Extension Design Guide

Introduction

Many people wish to make additions to their home. Extensions can improve living conditions by making more space available and enable occupiers to adapt accommodation as family circumstances change. Well designed extensions may also add to property value.

 

Extensions to properties provide valuable additional internal space but can, if poorly designed, spoil the appearance of the house or the street or adversely affect neighbours. The external design of alterations and extensions is often a matter of personal preference. This guide sets out general advice and the Planning Committee's particular requirements to help householders considering an extension to their home. Advice from architects or professional designers can provide new ideas and highlight potential problems leading to the quicker granting of planning permission and to reduced costs in the longer term. Advice should be sought at an early stage with regard to the requirement for planning permission or building regulations approval.

 

The Fareham Borough Local Plan at Proposal EN1 provides advice on standards of development. The guidance in this leaflet, produced as a supplement to the Local Plan, expands on this policy. Although the diversity of house styles within the Borough makes it impossible to cover every type of extension or situation the guidance will apply to the design of all home extensions whether they are in the countryside, urban area or special character areas.

 

In conservation areas particular care and attention to the scale, design and materials used will be necessary. Works internal or external, to a listed building will normally require listed building consent, as will any proposal involving even partial demolition. Works involving partial or complete demolition of unlisted buildings in Conservation Areas will generally require Conservation Area consent. Early consultation with the local planning authority is advisable in either case and guidance on your specific proposal can be given.

 

Shape, size and style

Having made the decision to extend, the next consideration is where. Depending on the type of house and the amount of land around, it may be possible to extend at the side, rear, front or in the roof. It is important to stand back from your property and consider the type of property and its surroundings. 

 

The major influence on the design of an extension is the character of the original house including the materials used, roof shape, proportions of windows and doors. If the design of your extension reflects the shape, materials and distinguishing features of your house it will be likely to enhance the property and not detract from its character.

 

An extension should not dominate the existing building in shape or size. It will look better if it is the same height as the original building or lower. Two storey side extensions can sometimes look better if they are set back one metre from the front wall of the existing house.

 

Normally two storey side extensions should be set a minimum of one metre off the boundary to avoid a cramped or terraced appearance. However, in some cases, particularly in the more spacious areas, a greater distance may be required.

 

Outlook, Privacy and Loss of Light

Large or poorly located extensions can have an unacceptable impact on the outlook from existing dwellings. A minimum distance of 12.5 metres (40 feet) is normally required between the windows of habitable rooms in an existing dwelling and a two storey wall of a new extension where the wall contains no windows. Where two storey rear extensions are proposed, 11 metres from a window at first floor level to the garden boundary and 22 metres from facing windows is considered to be the minimum privacy requirements.

In the case of first or two storey side or rear extensions the minimum distance required between a side window serving a habitable room and a proposed development will normally be 6 metres. Only in exceptional circumstances depending upon the presence of intervening screening, the size and height of the extension and the nature of the window (main or secondary), character, levels and orientation, will smaller distances to a minimum of 4 metres be acceptable.

 

To assist in maintaining adequate privacy for neighbours you may be required to construct flank windows in extensions at high level or of obscure glaze, but this will depend on the circumstances of individual cases.

 

A common objection from neighbours is that your proposal will cut out a lot of light from their windows. An extension behind a line drawn at an angle of 45 degrees from the centre line of your neighbour's nearest ground floor window is less likely to affect them. Normally single storey rear extensions up to three metres in length on the property boundary are acceptable in relation to loss of light to and change in outlook from the adjoining property. However, site characteristics such as changes in levels, orientation and proximity of windows in adjoining properties may require the extension to be moved away from the boundary. Similarly extensions larger than three metres in length can sometimes be acceptable. Two storey rear extensions are more likely to cut out neighbours light than a single storey one and should not normally be built on the boundary. An alternative may be to have a single storey extension and a well designed dormer.

 

Balconies

There are few terraced or attached properties in Fareham that can take on the addition of a balcony without causing loss of privacy and/or detracting from the original house and street scene. Proposals for balconies will be examined very carefully to ensure there is no unacceptable loss of privacy to neighbours.

 

Porches

Adding a porch or a canopy is one of the most significant changes a householder can make to the front of a house, involving as it does a change to the focal point, the entrance.

 

In terraced developments a plan rectangular box with a flat roof of the type shown below is generally unsympathetic to the individual building and will spoil the look of the whole row.

 

Additions which follow existing characteristics such as roof pitch and window form will enhance rather than detract from the original house or group of houses. Where front doors are paired it may be worthwhile joining forces with a neighbour to achieve a higher standard and reduce costs.

 

Dormers

Roof or loft extensions are a popular way of providing extra space. In some cases where sufficient headroom exists rooflights or windows in gable walls may be all that is needed.

 

Where headroom needs to be created, a dormer may be the answer but because they are so prominent they need to be well designed to integrate with the original roof.

 

As a guide:-

• Put a dormer at the back of a house where it is less conspicuous
• Keep below the original ridge of the roof
• Do not take up the whole roof slope
• Avoid where possible dormers on the hipped end of a roof
• Dormers should be set in from the gable end
• Several smaller dormers look better than one very large one
• Where possible keep to the original style of the roof and use a gabled or hipped dormer
• Normally some of the existing roof should be left beneath the window
• Materials and design of windows should match those of the existing dwelling
• Care should also be taken to ensure new dormers do not unacceptably overlook adjacent properties
• Dormers should generally be set within the existing roof slope which should remain evident above, below and to the sides of the dormer