3.3 How to Create a Harmonious Built Form May 09 Web Tcm4-5844

8/2/2019 3.3 How to Create a Harmonious Built Form May 09 Web Tcm4-5844

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3.3How to create aharmonious built form

Vale of White Horse Residential Design Guide Spring 2009 53

Urban Grain

Once a site layout has been planned anddesigned, and the connections between a siteand the surrounding area have been established,the next step in the development process is tocreate an appropriate pattern of streets, blocks,plots, buildings and open spaces.

Create or contribute to perimeter blockforms

The grid approach, described in Section 3.2above, allows for development to be planned inperimeter blocks. The perimeter block structureis an accepted format for achieving successfuldevelopment. In particular it:

Ensures the efcient use of land.

Optimises connections to surroundingareas.Provides a clear distinction between publicand private spaces.Allows enhanced permeability andlegibility.Increases natural surveillance of the street.

When designing the layout of development usingperimeter blocks, it is important to ensure theblocks vary in size and shape. The blocks should

take into account natural features, orientationand topography, as well as the building typesthat are to be accommodated.

In general, blocks between 70 - 125 metresin length provide a better network for bothpedestrians and vehicles. Given the size andcharacter of the settlements in the Vale, largerblocks are unlikely to be appropriate.

Layout: urban grain -The pattern of the arrangement of street blocks, plots

and their buildings in a settlement.

Perimeter blocks can allow the designer the greatest freedom of

choice to accommodate a range of building types and densities. A

range of building types including two storey terraces, mews streets,

apartment blocks and semi detached houses can all be accommodated

within a perimeter block structure.

Perimeter blocks create a dened front and back which allows

private space to be clearly marked. There is no public access tothe rear of properties and the frontage can be dened by hedges,

railings and gateways appropriate to design of the development and

the character of the area.

Terraces withmews streetsbetween

Detached houses

Terraces, with apartmentblocks on corners and

courtyard parking

Apartment blockswith internal

parking courtyard

253 Perimeter block

254 Perimeter block

255 Buildings wrap around a block layout


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Typical modern semi-detached houses with parking on the front of

the plot - six houses

Victorian terraces with on street parking allow for a greater oorspace

with accommodation over three oors - ten houses

Modern townhouses and/ or apartments - with designated parking

arranged in a home zone - ten houses and twelve apartments

Rural courtyard development with continuous built frontage and a

mix of on plot, street and rear parking - ten houses

Density Comparisons - the different development types belowhighlight how alternative layouts which utilise the same size plotcan achieve a range of six to twenty dwellings by altering the densityof the development.

Density

Historically, some of the most successfulsettlements include high density development,such as medieval village and town centres, andGeorgian, Victorian and Edwardian terraces.

There are different measures of density andthe most common is the number of dwellingsper hectare (DPH). The problem with the DPHapproach, however, is that it does not highlighthow much space a building will take up on a

plot.

An alternative approach is to calculate the plotratio, which is the ratio between the size of theplot and the amount of space that buildings takeup on it. This approach can be helpful whenassessing the impact of a new developmenton the character of the surrounding area. Forexample, if the surrounding area is characterisedby buildings set in large landscaped grounds(i.e. a low plot ratio), a single large buildingwhich occupies the majority of the plot (i.e. ahigh plot ratio) would be likely to look out ofcharacter irrespective of the number of dwellingsit provides.

Make efcient use of land

Using land efciently is a key considerationin planning. Government advice is that newdevelopments should achieve a density of at least30 dwellings per hectare. In some locations,a lower density will be more appropriate, such

as rural locations and historic areas. In someurban areas, however, a higher density will bemore appropriate in the interest of creating asustainable pattern of development.

Density must be appropriate to the contextof the site

The density of new developments should beinformed by their context and by the Councilsadopted policies. The table below sets out the

range of densities in different locations.

256 Density comparisons


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Location/Settlement

Type

IndicativeDensity

Indicative Style ofDevelopment

Rural -replacement/conversion

Like for likereplacement

or lowdensity as

appropriate

Single conversions orreplacements. In exceptionalcases, it may be appropriateto replace with a smallgroup of dwellings - eachassessed individually

Small Village- Inll

30-40dph Development should reectvillage density and notsuburban character.

Village -DevelopmentPlanAllocation

30-50dph Generally low densityperiphery (30dph) with highdensity core & focal areas.Development should reectvillage density and notsuburban character.

Urban/ RuralBuffer

30-40dph There may be exceptionalcontexts where 20dph isappropriate - or gradeddensity through the site.

