Development Services

Householder Design Guide

2

Index Page

Introduction 2

Amenity 3 Harmony 3

Materials and Details 4

Windows 5

Fitting in the Street 5

Extensions 6

Roof Extensions 7

Rooflights 9

Detached Outbuildings and Garages 9 Do I need consent? 11 Building Regulations 11 Special Rules in Conservation Areas 11 Enforcement 12 Listed Buildings 12 Other legislation 12

2

Householder Design Guide Introduction This guide has been put together to help you design householder extensions to properties in Wiltshire. It goes through all the aspects that the Council will look at in deciding planning applications for alterations to peoples homes. All planning applications are determined in accordance with the policies in the Adopted Local Plans (which are available for viewing on the Councils website www.wiltshire.gov.uk). The guidance in this leaflet will help you meet the criteria within these policies and overcome other considerations which are taken into account when deciding planning applications. This guide indicates the design expectations of Wiltshire Council and is to be used as guidance for householder applications. Before you start..... Planning and Building Regulations explained Planning seeks to guide the way our towns, cities and countryside develop. This includes the use of land and buildings, the appearance of buildings, landscape considerations, highway access and the impact that the development will have on the general environment. Building Regulations set standards for the design and construction of buildings to ensure the safety and health for people in or about those buildings. They also include requirements to ensure that fuel and power is conserved and facilities are provided for people, including those with disabilities, to access and move around inside buildings. Principles of Good Design In general, extensions should normally reflect/respect the design of the original building, and have regard to the character of the area and the amenities enjoyed by your neighbours. This means making sure your extension does not significantly disrupt your neighbours’ enjoyment of their own home, garden or neighbourhood. Not all houses are able be extended to the extent wished. In some cases there will be limited space, or their position or design will mean any extension may unduly harm the street scene or local amenity. In addition, there is usually a natural limit to the amount of extension most houses can accommodate. This means that sometimes, extensions which may individually meet these guidelines may still be considered unacceptable, due to the cumulative impact.

3

1. Amenity Extensions should not be unduly overbearing or unduly obtrusive and care should be taken to ensure that they have a limited impact regards the following: • Loss of privacy by overlooking adjoining properties. Loss of light or overshadowing of adjoining properties, particularly loss of light to main windows serving principal rooms such as living or dining rooms. • Loss of outlook from adjoining properties. • Loss of sufficient parking space • Loss of garden, landscaping or open space which contributes to local amenity • Overbearing/sense of enclosure to adjoining properties An extension at the rear of your property may affect your own amenities by reducing your garden size or restricting natural light to your own existing rooms, forcing the use of expensive artificial light for much of the day. Outlook An extension’s projection can seriously affect the outlook or light provision to an adjoining owner nearest habitable room. Two storey rear extensions to semi-detached and terraced dwellings are usually very prominent in views from adjoining dwellings and will dominate outward views from adjoining ground floor windows, appearing excessively large and dominant.

2. Harmony Proposed extensions should normally respect and reflect the form, scale and architectural style with the original building and area. This can be achieved by:

Respecting the proportions of the existing house.

Using an appropriate roof form.

Match/reflect materials and details.

Match/reflect window style and position

Reflect the character of the original house

Whichever type of design is proposed:

The extension should usually be subordinate/subservient to the original house.

The extension should ideally be in proportion both in its own right and in relation to the original building.

The height of the extension should normally be lower than the height of the original building.

For example, this can often be achieved by stepping down the roofline and setting back the front building line of the extension.

4

3. Materials and Details External finishes, materials and architectural features will affect how your extension looks. Normally, the brick colour/type and the mortar joints should match those of the existing house. Similarly, the design, proportions and position of joinery details, windows and doors should respect those of the original building. Ideally, any vertical or horizontal emphasis or hierarchy of windows should be followed- traditionally, windows should get smaller the higher up the house they are. Where a flat roof is appropriate on a single storey extension the roof should relate to original horizontal elements such as canopies, string courses, or to the line of change between materials e.g. brick to render or tile hanging. Brick on edge coping is usually more satisfactory than a timber fascia board. The roofline of the extension should generally follow through or be lower than the original. Diagram showing windows and detailing in the extension matching the main dwelling

