A guide to loft conversions

If you’re thinking of converting unused attic space to extend your home, this page may answer some of your questions. For any use other than light storage you will need to tell the Building Control Section who will advise you on what you need to do.

The Party Wall Act 1996 may also apply if you intend to carry out work which involves:

  • Work on an existing wall shared with another property
  • Building on the boundary with another property
  • Excavating near a neighbouring building

You must determine whether the works fall within the scope of the Act, and if so, you must serve statutory notice on all those defined by the Act as ‘adjoining owners’. You may wish to seek professional advice on this.

Also see Building work near boundaries and neighbours

  • Make a plan of what you want done. Don't be pressured into unnecessary work or work you can’t afford. For large or complex jobs, professional advice may well be needed.
  • Get the necessary consents or agreements from the council and insurance company. Discuss your plans with neighbours, particularly if there are party structures.
  • Draw up a short list of firms that appear reliable, checking references from previous clients, and perhaps references from banks as appropriate.
  • Find out whether a worthwhile guarantee is available giving cover against a contractor ceasing to trade. Insurance-backed schemes may be particularly appropriate.
  • Warranties are available in partnership with the council’s Building Control section.
  • Be as clear as possible about the way you will deal with any disputes.

The Building Employees Confederation (BEC) also offers advice to help you in 'Get the best from your builder'. Also see Choosing Your Builder.

We are responsible for enforcing Building Regulations, which make sure that buildings are constructed or altered to reasonable standards and are safe. In the case of loft conversions the following are examples of the things that you and/or your builder must consider.

  • If the space is for a use other than light storage, it will need a new floor. New joists will have to be installed and these must be supported and kept clear of the existing ceiling; they are not allowed to rest on the existing ceiling joists.
  • The existing foundations and lintels may need to be exposed to check they can carry additional loads. The floor and supporting structure may need new beams or steelwork to support the loft conversion. You may need structural calculations to make sure these elements are adequate.
  • The Building Regulations require floors and certain walls/doors to resist fire for a specified period. In houses up to three storeys this is usually 30 minutes. If a fire was to occur in the house it is important that the occupants could escape safely, so escape windows are required.
  • In order to prevent unpleasant living conditions, ventilation has to be provided to habitable rooms, bathrooms and kitchens. The regulations require either background (trickle) or rapid ventilation, or in certain circumstances, both.
  • Condensation can also affect areas that cannot be seen such as roof spaces. If this is excessive and remains undetected it can cause problems. Ventilation must be provided to roof spaces and this is particularly important in loft conversions.
  • You will need to think about the type of stair you would like to use to get to your new room. Ideally, you should have a traditional stair that will give safe and easy access and allow you to escape quickly if there’s a fire.
  • The walls and roof to the loft conversion must, as well as keeping out the elements, also keep in the heat. They have to be constructed of materials that help reduce heat loss which can help keep heating costs down.

Remember that the council is here to give advice. The Building Control Officer responsible for your area will be happy advise you on the procedures to follow.

If you decide upon a loft conversion (or any other type of building work) you need to tell the Local Authority by submitting an application form, giving them either Full plans application or a Building Notice.

If you choose the option of providing a Building Notice then you may need to provide additional information about specific elements of construction where the nature of the work may be complex or unusual (e.g. in the case of a loft conversion, structural engineers calculations are often required for dormer roof and floor structures).

A delay in supplying information can slow the progress of work on site, so we strongly recommend that design solutions are agreed before you start work.

How you go about converting your attic will depend on what you want to use the space for. Some of the things you’ll need to think about are:

  • Will I need a new floor?
  • How will I get to the new room?
  • Do I want rooflights or windows fitted?

Loft conversions are generally carried out to provide:

  • an extra bedroom (maybe with en-suite)
  • a playroom
  • a study/office

If you plan to use the attic space to store light items (e.g. suitcases and Christmas decorations) then loose boarding is usually satisfactory. Remember that the ceiling joists are intended fix the ceiling below and are not designed to take heavy loads. To prevent any overloading of the ceiling joists, loose boarding shouldn’t cover more than 50% of the usable area.

‘Usable area’ is the part of the roof space with a headroom greater than 1.5m (approximately 4'6"). Access to this storage area is often by a retractable ladder.

For any use other than light storage you will need to tell the Building Control Section who will advise you on what you need to do.