Outer areasof Medium/Large Village

30-40dph Higher density used nearpublic transport routes &local facilities

Centre ofMedium/Large Village

40-55dph Use upper gure of rangeon sites within walkingdistance of public transportand facilities.

Outer areasof LargerSettlements

30-50dph Use small areas of upperend of range to createkey groups or near localfacilities.

Centreof LargerSettlements

Over 50 dph Use upper gure of rangeon sites within walkingdistance of public transportand include new mixed useswhere possible.

257 Density range in settlements in the Vale

258 Single dwelling village inll

259 High density village inll

260 High density urban housing

261 High density urban apartment development


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Building Line and Frontages

The siting of buildings in relation to the streetcan have a signicant effect on the success of adevelopment. The most successful layouts havepublic fronts and private backs. These streetshave clearly dened edges and allow for naturalsurveillance.

New development should provide continuity in thestreetscene. The provision of a continuous builtfrontage maintains the public front of a street andcreates a positive rhythm in the street scene.

On-street parking must be carefully located andinclude appropriate landscaping to soften itsimpact on the street frontage.

The relationship of buildings to the street mustrespect the hierarchy of streets and public spaceswithin the development.

Identify building lines that relate to thecharacter of the area and the proposed

development

The distance that buildings are set back from thestreet help to dene the character of the street.The existing building line should inform thedesign and layout of a new development.

Dene building lines that separate publicand private space

The distance that the building line is set backfrom the street also denes the level of privacyenjoyed by a dwelling. It may, therefore, beappropriate to introduce a setback which offersa buffer between public and private realms. Eventhe smallest setback can help privacy and securityas well as provide practical storage areas forcycles or refuse.

Where dwellings are accessed directly off thestreet, front entrance areas need to be clearlyidentied. Doorways can be recessed to helpprovide a more private entrance. Buildings can abut the street

frontage, where rear courtyardsallow for servicing.

Building line maintained, but

varied by following a hierarchyof streets and spaces

Streets should not mix

fronts and back - this

creates a negative public

realm

262 Streets should not mix fronts and backs

263 Buildings with small setback provide defensible space

264 Building lines

x

x


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Vale of White Horse Residential Design Guide Spring 2009 57Vale of White Horse Residential Design Guide Spring 2009 57

Scale, Form and Massing

The scale, form and massing of new buildingshave a vital impact on the quality of thestreetscape.

Scale is a measure of the relative size of a building i.e. its height, width and depth. People usuallyevaluate the scale of a building using the size ofindividual components such as windows, doors orbrick or stone courses.

Form and massing are the overall shape and bulkof buildings.

Scale, form and massing need to beappropriate to the sites context

The scale of existing buildings in Abingdon andWantage town centres is typically three storeyswith frontages up to four bays wide. This scalereduces to two-storeys and two bays wide in lesscentral locations, and narrow single bay widths inmany of the Victorian and Edwardian terraces.

In the villages and rural areas, buildings aretypically two-storeys with wide frontages.

Add visual interest to the street scene

In some circumstances, noticeably taller buildingscan be acceptable to provide visual interest, alandmark in the street scene, or to help break upthe mass of the development. Subtle variationsin height can also be used to add visual interest.

This can be achieved with differing ridge andeaves heights, as commonly found in traditionalstreets.

Similarly, variations in frontage widths and planforms can add further interest to the streetscene.. This can be appropriate in both urbanand rural locations.

Use simple building forms

The majority of traditional buildings in the Vale,in both urban and rural areas, adopt a very simple

Urban Houses: narrowfrontage with deep aspect.Dual aspect with overlookingpublic realm to front andprivate space to back.

Rural Houses: wide frontagewith shallow aspect. Dualaspect with overlooking publicrealm to front and privatespace to back

Urban Apartments: mix of square and rectangular linked forms.Allows for visibility on all aspects including internal courtyard

communal space.

Urban Apartments: square linked forms. Allows for dual aspectvisibility to public realm or to rear communal space.

All areas Apartments/Houses:wide frontage with shallowaspect. Single aspect withoverlooking public realm - linksawkward areas where no rearprivate space can be provided.Amenity space required to sidefor houses.

All areas House: square formallows linking of all forms. Dualaspect with overlooking publicrealm to front and private spaceto back.

265 Building forms found throughout the Vale


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form, with rectangular oorplans and gablepitched roofs. Image 267 (right) illustrates how

a simple building form with wide frontages andshallow depths can produce different buildingdesigns by varying eaves and ridge heights.

