Loft conversion

The new elements which help to form the new loft room(s) are broadly:

• Floor and beams
• Walls
• Doors

Floor and beams

It is unlikely that the existing ceiling joists will be adequate to support the weight (loads) that arise from the construction, contents and use of a typical habitable room developed in a loft. 

To overcome this problem, new floor joists would need to be installed to take these new loads. These can normally be placed between the existing ceiling joists and will probably be larger than the existing joists. If the existing walls are adequate then the new floor joists may be supported on them. 

Otherwise additional support – such as steel or timber beams – should be introduced which in turn will be required to be adequately supported and provided with fire resistance.

Walls

New walls will contribute to the perimeter of the new room(s) and will help support the existing and new roofs where existing roof supports have been removed. Such new support for the roof will normally take the form of low level walls towards the eaves of the premises, helping to reduce the span (unsupported length) of the existing rafters. Other walls, typically load-bearing, will separate the new room(s) from other areas of the home. These walls may need to be fire resistant.

Sound insulation

Sound insulation is required between habitable rooms. With a terraced or semi-detached house, the building control body may also ask for sound insulation between the converted loft and the neighbours loft to be improved. If they think it is necessary the building control body may also ask for a test to be carried out, but this will depend on the neighbours allowing access for the testers. The existing party wall will need to be upgraded to provide sound insulation between the properties.