Converting a loft space into habitable accommodation needs careful planning as regulations such as fire protection, means of escape, head height and structural loading on the existing building will become key considerations.

Also, as timber roof structures are normally formed in a series of triangles i.e., rafters cross braced (tied) together beneath the ridge board are afforded additional support from purlins (horizontal timbers about mid-span), which then gain secondary support from binder timbers that usually bear down onto the spine partition wall (load-bearing wall that provides secondary support for the roof structure).

Any loft conversion is major work. When removing binders and raising or removing cross-bracing, the dead weight of the roof will have to be re-distributed to other parts of the building capable of taking the stress.

The general rules of thumb are that...

• The existing ceiling joists of bedrooms will not be of suitable load-bearing capacity to form the floor joists of a new structure.
• You will have to create a new floor structure over or in replacement of the existing. Usually by installing steels from the two outer walls then insetting new timber floor joists either in the web of the steel if head height is a problem or on top of the steel.
• Where the triangular structure of the roof is dismantled then perhaps a fixed steel ridge for the roof will be required set into the two outer brick walls. Rafters will have to be cut and packed into the web of the steel and bolted.
• You may need to provide windows that can be climbed out of in case of fire and fixed ladders on the outside of the building to a safe escape route.
• Fire containment of the staircase rising to the loft room together with a small fire protected landing will be required (either lobby and fire doors at the top if you want an open staircase, or the entire staircase with lobby and fire doors at the bottom).
• Floor joists around the head of the staircase will need to be double-braced to provide adequate anchorage for the staircase.
• Any installed staircase must have stairs of equal height.
• The room will need to have a minimum head height of 2m.
• You may need to upgrade the glazing to any door off the hallway to ½ hour fire glazing.
• Where windows are below 1m above floor level an internal horizontal bar will need to be installed.
• A pump may be required to get adequate water pressure at roof level for shower rooms etc.
• Existing stack pipes that vent at roof level will probably need to be raised to take smells at least 1m above any windows.
• You may need to install a fire alarm system throughout the property.
• You may need to provide a mains wired smoke alarm to the new room and hallways below.
• The exact requirements will depend on the design and site conditions and the building regulations in force at the time of making an application. Please refer to your local authority's building control department.