Additional fire protection may be necessary in the existing parts of the house. For example, a typical loft conversion to a two-storey house will require new fire-resisting doors, and sometimes partitions, to protect the stairway, as it is too dangerous to escape via windows from floors above first floor level.
Fire doors are life-critical. So it makes sense to use certified products. Certification schemes, like the BWF-CERTIFIRE Fire Door and Doorset Scheme and BM TRADA’s Q-Mark Fire Door Scheme, ensure doorsets are fit for purpose. See Timber Trade Topic No. 3 Fire doors & doorsets.
Mains powered, interlinked smoke alarms are also required within the stairway at each level; and you may need to upgrade the fire protection to some parts of the structure of the house, such as the floors, where building regulations require 30-minute fire resistant floors for loft conversions in homes of two or more storeys.
Building regulations require a minimum 270mm of insulation in the void between the floor joists (see adding larger, stronger joists above).
You can achieve acceptable sound insulation by using a wood-based board, such as plywood or 22mm tongued and grooved chipboard, weighing more than 15kg/m2 for the floor surface. With a terraced or semi-detached house, the building control body may also ask for improvements to the sound insulation between the converted loft and the neighbour’s loft.
A timber floor makes sense, as it is durable, easy to keep clean and good-looking. If you are laying a decorative timber floor, use an acoustic underlay. See Timber Trade Topic No. 15 Flooring for more information.
You should insulate your loft by insulating the roof itself rather than, or as well as, the loft floor. Use rigid insulation boards between the roof rafters, cut so they fit snugly between the rafters. They can then be covered by plasterboard, or timber panelling. Rafters aren’t usually very deep, so to get the best performance, you may have to insulate over them as well, using insulated plasterboard. If there isn’t room to do this, make sure you use the highest performance insulation board.
As well as adding character to a room, wood panelling can improve thermal and acoustic insulation and mask defects.
Many species are suitable, but pine and spruce are the most popular and are also available in a variety of pre-finished stains and finishes. Boards come tongued and grooved in a range of sizes and decorative profiles with thicknesses from approx. 7mm to 25mm. Boards thicker than 12mm provide additional structural strength. For best results use timber manufactured from higher grades and kiln dried to 8-12%.