Loft conversions are one of the most popular types of home improvement project, as they can provide a household with extra space without any need to add onto a building.
Because there is no physical alteration to the outside of the building, planning permission is not usually needed. But a number of limits and conditions do apply, which are mostly designed to ensure that a loft conversion is structurally safe, and can be expected to take a reasonable amount of weight.
Meeting the following conditions will help ensure that your loft conversion meets all the planning authority's requirements for being structurally safe:
- If it is being added to a terraced house, 40 cubic metres of roof space must be available to accommodate the loft
- If you are carrying out the conversion in a semi-detached or detached house, this minimum space allowed rises to 50 cubic metres
- The conversion must not reach higher than the plane of the existing roof slope of the main elevation to the house which faces the road
- Choose materials which are similar in look to the existing parts of the house
- Do not fit any verandas, raised platforms or balconies to your loft conversion
- Any side-facing windows must be glazed with opaque or obscure glass, while any openings of these windows have to be 1.7 metres (66.9 inches) above the floor
- Roof extensions are not allowed in designated areas – which include conservation areas, areas within national parks, and world heritage sites
- Wherever practicable, all roof extensions should be set back from the original eaves by at least 20 centimetres, except for those built from hip to gable
Importantly, existing roof space additions have to be taken into consideration when calculating whether any new development meets the maximum volume criteria.
If you are adding a loft conversion to a bungalow, it's particularly important to check whether the building's structure is strong enough to take the extra weight, so in these instances, you should hire a professional surveyor to determine whether this is the case.
Further restrictions apply if you are going to install a new bathroom in your converted loft, so you will need the help and advice of a qualified plumber to ensure that your new addition meets all building regulations.
Surveys have shown that the average cost of a loft conversion is in the region of £16,000, but can be considerably higher, depending on the scale of your project. So it pays to get a number of quotes for your conversion, and you should always ask any firm you approach to provide details of their insurance cover, and for references provided by previously satisfied customers.
A company's experience and track record is often the best guarantee you can get, but also make sure that you get the extra help mentioned in this post to satisfy yourself that you are dealing with a legitimate company whose work will benefit you while you are living in the house, and also be an asset if or when you come to sell it.
SOURCES: London Borough of Redbridge Building control guidance note 3 – loft conversions and sound insulation requirements (pdf). http://www.planningportal.gov.uk/permission/commonprojects/loftconversion/