Where buildings are of more complex shape, theyshould be composed of a hierarchy of simpleelements each with its own pitched roof.

Where ats are the main dwelling type, the scaleof the buildings can be noticeably larger thanexisting buildings in the area. A design solution

is to divide the building into visually distinctelements in order to reduce the overall scale e.g. wings and bays and varying eaves and ridgeheights.

Use scale to aid legibility

The scale of buildings can also be used toimprove the legibility of a street. For example, intowns and villages the important buildings suchas churches were traditionally taller and therefore

more visually prominent. In new developments,individual landmark buildings should be taller toaid legibility.

One and a half storey:rooms in roof to be lit by smalldormers. low ceilings as foundin traditional cottage

Two storey: upper oorpartially in roof space and lowceilings as found in traditionalcottage

Full two storey: high ceilingsas typical of urban Victorianhouses.

Two and a half storey: highceilings and restricted third oorheight in roofspace as typical ofurban Georgian houses.

By grouping the above four different scale dwellings together, signicant variety isadded to the streetscene. This is particularly effective, given that all units conformto the same plan form.

266 Form and Height - how scale adds interest and variety

2

1

2

1

2

3

1

2

1


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Enclosure

Enclosure is determined by the height of thebuilding frontage relative to the width of thestreet or square. Trees, hedges and walls canalso contribute towards creating a sense ofenclosure.

Types of enclosure can include large and smallscale, formal and informal, building dominatedor landscape dominated. Spaces can be staticsuch as a square or courtyard, or dynamicsuch as a street where movement is the maincharacteristic.

Avoid conned spaces, which can feeloppressive

Avoid open spaces that lack character orpurpose

A simple way of evaluating enclosure is tocalculate the ratio of the height of the buildingsto the width of the street or space. As a rough

guideline, a ratio of 1:2.5 to 1:3.5 is likely to beappropriate. The overriding factor is that thespace between buildings is a safe and pleasantplace and does not feel oppressive.

Landscaping can help to create a sense ofenclosure e.g. specimen trees framing thestreet.

Provide a sense of enclosure appropriate topeople

A signicant challenge for larger residentialdevelopments is to provide a scale that isappropriate to people rather than cars. Whenbuildings are set close to the street it is importantto ensure they relate to the human scale. Whenbuildings are set back from the street, it isimportant to ensure that roads and parking areasdo not dominate the street scene.

267 Victorian/Georgian town centre enclosure, Abingdon

268 Village enclosure formed by walled front gardens, Wytham

269 Estate village enclosure - deep front gardens and trees, Lockinge


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Avenue1. : Avenues can lack enclosure if poorly dened. Successful enclosure can be achieved by introducing taller building, withformal tree planting between the buildings and the road.

Public open space2. : Appropriate enclosure can be achieved by wrapping apartments or townhouses around the open space. Thishas the additional benet of providing natural surveillance of the open space, thereby improving security.

Residential street3. : A high degree of enclosure is provided on residential streets which are typically aligned with 2-3 storeydwellings. Interest can be added to the streetscene by varying roof and eave heights.

Internal courtyard4. : Single to 1.5 storey, potential for occasional 2 storey where residential accommodation above garageblocks.

Square5. : Focal features and building height terminating the vista from each direction. Enclosure is created by formal tree plantingwithin square

2.

1.

3.

3.

4.

5.

270 Scale and enclosure - variety of approaches


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Corner Buildings

Corner buildings offer an opportunity to givedistinctive character to a place and shouldtherefore be specically designed for the cornersite. Standard house types are not appropriateon corner sites.

Linking houses together at a corner can causeproblems with garden space and privacy. Image272 below illustrates this problem, and offers asolution to the problem.

By extending plot 3 to turn the corner and setting back plot2 it provides sufcient space for a garden. By providing plot2 with a single storey element and an adjoining brick wall, it

further assists with maintaining a built frontage.

2

2

3

3

4

4

X

Enclose the spacewith a wall

Linking houses together at a corner causesproblems with garden space and privacy.Here the example shows there is no garden forhouses 2, 3 and 4.

Maintaindaylightingand privacy

Allow rearaccess

271 Unsuccessful corner buildings and gardens

272 Successful corner buildings and gardens

273 Wide aspect Georgian townhouse turns corner successfully

274 Modern townhouse turns corner successfully

275 Village cottage turns corner allowing rear garden

3.3 How to Create a Harmonious Built Form May 09 Web Tcm4-5844

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