing cap goes down through the chimney and was anchored into the brick wall. The

finished product can be seen below in Figure 3.6 (a) with the lift shaft on the left.

(a) (b) (c)

Figure 3.6: Views of Smithfield

3.6 Conclusions and recommendations

From the points discussed above it is clear that rehabilitation of historic buildings is a

necessary action in order to revitalise structures and areas that were once active parts of the

community. It is important that these buildings become integrated into modern society byadapting them for use again. This process may be more difficult than a regular development

but it is unreasonable to build entirely new buildings whilst disused historic buildings

deteriorate. There are many guidelines available which underline the important factors to

consider when taking on rehabilitation. The case study detailed in this report is an example of

a very successful rehabilitation of a group of historic buildings which make up old Jameson

whiskey distillery in Smithfield. The rehabilitation has updated the buildings to give them

purpose while staying true to the history of the site. The entire area has been lifted as a result

and it is once again a thriving community in the heart of Dublin city centre.


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3.7 References


Press

Barrett, V. & Kennedy, C. (1999a). The redevelopment of the Jameson distillery site, The

Engineers Journal, Vol 53, pp. 9-19.

Barrett, V. & Kennedy, C. (1999b). Smithfield Village - The redevelopment of the Old

Jameson distillery site. Presented to a meeting of the Structures and Construction Section of

the IEI, 3rd February.

Department of Environment, Heritage and Local Government, www.environ.ie,

[accessed 5 April 2008]

Dublin City Council, www.dublincity.ie, [accessed 10 April 2008]

Dublin Tourist information, www.dublintourist.com, [accessed 22 March 2008]

Department of Cultural Affairs, Nevada (2002), State Historic Preservation Office,

http://dmla.clan.lib.nv.us/docs/shpo/poguide/guide6.htm, [accessed 18 March 2008]

Map of Smithfield area, www.google.com/maps, [accessed 20 March 2008]

National Inventory of Architectural Heritage, www.buildingsofireland.ie, [accessed 9

April 2008]

Jameson Whiskey, www.jameson.ie, [accessed 11 April 2008]
http://www.environ.ie/http://www.environ.ie/http://www.dublincity.ie/http://www.dublincity.ie/http://www.dublintourist.com/http://www.dublintourist.com/http://dmla.clan.lib.nv.us/docs/shpo/poguide/guide6.htmhttp://dmla.clan.lib.nv.us/docs/shpo/poguide/guide6.htmhttp://www.google.com/mapshttp://www.google.com/mapshttp://www.buildingsofireland.ie/http://www.buildingsofireland.ie/http://www.jameson.ie/http://www.jameson.ie/http://www.jameson.ie/http://www.buildingsofireland.ie/http://www.google.com/mapshttp://dmla.clan.lib.nv.us/docs/shpo/poguide/guide6.htmhttp://www.dublintourist.com/http://www.dublincity.ie/http://www.environ.ie/


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4. Foundations

M. OConnell4

4


Abstract. The purpose of this chapter is to outline the various types of

foundations that may be found in historic buildings, and then to examine the

methods of assessment and repair associated with these foundations. This is done

by examining basic texts on the subject of building foundations and integratingthis information with that of texts more concerned with the holistic concept of

conserving historic buildings in general. In this way, an understanding of

foundation repair may be cultivated in such a way as to be sympathetic to the

requirements of historic building conservation. Foundation maintenance is an

integral part of building conservation, because if done properly, it can save costs

by preventing the need for further repair work on damages resulting from

differential settlement. Indeed, it is of paramount importance that a building is

well founded before any superficial restoration works are considered.


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4.1. Introduction

A foundation is basically the widening of the bottom of a vertical element in such a manner so

that the allowable bearing pressure of the soil on which it sits is not exceeded, and hence the

building does not sink or move. This can be achieved by the simple widening of the base of a

wall, or the digging of a trench, filling it with concrete and building on top of that.

Hodgkinson (1986) points out that modern foundation design and geotechnical engineering

has only been developed relatively recently and that there are many intriguing foundation

types to be observed in buildings of the late nineteenth century (see Section 3.3.1). With this

in mind, it is no surprise that many historic buildings require foundation maintenance and

repair in order to avoid excessive movement of the buildings, and hence prevent damage to

the buildings both structurally and aesthetically.

