Building regulations requirements for a loft bedroom
Using a loft as a bedroom requires compliance with Part B (fire safety) and Part A (structure) of the Building Regulations. The key requirements are: (1) Escape from fire — the building regulations require that a person trapped in a loft bedroom must have a means of escape in case of fire. On a two-storey house, a loft conversion creates a third storey, and the existing staircase must be enclosed in fire-resistant construction (a 'protected staircase') with fire doors, or alternatively a mist sprinkler system can substitute. (2) Egress window — every habitable room in a loft must have at least one opening window with a minimum 550mm height and 450mm width clear opening, positioned with the opening cill no more than 1.1m above the floor, and the window at least 800mm above the outside ground level (for safety). (3) Structural floor — the new floor must be designed to carry 1.5 kN/m² imposed load (habitable use), calculated and signed off by a structural engineer.
Fire safety requirements for a loft bedroom
Fire safety is the most important aspect of a loft conversion for bedroom use. The requirement (Part B, Building Regulations) is that every escape route from the loft bedroom to a place of safety must be protected from fire. In practice, this means: all doors opening off the staircase (from ground floor to loft) must be FD30 fire-rated self-closing doors; the staircase itself must be enclosed in fire-resistant construction (30-minute fire resistance); smoke alarms must be installed on every floor and in the loft, all interconnected (so an alarm on the ground floor wakes someone in the loft). For buildings with more than two storeys (a house plus a loft), this protection must extend from the loft down to the ground-floor exit — converting the existing ground-floor hall into a protected stair corridor, which means replacing any conventional doors with fire doors. An alternative is a residential sprinkler system (BS 9251) which can substitute for the protected staircase requirement in some configurations.
