Where a steel-framed building is to be situated close to the boundary with another property, i.e. land that belongs to somebody else, then a ”boundary condition” may apply. If a wall of the building is between 1m and 5m from the boundary, then Building Control may ask for 1-hour firewall protection to that wall. This means that the wall panels will need to be upgraded to a fire-resistant version and that the frame will have to be specially designed so that when it collapses (after at least 1 hour) it will collapse inwards, away from the boundary: The building inspector is entitled to insist on firewalll construction if the building is within 25m of a boundary, but most inspectors would not go this far. Provision of firewalls imposes a modest increase in cost.

If the building is to be less then 1m from a boundary a 4-hour firewall will be required, under these circumstances the usual solution is to use brickwork or blockwork for the wall.

Whenever a building is close to a boundary it should be borne in mind that access will be needed in order to clad it. The minimum requirement is at least 1.5m of level hard standing; in the case of tall buildings, more clearance may be required.