4.2. Literature review

Perhaps due to the fact that building conservation requires unique solutions for every case or

maybe because it straddles a fine line between civil engineering and architecture, much of the

literature produced in this area seems to have a slightly vague, discursive nature and tends to

avoid putting forward any exact techniques or methods. This lack of prescriptive guidance is

also prevalent in the specific area of foundation repair, but this could be explained by the fact

that although foundation repair is relatively straightforward, its application in individual

situations depends on many factors such as the historic building in question, the existing

foundations of the building, or indeed the infinitely many different soil conditions that may

exist.

Conservation of historic buildings

Feilden (2003) presents a broad approach to building conservation, which is slightly lacking

in technical information, but does include a dedicated section on foundations with well-known interesting case study examples. BS 7913:1998 lays out widely accepted guidelines for

the conservation of historic buildings. Although neither of these texts is particularly

prescriptive, together, they provide a context for the discussion of foundations in this chapter.

Fundamentals of foundations

Hodgkinson (1986) provides a comprehensive overview of foundation design in buildings

including, most notably for this chapter, sections on underpinning, foundation hazards andrelated construction problems.


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Foundations in historic buildings

Hodgkinson (1986) briefly discusses the kinds of foundations that have been used in building

construction in the past.

Assessment of foundations

Feilden (2003) identifies some key factors that should be included in the assessment of

foundations in historic buildings. The Building Research Establishment (1993) discusses the

investigation of buildings which may require underpinning, and describes the kinds of

problems that occur with foundations as well as the possible causes of these problems.

Foundation repair or reuse

The Building Research Establishment (1993) gives a concise guide to the process of

underpinning, identifying the reasons for underpinning and the methods used. This is a core

idea in this chapter.

4.3. Foundations and their importance in building conservation

4.3.1. Foundations in historic buildings

Hodgkinson (1986) gives some examples of rudimentary foundations built many years ago

which are still in service today. These include walls merely resting on the soil, widened early

strip footings and even some timber piling arrangements (see Fig. 4.1).

Figure 4.1. Old types of foundation still giving service today

(Source: Hodgkinson, 1986)


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4.3.2. The importance of foundations in building conservation

Foundation maintenance and repair are perhaps the most important aspects of building

conservation. It is important that underpinning or any foundation repairs are undertaken, if

necessary, before any other restoration work is done or any damage repaired (Building

Research Establishment, 1993).

4.4. Assessing problems with foundations of historic buildings

4.4.1. Foundation problems and the need for repair

The two main causes of problems with foundations are identified in Building Research

Establishment (1993) as settlement and subsidence. Settlement is described as downward

movement brought about by the pressure from a foundation causing compression of thegroundthe differential settlement of one part of a building relative to another that produces

distortion and cracking and subsidence is defined as downward movement of the ground

brought about by removal of water from the ground, excavation, soil erosion etc..

Foundation repair is generally only necessary if further undesirable movement of foundations

needs to be stopped. There is little point in modifying the foundations of a building in which

undesirable movement has occurred and has finished more than 50 years ago (unless ofcourse, a significant change of use is planned, or excavation works are being considered

nearby). Therefore, it is important to assess whether or not the movement is continuing.

4.4.2 Assessment of foundations

The first and quickest way to identify foundation problems is to look for severe cracking of

walls and finishes. Then any cracks found would be fitted with strain gauges to see if the

movement is ongoing. The movement of the building itself can also be measured using plumbbobs, theodolites and similar equipment. It is noted by Feilden (2003) that it is highly

desirable to measure alterations in the level of the water table. This is because a change in

the water table (possibly due to water extraction, see Section 2.6.2) may very well alter the

allowable bearing capacity of the founding soil.

It is also important to accumulate as much information about the building as possible, such as

plans or drawings if available or indeed if they exist at all. As Feilden (2003) points out, these

may reveal something of vital importance such as whether or not timber piles are involved. If


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this is the case, the possibility of decay (see Section 2.3.3) in the piles must be considered,

especially if there has been variation in the level of the water table. This, in turn, complicates

the assessment of the foundations as timber is a far more variable material than either of stone

or concrete. A Dutch study (Sass-Klaassen et al., 2007) has found however, that although

timber piles are not generally suitable samples for testing, dendrochronological dating and

provenancing (i.e. identifying the age and origin of the timber) of the piles is possible to a

reasonable extent. This allows more inferences to be drawn regarding the reliability of the

foundations.

