External walls

Depending on the distance the wall will be from a boundary with an adjacent property, it may also need to provide resistance to fire (to limit the effects of fire spreading from or to adjacent properties).

The area of walls permitted to have reduced or undetermined fire resistance (known as "unprotected areas") - such as openings for windows or doors - will be dependant on how close these elements are to the boundary.

If the wall is also load-bearing, by virtue of supporting a roof or a storey above, it will also need to have fire resistance regardless of its distance from a boundary.