07 October 2008Means of escape in the event of fire
Means of escape in the event of fire is very important. There are many ways to achieve compliance, below are two possible methods:
This method creates a half-hour fire-resisting cell in the roof. This is in the event of fire, someone in the loft room can wait for rescue. This method required:
The door to the loft room can be at either the top or foot of the stair. If at the foot of the stair, then the underside and enclosure of the stair will need to be half hour fire protected. Two layers of 12.5mm plasterboard with staggered joins can achieve this.
Alternative means of escape must be provided to each new loft room to aid rescue.
A window is an acceptable alternative only if it is provided with an unobstructed operable area of not less than 0.33m², and has a minimum dimension of 450mm in either height or width.
The dimension of 1.7m from sill to eaves is to allow a person climbing from the window, to hang by their fingers across the slope of the roof and find the top of a rescue ladder with their feet.
The maximum sill height above floor is to ensure that a person can climb out of the window without too much difficulty.
The minimum sill height is to ensure young children do not easily get on to the roof slope. To meet this requirement suitable permanent child proof guarding could be erected. The loft window also allows the fire brigade to see into the loft room and determine if anyone needs to be rescued.
The position of the escape window is critical. Structures like sheds, conservatories, porches etc. can all make it difficult or impossible to allow the fire brigade to pitch an escape ladder up to the window. These factors must all be considered before the window can be installed. Even after the work is complete these factors must be considered, particularly if an extension or other structure is erected that may compromise escape from the loft room. Building control will be able to advise.
This method does not require any special fire provisions to the loft room. However, all doors off the new and existing stair must be half hour fire resisting and be fitted with self-closing devices. Existing doors can be upgraded but often this is not possible and new fire door is used.
Route to open air
With both of the above methods, the escape route from the new loft room must have a half-hour’s fire resistance to its floor. Also, the route must not pass through any room or have any room not protected by a door opening on to it.
Note: at ground floor level it is acceptable for the escape route to pass through a room, provided there are at least two alternative fire resisting routes from the enclosure, and all doors on to the escape route are self-closing 20 minute fire resisting doors.
There will be problems if there are large landings to a stair, or if the stair opens directly into a room not separated by a door etc. If this is the case, you should contact your Building Control Surveyor to discuss this before starting work.
Also, any glazing to walls or doors (generally not external windows, wt’s or bathrooms) on the stair must be replaced with fire resisting glass in a suitable beading system.
Final exit
A final exit is one which leads to open air and not into an enclosed area. It is not acceptable to escape into a fully enclosed courtyard or garden.
Fire resistance to the loft room floor
This can be achieved in many ways. Regardless of the method selected, each must be applied to the whole of the first floor ceiling and not just the area under the loft room The fire resistance can be achieved in many ways, two of which are:
Two layers of 12.5mm plasterboard can be fixed form underneath. The existing first floor ceiling may already be plaster boarded, so only one additional layer may need to be fixed.
If the existing ceiling is plaster on timber lathes, then any plasterboard under will actually fail faster due to the weight of poorly bonded plaster pressing on the back of the new plasterboard. If this is the case, a composite floor method could be better.
A metal wire basket (chicken wire) must be securely fixed between the floor joists as close to the existing ceiling as possible. This basket is lined with at least 60mm of mineral wool. This insulates the room above from the heat of the fire and non-combustible wire prevents the mineral wool falling out should the ceiling give way. Gaps between the existing ceiling joists must be well packed with mineral wool to stop smoke or flame.
External fire spread – dormer windows
If a dormer window is used, the sides of the dormer will need to be made fire resistant to prevent fire spread between properties. This must be done both internally and externally. Usually two layers 12.5mm plasterboard is sufficient internally. Externally it may be necessary to use a fire resistant board under the waterproof covering e.g. tiles.
Fire precautions and home insurance
Some of the requirements laid down by the Building Regulations may seem onerous, but they are designed to protect the occupants in case of a fire. If fire precautions are removed after a Building Regulation completion certificate is issued, this may void insurance held on the property in the event of a fire.