4.5. Repair of foundations in historic buildings

The method of underpinning is described by the Building Research Establishment (1993) and

is presented here. In general, underpinning involves the extension of foundations downwards

to reach stiffer or more stable ground. There are four main types of underpinning:

Mass concrete

Pier-and-beam

Pile-and-beam

Pile

4.5.1 Mass concrete underpinning

This involves excavating systematically (see Fig. 4.2) in adjoining bays beneath the existing

foundation, filling the excavations with concrete and then pinning-up the small gap between

the old and new foundations.

Figure 4.2. Mass concrete underpinning

(Source: Building Research Establishment, 1993)

4.5.2 Pier-and-beam underpinning

A reinforced concrete beam is installed in the wall, either just above the existing footing orreplacing it, and discrete pits are excavated at intervals beneath the modified wall. After


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filling the pits with concrete to form piers, pinning-up is carried out between the concrete and

the base of the beam or existing foundation as with mass concrete underpinning (See Fig.

4.3).

Figure 4.3. Pier-and-beam underpinning


4.5.3 Pile-and-beam underpinning

Piles are installed beside the walls and beams are inserted, both within the walls and through

them, to join the tops of the piles (see Fig. 4.4).

Figure 4.4. Pile-and-beam underpinning


4.5.4 Pile underpinning

There are various ways piles can be used in underpinning, but the type most relevant to

repairing the foundations in historic buildings would be where piles are installed through

holes drilled in existing foundations (see Fig. 4.5).


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Figure 4.5. Pile underpinning

(Source: Building Research Establishmen,1993)

4.5.5 Review of methods of underpinning

Pile underpinning is not always suitable because it generally requires the incorporation of the

current footings, of which there may be none in historic buildings. Another reason why pile

(and indeed, pile-and-beam) underpinning is not always desirable is that the installation of

piles might be damaging to sensitive structures. It is for this reason that mass concrete and

pier-and-beam underpinning methods are the favoured methods of underpinning historic

buildings. Of these two, mass concrete underpinning is generally preferred for simplicity and

economy.

4.6. Conclusions

It was found that mass concrete underpinning is the most useful technique in securing the

foundations in any historic building, thus preventing any further damaging movement of the

building. Mass concrete underpinning is preferred over other methods for reasons of economy

and protection of the building being repaired. It forms an integral part of the whole process of

building conservation, as building movement is a major cause of many problems which

necessitate repairs on historic buildings. Indeed, it is imperative that underpinning is carried

out before any other structural or superficial restoration work is undertaken.

4.7 Recommendations

Reviewing literature on the subject of foundation repair in historic buildings revealed that

there is not much prescriptive guidance available to help engineers and architects formulate

solutions to any particular historic building foundation repair problems they may be faced

with. The variation in the types of buildings and their associated foundations is simply too


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great for texts to address the issue with any kind of specificity. It is proposed that the best

option for an engineer seeking guidance with a foundation repair on a historic building is to

look at past examples of similar cases, both successes and failures, and then try to avoid

previous mistakes and develop and advance proven techniques.

It is therefore recommended that a specific journal be established to which engineers and

contractors could submit reports on restoration works they have been involved in, divided into

different general building types (e.g. churches/cathedrals, castles, towers etc.). In this way, an

engineer could refer to this journal to find similar examples to the type of problem they are

faced with and consequently have a solid knowledge base on which to begin their formation

of a solution. Since there is already legislation in place regarding actions involving historic

buildings (see Section 1.3), it might be desirable to make the submission of such a detailed

report regarding any works on historic buildings a legal requirement, although assessing the

feasibility of this kind of auxiliary legislation is outside the scope of this report.

4.8 References

Beckmann, P. & Bowles, R., (2004). Structural aspects of building conservation. Oxford:

Butterworth-Heinemann

Building Research Establishment, (1993). Underpinning. BRE Digest 352. London:

Construction Research Communications Ltd.

British Standards Institution, (1998). BS 7913:1998 Guide to the principles of the

conservation of historic buildings. London: BSI

Chapman, T., (2007). Reuse of foundations. London: CIRIA


Press

Hodgkinson, A., (1986). Foundation Design. London: Architectural Press Ltd.Maintain our Heritage, (2004). Putting it off: How lack of maintenance fails our heritage.

