Fire Resistance Ratings
For Single Family Houses, there are usually no Fire Resistance Ratings
(FRR) required for the
walls. The exception to this is where you have a wall in close proximity to
a property line or where you have a party wall separating one dwelling unit
from another. The building code deals with this in more detail but in
Ontario (and most of Canada) where you have buildings close together (in
cities and suburbs), the exterior walls require fire ratings when they are
in close proximity to the property line (usually around 4 feet (1.219 m).
If
a
wall is less than 4 feet away from a property line, there are no windows
allowed. If the wall is less than 2 feet away from the property, the
exterior cladding needs to be non combustible and the interior cladding
needs to have a 45 minute FRR
It can get complicated. Even though we often consider a wall to be a
vertical element, we often overlook or do not consider the make up of a wall
assembly and the various components that are required to build it. When
specifying a material for a wall assembly, there is often a large area over
which that detail applies. This is why the sandwich of materials that make
up a wall need to be carefully considered by design. It might not look like
a lot as a small note on a wall schedule or a discreet line on a detail, but
is is a lot when that detail is extrapolated over a large area (like a wall
face). Small changes can have a large effect.