Loft Conversion

Things to consider

The first thing to decide when considering a loft conversion is what sort of loft conversion do you want? What will you use the extra space for? It could be simple storage, or a bathroom or shower cubicle. Alternatively you may want a studio for painting or photography, a dark room, an office, play room or extra bedroom(s) with or without en suite. There are many possibilities. You need to know what you will want to use the additional space for to come up with the right design.

A loft conversion which uses the space already available is called a roof light or velux conversion. If the conversion includes a roof extension, it is known as a dormer conversion.

You will need to know whether your loft is suitable for conversion. You should consult an architect to establish this, but you can do some initial investigations yourself. Firstly, go into the loft and look for wet or dry rot. If there are any signs of either of these they will need to be treated first. You should then check the overall size of your loft, and the space between the purlins (horizontal beam which supports the rafters) and other parts of the roof structure. If there is 3 metres between the main purlins on each side of the roof, the loft may be suitable for conversion. If there is less you may still be able to have a loft conversion but may only have enough space for stairs and a small room such as a bathroom or office.

If your house was built after 1964 you will need to look at the construction of the roof. If it has trussed rafters, a loft conversion may still be possible, but will be more complicated as the roof will have to be raised, or the timbers rearranged.
Suitable Loft Conversions

A trussed roof is made of factory assembled triangles. It has rafters attached to ceiling joists by galvanized steel tie plates, and with a higher number of struts.


The next thing to look for in your loft is bats. The usual evidence that there are bats living in your roof is the presence of their droppings. Bats and their roosts are protected under the Wildlife and Countryside act 1981 and the Conservation (Natural Habitats etc.) Regulation 1994. By law you must obtain advice from English Nature, Countryside Council for Wales, Scottish Natural Heritage or Department of the Environment (Belfast) for advice on protecting the bats and their habitat before you start work. This applies not just to the bats themselves but to their habitat, so if there are no bats actually living in your roof at the present but there are signs it has been used previously you must still inform the authority for the area in which you live. Do not attempt to catch the bats yourself as some of them carry a rare form of bat rabies for which there is currently no cure.


Loft and Basement Stairs Once you have checked out your loft, you need to consider where the new staircase will be located. Ensuring there is enough headroom is critical. You want to avoid the new stairs looking like an add on and the stairs should be in a similar position and of a similar design to the original. In some cases it is necessary to lose a room, or part of a room from the existing building to accommodate the staircase to the new storey.

New floor joists may be required on the existing 1st floor may need upgrading to ensure they have 30 minutes of fire resistance.

Informing others

Check whether there are any covenants imposed on your property, restricting the work you are able to do on your home. It is also wise to consult your neighbours and tell them your proposals. If your loft extension overshadows a neighbours window or gives a view into their garden which you did not have previously they may have cause to complain. They are likely to be concerned whether the work you are doing will affect them, just as you may be concerned if they did any work which might affect you. Disputes can often be avoided by discussing the issues at an early stage and putting everybody’s mind at rest.


Planning Permission

Many loft conversions do not need planning permission at all. However you should obtain advice as you may need it in your case. Some examples of those which require planning permission are:

  • if the loft conversion changes the outside appearance of your property
  • if the new room(s) will constitute a change of use, for instance an office
  • if the volume of the extended roof exceeds 40 cubic metres for a terraced property and 50 cubic metres for a semi detached or detached house
  • if the loft is converted into more than two habitable rooms
  • if you live in a conservation area

An architect will be able to advise you on whether you need planning permission, or you could contact your Local Authority yourself. Our Council Links page will direct you to your own Local Council’s website for more information on planning regulations in your area. If you need to apply for planning permission the Planning Department will require several copies of your drawings and a fee. Then your planning application will be placed on the Planning Register ( which is available for members of the public to view) and your application will be published in the local press. You should receive a decision from the Planning Department within eight weeks, or if it will take longer they should write to you and and ask for an extension of time.

Building Regulations

Even if planning permission is not necessary, the design of your loft extension must meet building regulations. These cover such things as fire escapes, ventilation, and, if the property is semi detached, sound insulation

Party Wall legislation will need to be considered. In principle you can do work on a party wall, but the adjoining owner needs at least 2 months notice before work commences.

The Building Control Department of your Local Council will require several copies of all your drawings. Your application will be placed on the Building Register. There will be a fee for this. Any member of the public may look at the register and may lodge an objection. You should receive a decision from the Building Control Department within five weeks.