[internet]. Bath, England: Maintain our Heritage.

Available at: http://www.maintainourheritage.co.uk/pdf/report.pdf [accessed 9 April 2008]

Sass-Klaassen, U., Vernimmen, T., Baittinger, C., (2008). Dendrochronological dating

and provenancing of timber used as foundation piles under historic buildings in The

Netherlands. International Biodeterioration & Biodegradation 61 (2008), p.96-105
http://www.maintainourheritage.co.uk/pdf/report.pdfhttp://www.maintainourheritage.co.uk/pdf/report.pdf


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5. Restoration of old stone, brick and mortar walls

D. Morrissey5

5


Abstract. The aim of this chapter is to provide a comprehensive insight into the

restoration of old stone, brick and mortar walls. Historic buildings cannot be

viewed as stationary impermeable and maintenance-free structures, when these

buildings were built they were designed to interact with their surroundingenvironment, they move and breathe like living organisms. Stone was the main

building material used in Ireland from neolithic times right up to the beginning of

the twentieth century, it has withstood the test of time and it is a material that

most people view as maintenance-free, however this is untrue, stone is vulnerable

to weathering especially in modern cities with high levels of pollutants. In order

to protect our great stone buildings responsible restoration and conservation must

be practiced. Careful attention must be paid to the materials and methods we use

in looking after these historic structures. Brick and mortar wall construction

became widespread in Ireland in the 19th century, these structures were robust,

cost effective and attractive. Brick and Mortar walls were also designed to

breathe and move according to weather conditions, they are also vulnerable to

weathering especially in urban areas due to the effects of pollution. All these

factors must be borne in mind when restoring brick and mortar walls and we must

use methods and materials which are sympathetic to their original construction.


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5.1 Introduction

Stone was used as a building material in this country as far back as 5000 years ago. The

Neolithic age took place around 2000 3000 BC, this is commonly referred to as the Stone

Age. Right across Ireland one can find primitive structures dating from this period, the most

impressive of these by far is the burial tomb at Newgrange, Co. Meath. This structure covers

an acre and a half and demonstrates the engineering ability of the people of the time. It is a

testament to stone as a building material that this structure has stood for almost 5000 years

and is still structurally sound. Stone was used in construction across Ireland because of its

abundance and durability. Limestone is the most predominant rock type in Ireland, it is both

attractive and durable. Sandstone, granite and slate were also popular in wall construction in

times past. Today stone is seen as an expensive building material and is used sparingly.

Since the advent of concrete and steel framed buildings at the beginning of the twentieth

century walls have lost some of their functionality, they are no longer structural load bearing

objects and now serve a purely aesthetic purpose in many modern buildings. It is for this

reason that we no longer use stone as the main material in wall construction, it has been

replaced by concrete panels, glass and timber cladding. The stone wall is now a rarity and it

is for this reason that we must practice responsible conservation and restoration of our historic

buildings.

The second part of this paper covers the topic of restoration of brick and mortar walls. Bricks

became a popular material in wall construction in the mid 18th century. It proved to be easier

to work with than stone and also allowed for quicker construction. Bricks were manufactured

in local foundries all around Ireland, the main raw material, clay, was abundant in most parts

of the country. Many of Irelands greatest historic buildings were constructed of brick, such

as the great period houses of Dublin city centre. It is not as durable or attractive as stone but

is still an important part of our building heritage. Like stone it is important that we aresympathetic in our methods and conservation of brick and mortar walls.


Earl (2003) provided a general overview of the principles of conservation which should be

observed when restoring a historic structure. ICC (200?) discussed at length the methods and

materials which should be used when restoring historical structures. Baer et al. (1998)

provided an insight into the methods and materials used to conserve and restore brickstructures. Baer and Snethlage (1996) dealt particularly with restoring stone built structures


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and the methods and materials used in their restoration. Forsyth (2007) discussed the various

construction methods used in historic structures and techniques of conservation. Pava and

Bolton (2007) was the most relevant to my project as it encompassed the various types of

historic buildings that exist in Ireland in particular, the materials and methods used in their

construction, and the relevant methods of conservation. The Irish Georgian Society website

(http://www.igs.ie) provided guidance on relevant literature and the relevant topics of research

to include in this project.