Diagram showing unnecessary detailing

5

4. Windows

The design, position a n d size of windows a n d doors on the extension must reflect t he

design, position a n d size of the ones used in the main house. To avoid overlooking of

neighboring properties, windows and doors should only be placed in the front and rear walls

of the extension. If windows are proposed in the side wall, they should be at a high level,

non-opening and of obscure glazing. An alternative means of providing daylight to an

extension is via the insertion of roof lights

5. Fitting in the street Your extension should fit into the general street scene as a whole. Follow these pointers to improve the acceptability of the works:

Take account of the group value, character and established form of development along your street;

Use designs and materials which compliment the character and design of existing and neighbouring houses;

Take account of changes in levels between properties and gardens;

Leave enough space between houses to ensure they appear visually separate;

Protect important glimpsed views between buildings which allow greenery to be seen from the road;

Take account of existing features along the boundary, for example, outbuildings, fences, walls and trees;

Roofs should be finished in a manner that complements the roof form of the original house and the surrounding area; and

Take account of the angle and position of your house. This may increase the impact of your extension on the street scene.

6

6. Extensions The proposed extensions and alterations should not dominate the existing building: in other words they should be subservient, and appear as additions in a ‘supporting’ role. The existing building should not be dominated by the bulk or volume of the extension, otherwise the character of the existing building could be lost. This consideration will be paramount if the building is Listed or is in a Conservation Area. The approach should be that the extension is designed as an addition, rather than a duplicate or an enlargement. Front Extension It is important to ensure that front extensions do not detract from the continuity of the street scene. Extensions are not generally acceptable where there is a clear and visually obvious ‘building line’ which would be disrupted. Conversely, where the building line is staggered or indistinct, a front extension could be acceptable.

Side Extension Extending exactly in line with the existing building can draw attention to the differences between new and weathered bricks/stonework, tiles and mortar joints. It also often makes the existing building look lopsided. In historic buildings it may be important to distinguish between the historic building and a later addition. It is therefore important to set back the extension at the roof ridge and where the new walls meet the existing. The wall set back should be at least 112mm (4.5 inches) - a brick dimension, but often a more significant set-back will be beneficial. It is recommended that garages should be set back by at least one metre. There are many ways in which the visual impact of an extension can be reduced. A drop in the ridge or eaves line for example. Pitched roofs can help highly visible extensions fit in with the street. Side windows or other detailing can also help improve the appearance of a flank wall. The detailing of the extension should generally reflect or be complementary to the original dwelling and/or the surrounding area. For example, in the size and design of windows, the pitch and style of the roof, the detailing of headers and cills, treatment of eaves and verges; the pattern or bond of brickwork, the coursing of stonework; or details of quoins. All these details can have a significant effect upon the success or otherwise of the extension and its impact on the appearance of the original house and the streetscene. In order to reduce the impact of two storey or first floor side extensions, there should usually be a gap of at least 2m between the flank walls of properties at first floor level and a minimum gap of 1m between the boundary and the extension at first floor level. A larger gap may be required if the adjoining property would in any way be demonstrably harmed or where the gap between properties forms an important part of the character of the area.

Where possible an existing direct access to a rear garden should be retained. Rear Extension Single storey extensions to the rear of a house projecting up to 3 metres in depth along the boundary with an adjoining property will normally be acceptable. However even 3 metre rear extensions in these locations are sometimes too deep where:

7

Houses are already ‘stepped’ and sit forward of their neighbours

There are significant changes in levels; or

They would look too bulky and prominent compared to the size of houses and gardens to which they relate

Where an extension is set off the boundary then a deeper extension may be acceptable. Two storey rear extensions are often problematic in terraced properties or where detached or semi-detached dwellings are close together because of:

loss of light and outlook because windows and doors are so close to the extension.

unacceptable sense of enclosure to house and garden.

Appearing overbearing In some cases single storey rear extensions on neighbouring properties may reduce this effect but the extension may still be out of character with the existing form of the surrounding properties or the bulk of extension may look inappropriate from surrounding gardens. On detached or widely spaced semidetached houses there may be more room for rear extensions. Windows should be carefully located to avoid any overlooking (or the perception by neighbours that they are overlooked). Use of obscure glazing, high level windows and fixed casements can over-come concerns regarding privacy. However, this approach is only generally acceptable to bathrooms, hallways or non-habitable spaces. A bedroom where the only window would have to be obscurely glazed and fixed shut to avoid overlooking would not generally be acceptable and should be avoided. Flat roofs should generally not be used as balconies where there are nearby residential properties as loss of privacy almost always results. This applies to side as well as rear extensions. Raised patios can also have a marked effect on neighbours. In some cases they need planning permission and care should be taken that they do not result in loss of privacy or outlook for Neighbours. Granny Annexe: If the purpose of the extension is to provide accommodation for a relative, it must not have a separate entrance or staircase. The extension should be internally connected to the rest of the house and should share facilities such as a kitchen.

