Habitable Basements

Ensure that the basement is separated from the ground floor by 30 minute fire-resisting construction. The soffit and spandrel to the ground to first floor staircase to be of minimum 30 minutes fire-resisting construction. (sound existing plasterboard or lath and plaster ceilings will be acceptable, but unsound ceilings should be replaced or under-drawn with fire-resisting materials designed to provide an adequate standard of insulation to avoid the unexposed side of the element becoming hot enough to ignite material in contact with it ; and sufficient integrity to avoid the formation of openings or cracks in the element that could allow flame or hot gases to pass through it, to ignite materials on the unexposed side of the element .

The door at the head of the basement to ground floor staircase to be of 30 minutes fire-resisting construction from either side. The door to be properly fitting, with no more than a 4mm gap around it, hung on three metal hinges, in a sound door frame with 25mm door stops, fitted with a top of door hydraulic door closing device capable of over-riding any latch and fitted with suitable intumescent strip/smoke seals around the upright and top edges. The door threshold to be sealed by a flexible edge seal just contacting the floor, but not exhibiting significant increased frictional forces capable of interfering with the closing action of the door, or a maximum 3mm gap at any point. If the door cannot be determined that it meets the requisite standard, it must be replaced with a door that complies with this paragraph. If the frame is out of square, insecure or damaged it should be replaced, and any gaps between the frame and adjacent wall construction to be filled with intumescent material. If the door is fitted with a vision panel, the glazing must not reduce the level of fire resistance. Any locks fitted to the door to be capable of being operated, without use of a removable key (turn-key) from the habitable side facing the basement.

Provide a separate exit leading to an ‘ultimate place of safety’ from the basement which is capable of preventing unauthorized entry to the building, but has any locks capable of being operated from the inner side without use of a key. (N.B. Ultimate place of safety is the street, or location at a distance at least as equivalent to the height of the building away from the building).

Provide an escape window to each habitable room within the basement. Any escape window provided for emergency escape purposes should have an obstructed openable area that is at least 0.33m2 and has a minimum openable height and width of 450mm. The window should be secure against unauthorized entry, but should not be fitted with removable key operated locks. The window sill must not be more than 1,100mm above the room floor. There must be no basement well or other encumbrance beneath the window such as railings or a conservatory and the window should lead to a place of ultimate safety.