Extensions and loft conversions


With a long history of building extensions to a vast array of property types, BSS’ expertise in this field is widely known.
Successful project management ensures that a family can continue to use their home throughout the works and an understanding of what can and cannot be done, both legally and physically, means that the home owner gets a surprise-free construction and a beautiful, home-changing addition to their property. Our design team will help you understand how a space becomes most beneficial, the importance of light and of course the most cost effective and productive means of tailoring this knowledge to suit your home.
The legislation around home extensions varies depending on property type and area but in general, the following applies;

Extensions: What you can do without planning permission
• You can extend a dwelling by 4m to the rear if it’s single storey or 3m if it’s double.
• There are height restrictions but they boil down to a single storey extension not being higher than 4m in height to the ridge and the eaves, and ridge heights of any extension not being higher than the existing property.
• Two storey extensions must not be closer than 7m to the rear boundary.
• It must be built in the same or similar material to the existing dwelling.
• Extensions must not go forward of the building line of the original dwelling.
• In Designated Areas side extensions require planning permission and all rear extensions must be single storey.
• An extension must not result in more than half the garden being covered.
• You can only do it once and the original building is either as it was on 1st July 1948 or when it was built


Loft Conversions
A loft conversion for your property is considered to be permitted development, not necessarily requiring an application for planning permission, subject to the limits and conditions below:
• The volume allowance of 40 cubic metres additional roof space for terraced houses
• The volume allowance of 50 cubic metres additional roof space for detached and semi-detached houses
• No extension beyond the plane of the existing roof slope of the principal elevation that fronts the highway
• No extension to be higher than the highest part of the roof
• Materials to be similar in appearance to the existing house
• No verandas, balconies or raised platforms
• Side-facing windows to be obscure-glazed; any opening to be 1.7m above the floor
• Roof extensions not to be permitted development in designated areas**
• Roof extensions, apart from hip to gable ones, to be set back, as far as practicable, at least 20cm from the original eaves
• The roof enlargement cannot overhang the outer face of the wall of the original house.


Outbuildings: What you can do
• You can construct all sorts of outbuildings for the use and enjoyment of the home so long as they do not cover more than 50% of the garden space. In Scotland this is reduced to 30%.
• In Wales and Northern Ireland any outbuildings closer to the house than 5m count as extensions. In Scotland any outbuildings larger than 4m2 and closer to the dwelling than 5m count as extensions.
• Outbuildings must be single storey with a maximum ridge height of 4m for a pitched roof or 3m for any other kind of roof. The eaves height must be no more than 2.5 metres.
• If the outbuilding is closer to the boundary than 2m it shall be no higher than 2.5m.

Did you know…?
Balconies, verandas and raised platforms (above 300mm) do not fall under PD rights. You will also now need planning permission to construct a drive from non-porous materials such as tarmac. But you can construct a new drive of porous materials, or non-porous if provision for drainage is provided on the property, under PD.