7. Roof extensions Further usable space may be created by converting the roof space, often involving the formation of dormer windows or rooflights. However, you should not automatically assume you will be able to extend into your roof – many houses have roofs which are too small for conversion or, in some cases, dormer windows may be out of keeping with the area. In almost all cases, roof extensions in listed buildings which require any alterations to the historic fabric, the introduction of dormer windows or rooflights are unlikely to be acceptable.

8

Dormer Windows A dormer window is a vertical window or opening in a sloping roof, having its own roof, either flat, pitched or curved. Since it can have a significant effect on the appearance of a house, its design needs careful consideration in line with the following principles Design – The design of a dormer window should:

reflect the style, proportion and shape of the existing house and roof design

be designed to provide light to existing spaces and not as an opportunity to create an enlarged floor area

always be located at the rear of the property unless dormer windows are a particular feature of the surrounding streetscape

work on the principle that small is beautiful – two smaller dormer windows will always be preferable to one larger structure

minimise overlooking of adjoining properties; where this is not possible, rooflights may have to be considered as an alternative

Position – Dormer windows should

line up with the existing windows below

be set well back from the front or rear wall of the property and below the existing ridge line

neither wrap around existing roof slopes, nor match nor exceed the ridge line

on semi-detached or terraced properties, be set in approximately 1m from the party wall, flank wall or chimney

Proportion and scale – To retain a proper balance

the window and the dormer frame to each side of the window, including cheeks, should be smaller than the window below it

the entire dormer structure should be subordinate in the roof and should not occupy more that one third of the width or half the depth of the roof slope.

dormer cheeks should be the minimum necessary to simply frame and support the window opening

the pitch of the roof to the dormer should match that of the principal roof

the window itself should reflect the style and design of those below.

Materials

the materials used should match the existing roof as closely as possible

dormer cheeks should be finished with lead, tiles or slates or other traditional material

the top of a flat roofed dormer should be finished with lead in preference to roofing felt

9

Whole Roof Extensions In exceptional circumstances, it may be possible to extend the whole of the roof from a hip to a gable. However, this will only be appropriate where

the gable would not unbalance a pair of semi-detached houses or a short terrace

the gable would not reduce the degree of visual separation between houses or glimpsed views from the street

the gable would not form an overbearing wall facing a street, neighbouring garden or window, or other public place

the gable would not be out of character with the streetscape

any new windows in the gable end would not result in a loss of privacy

8. Rooflights

Rooflights can be a cheaper and simpler means of allowing light into the roofspace where a traditional dormer cannot be used, and are generally less intrusive. However, they should adopt the following principles

they should be fitted flush with the plane of the roof and not stand proud of the roof profile

where possible, they should be located in the rear, or more hidden roof slopes

windows with a vertical emphasis are generally more appropriate and provide a greater amount of light than square or horizontal styled lights

rooflights sited at 1500mm above floor level will ensure no overlooking of neighbouring properties or gardens but will not be suitable for emergency escape purposes

when more than one rooflight is fitted in a single roof slope, they should be of similar size and shape and installed at the same height

in barn conversions and sensitive rural locations, rooflights are generally regarded as unacceptable, irrespective of their size and position

in Conservation Areas, 'conservation' style rooflights will be expected in any elevation which can be seen from public views

9. Detached Outbuildings and Garages

Detached buildings and structures can have as significant an impact on local character and amenity as extensions and they require a similarly careful approach to design. The following principles should be adopted Outbuildings

detached buildings are not normally acceptable at the front of semi-detached or terraced houses because of their dominant impact on the street scene and adjoining properties

on detached properties, they are only acceptable in front gardens where detached buildings form part of the existing character of the street e.g. where garages were built as part of the original layout of an estate

10

the size and design of the building should relate to its purpose and be no larger than is

necessary

2 storey buildings will generally not be appropriate or acceptable

buildings should be proportionate to the size of the main house and not significantly reduce the amount of usable garden space

buildings should be sited so as to have the minimum impact on neighbouring properties and gardens, both in terms of outlook and overshadowing and potential noise nuisance

the design and detail should complement the main building, together with the use of appropriate materials

The outbuilding must only be used for normal domestic uses ancillary to the residential use of the main dwelling.

