Things to consider
Loft Conversions are a popular way of getting more space in your house or top floor flat. But one way or another you will need to get the Councils permission, so before you start you need to consider whether your house is suitable and the likelihood that your plans will meet the Councils requirements.
You will generally need planning permission if the house is in a conservation area and you will be altering the shape of the roof. Outside a conservation area you must get planning permission to extend the front of the roof or raise the height of the ridge or if you are extending the roof by more than a certain amount. You should always check first with the Councils Borough Planners service to find out whether you will need planning permission for your project.
You will certainly need building regulations approval and the Councils Building Control department will tell you what is required and how much this will cost, the building regulations impose certain structural and other requirements particularly when it comes to access stairs and this may limit the options available to you, but in meeting these requirements the result may be a conflict with planning objectives concerning the external appearance of the proposed extension. It is important to find out as early as possible, as it may mean you will not easily get planning permission.
Is the loft space large enough?
Some roof types are generally more suited to conversion than others in terms of size, shape and construction. Some roof types are easier than others to convert.
Ideally, your existing loft should be large enough to accommodate the room (s) you want without any need for major extensions. All you should then need are dormer windows- i.e. windows inserted into the sloping roof to light the space inside – or even just a roof-light.
More often though, roofs are extended to create headroom where none exists at present. Generally, there is not minimum ceiling height requirement in the Building Regulations, but a ceiling height lower than 2.1m (7’0”) will seem cramped. Remember also that a new structural floor and roof will have to be built and this means that the finished headroom will be about 300mm (1.0”) less than the headroom you have in your loft at present. To achieve a reasonable amount of space with adequate headroom may meant major alterations to the loft which could alter the look your house quite dramatically. This could mean that the project would be ruled out because of its poor appearance.
If you have a modern house with a trussed roof construction it may be possible to convert the lost space but you may find that it will be a complicated and expensive job.
Some shapes are more sutable than others
Plenty of Existing Headroom
This style would be suitable for a conversion and no need for a large space making extension
Because of the shallow roof pitch the roof space and headroom are poor in this style of loft
The amount of usable floor space is very small
A major extension would be needed in order to convert this loft, and is unlikely to get planning permission
How will access be gained to the loft space? On the case of many semi-detached and terraced houses the existing stairs are located beside a party wall. This means that the mot efficient and logical location for the new stair into the loft is also against the party wall, since the new stair must rise into that part of the lost where there is least head-room, it will be necessary to provide an extension to the roof right against the party wall. This is something we try to avoid because the extension would almost certainly look bulky and out of proportion to the roof.
The most common problem is the need to extend the roof to accommodate the new access staircase and meet Building regulation requirement for headroom over the stairs of at least 1.9m. Often this depends on the shape as well as the height of the existing roof.