5.3 Causes of decay in old walls

Stone, brick and mortar contain a variety of minerals which are in equilibrium. When the

stability of this mineral balance is disturbed by external factors, the mineral balance readjusts

to become stable with the new external conditions, this process is known as decay or

weathering. In rural areas the surrounding climate is primarily responsible for weathering and

decay however in urban areas high levels of pollutants and chemical compounds in the

atmosphere rapidly increase the rate of decay of stone, brick and mortar.

The main factors which influence the decay of building materials can be classed into three

main groups:

The characteristics of construction;

The type of stone/ brick used in construction;

The surrounding environment.

5.3.1 Characteristics of construction

A buildings orientation, foundations and geometry can all affect the rate at which it weathers.

Building faades which are south facing typically recieve more sunlight and therefore provide

the ideal growth medium for micro-organisms which feed of minerals in the outer layer of the

building material. Solid foundations are not always present in historic buildings, if a structure

is built on unstable ground it is prone to movement which in turn leads to rupture and

cracking of the structures walls. The geometry of building can also affect the rate at which it

weathers, sheltered areas can be susceptible to soiling due to moisture and pollutant retention


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whereas exposed faades experience physical weathering which can wash away any decay

agents before they attack the stone.

5.3.2 Type of stone/brick used in construction

Certain types of stone and brick prove to be much more durable than other types. Stone with

a high quartz content tends to be more resistant to chemical attack than stone with a high

calcite content which is dissolved by acidic solutions such as rainwater. The same principles

apply to brick- those which were made with clays with high calcium concentrations tend to

react with rainwater more readily than those with a high silica content. Other factors which

influence the durability of brick include the way in which it was fired and if there was a

glazing treatment applied to the bricks before it was fired.

5.3.3 Environmental Factors

The location of the building, its surroundings and the general atmospheric conditions in the

area have an influence on decay agents such as water, atmospheric pollution and ice, thermal

changes, wind and salt minerals, and therefore have a huge bearing on the type and rate of

decay. Stone and brick decay vary between urban and rural areas due to varying levels of

atmospheric pollution. The main atmospheric factors affecting decay are climate and

pollution. Climate can influence the type of weathering; freeze-thaw action; rainfall; sunshine

all influence the type and rate of decay.

5.4 Materials and methods used in the repair of old walls

There are several stages to take into account when repairing a damaged stone or brick andmortar wall, they are as follows;

Diagnosis study of causes and mechanisms of decay and the history of the wall in

need of restoration. It involves mapping of decay forms found on the wall in question

and studying the composition and condition of the stone or brick in question.

Cleaning the removal of dirt and deposits from the wall

Pre-consolidation the superficial hardening of the building material prior to

cleaning, it is only carried out in cases of advanced decay.


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Consolidation the reinforcement of stone or brick which has lost its cohesion using

bonding agents

Protection shielding the stone or brick by applying water repellents which act as a

barrier to pollutants and water.

Reconstitution includes the replacement and recycling of badly damaged stone or

brick and the replacement of badly damaged mortar.

Maintenance the periodic inspection of buildings to control their evolution and

assess their condition. It is important to prevent decay by detecting and repairing

minor failures. Maintenance of historic buildings is essential practice in order to

conserve them long into the future.

Good conservation practice should delay or halt the decay of the building or object. It should

also improve the condition of the material and where possible its external conditions and

surroundings. To halt the causes of decay can often be very difficult for example, it is

difficult to control pollution arising from traffic in built up urban areas. A conservation

strategy should be carefully planned, and based on the study of the building material, the

causes of decay and its needs. It is expensive to clean, consolidate or re-point buildings with

unsuitable products which may cause further damage in the near future.

5.5 References

Earl, J., (2003). Building conservation philosophy. 3rd ed. Shaftesbury : Donhead

ICC: International Centre for the Study of the Preservation and Restoration of Cultural

Property. (200?). Conservation of architectural heritage, historical structures and materials.

Baer, N.S., Fitz S. & Livingston R.A., (1998). Conservation of historic brick structures:

Case studies and reports of research. Shaftesbury: Donhead

Baer, N.S. & Snethlage, R. (1996). Dahlem Workshop on Saving our Architectural Heritage:

The Conservation of Historic Stone Structures (1996 : Berlin, Germany) Saving our

architectural heritage : the conservatio

104612422 Conserving Historic Buildings

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