Garages In addition to incorporating the points above, other specific considerations apply to the erection of detached garages:

where possible, garages should be located to the side of the main house between the front and rear elevations

a minimum distance of 6m will be required between the front of the garage and the adjoining pavement or road where there is no footway

avoid locating garages deep in rear gardens unless there is a rear access since this will require long driveways which can be unneighbourly and reduce the usable garden area

the materials used should match those of the main house

prefabricated structures are not generally considered suitable where they will be visible from public views

the scale and design of the garage should relate to the existing house, particularly in terms of its roof design eg a hipped roof garage will look out of keeping with a gable roofed property

in constructing a double garage, two single doors with a central division will generally be more appropriate than one larger double door

large flat roofed garages are generally unacceptable if visible from public views; if a pitched roof is not a feasible option, a design detail such as a parapet wall, will be expected

Planning application packs, guidance and validation checklists can be found on the Councils website www.wiltshire.gov.uk

11

Do I need consent from the Council?

1. Planning Permission Planning permission is generally required for new buildings, but some smaller house extensions may fall within a special exemption called ‘permitted development’. If they do, they will not require planning permission but they may require approval under the Building Regulations and if appropriate, Listed Building Consent. In many cases, depending on their size and siting the formation of dormers or detached buildings in gardens may constitute ‘permitted development’. In all cases check to see if consent will be required under the Building Regulations. Our team of Building Control Officers would be happy to discuss any projects with you. For a simple guide to these national regulations as to whether planning permission or building regulations approval may be required, visit the interactive house on the portal website at: www.planningportal.gov.uk If you need information on the planning history of your property please contact the Council on 0300 456 0100. Planning application packs, guidance and validation checklists can be found on the Councils website.

2. Building Regulations It is a statutory requirement to gain Building Regulations approval for most extensions to your property, internal alterations, new and replacement openings, structural changes or any alterations that affect a thermal element, ie re-roofing. It is important to take account of Building Regulation requirements at an early stage and certainly before finalising your proposal to check that your scheme will still provide you with what you want. Generally if you require help with your project you can contact a Building Control surveyor for free pre-application advice. In addition, full copies of the Building Regulations are available at www.planningportal.gov.uk

3. Special Rules in Conservation Areas A conservation area is an area identified and designated by the local authority as being of special architectural and historic interest. Within conservation areas different ‘permitted development’ rules apply, and because of their particular character, the Council will require a higher standard of design and materials than elsewhere. Some of the conservation areas are subject to what is known as ‘Article 4 Directions’. These directions require that planning permission be obtained for extensions or alterations that would otherwise constitute ‘permitted development’. When carrying out works to trees within a conservation area you are required to apply for consent.

12

4. Enforcement Take care! Failure to obtain planning permission can lead to enforcement action being taken and you may have to take down your extension It is also important to make sure you build what you actually have consent for. If you build something bigger, or with different details or windows it is likely that enforcement action will be taken against you. This may mean you having to rebuild your extension in line with your consent.

5. Listed Buildings Extensions or internal and external alterations (Including any demolition) which affect the character of a listed building will require listed building consent in addition to any planning permission which may be necessary. The fact that a proposed extension may itself be ‘permitted development’ does not negate the need to obtain listed building consent. If you are considering works to alter or extend a listed building you are strongly advised to discuss your proposals with the planning department at an early stage. Failure to obtain listed building consent is a criminal offence punishable by a fine or even imprisonment Other Legislation All applicants should also check whether: (a) Any trees affected by the proposal which are subject to a Tree Preservation Order will require consent for any works, including the cutting of roots. b) The proposed building works require permission under the Building Regulations. It is almost certain that the types of extension described here will require Building Regulations approval. c) If you intend to work on an existing wall or structure shared with another property; build a free standing wall or a wall of a building up to or astride the boundary with a neighbouring property or excavate near a neighbouring building you may have to notify neighbours under the provisions of the Party Wall etc. Act 1996. Certificate of Lawful Development If you are in any doubt as to whether planning permission is required you can apply to the Council for a Certificate of Lawful Development. The certificate confirms whether or not planning permission would be required for the proposal. The appropriate forms and an explanatory leaflet are available from the Council and should be submitted with the appropriate fee.