Geoff Wilkinson looks at the fire safety rules relating to alterations to offices
One of the questions we regularly get asked is whether or not Building Regulations apply to minor works to fit out offices, shops, and so on. In most cases the answer is ‘yes’ and there are quite a few regulations that you can fall foul of if you are not careful.
It will come as a surprise to many architects that even a simple project to subdivide an office can require building control approval. This is because the regulations apply to any alteration that affects the means of escape in case of fire, even if it there is no structural work proposed. Conversely, taking down partitions to make an open plan office can also require permission, as the partitions may have formed a means-of-escape corridor or other form of protected escape route.
Partitions fire safety
A typical scheme might involve creating a new office or meeting room within an existing open plan layout. This is known as an inner room, and specific rules apply, as the only escape route is through another room and a fire in the outer room could trap someone inside. Therefore, Building Regulations require that:
- the capacity of the inner room does not exceed 60 people (which could rule out meeting and conference rooms)
- the escape route from the inner room should not pass through more than one outer room
- the travel distance from the inner room to the exit(s) from the outer room should be limited (usually to 18m in total)
- the outer room should not be a place of special fire hazard
- the outer room should be in the control of the same occupier; and
- in order to give early warning of a problem, either
- the partitions of the inner room should be stopped at least 500mm below the ceiling, or
- a vision panel not less than 0.1m2 should be located in the door or walls of the inner room, or
- the outer room should be fitted with automatic fire detection which is audible within the inner room.
Other considerations include:
- changes to the emergency lighting and fire exit signage may be required
- changes to sprinklers or fire detector locations may be required
- wall and ceiling linings should be controlled and the surface spread of flame rating limited.
Note that if you are dividing a floor into separate occupancies, the means of escape from each occupancy should not pass through any other occupancy. If the means of escape will then include a common corridor or circulation space, then either it should be a protected corridor or a suitable automatic fire detection system should be installed throughout the whole of the storey.
Therefore plans should always be prepared for building control approval which show the following: proposed uses of each space; fire escape routes; fire compartmentation; cavity barriers to floors and ceilings; fire rating of doors and partitions; proposed ironmongery; fire alarm layouts; exit signage; emergency lighting; and sprinkler layouts (these are often best shown on a reflected ceiling plan).
Geoff Wilkinson is managing director of Wilkinson Construction Consultants www.thebuildinginspector.org
This article originally appeared in the June issue of AJ Specification