Nigel Gervis, Founder & Technical Director,

Ty-Mawr Lime Ltd

The Benefits of Lime

Building Regulations - Context

Guide to the Conservation of Historic Buildings

• The standard includes information such as walls can be 30% less energy efficient if damp and good repair provides greater energy efficiency. (Section 5.3.1)

• Impervious materials can be harmful including cement pointing and rendering and most types of impervious solid wall insulation and the Standard states that removal should be considered.

• Section 5.3.1 states ‘some energy efficient measures can have an adverse effect on sustainability’.

• Section 7.4 on materials emphasises that ‘the removal of historic fabric and patina should be avoided as far as possible to retain authenticity’.

• Section 0.1 highlights that British Standards that are applicable to newer buildings might be inappropriate.

British Standard 7913 British Standard 7913

Solid Wall Construction – Simple & Robust

Building Health

1.64

0.60

0.460.37 0.32 0.28

0.20

2.20

0.660.50

0.400.34

0.29

0.00

0.50

1.00

1.50

2.00

2.50

40mm 60mm 80mm 100mm 120mm 180mm

W/(

m2

K)

Insulation Thickness Wood Fibre or Expanded Cork

Limestone 600mm Slate 600mm

What effect do different thicknesses of insulation really have?

Wall Types

The Lime Cycle

Clay,

sand,

straw,

earth

Pure/

Lime Putty

Feebly

hydraulic

NHL2

Moderately

Hydraulic

NHL3.5

Eminently

Hydraulic

NHL5

Roman /

Natural

Cement

Ordinary

Portland

Cement

Other Names Cob /

clom

Fat, High

calcium,

White Chalk,

Air Lime

Slightly

hydraulic, grey

chalk, semi-

hydraulic

Pure natural

XHN 30

(France), semi

hydraulic

Pure

natural

XHN 60

(France)

Parkers

cement,

eminently

hydraulic lime

(Italy)

OPC

Set In Water None None 15 to 20 days

or more

6 to 8 days 2-4 days Initial set in

the order of

15 minutes to

2 hours

Initial set

30 minutes

Final set 6 -

10 hours

Impurities Negligible Under 12%

active clay

12-18% active

clay

18-25%

active clay

Up to 55%

active clay

N/mm2 Up to

0.77

0.3 to 0.5 1.3 to 2.0 2.0 to 5.0 5.0 to 10 10 and above 28 to 50+

Types of materials Types of Materials

Building Health

Building Health

For further information…….

www.lime.org.uk

For further information…….

…and catalogue, information leaflets, newsletters

…and catalogue, information leaflets, newsletters

For further information…….

Practicing what we preach…..

…you are very welcome visit or come on a course!.

Repair within the rules….simple and appropriate