Canada Builds

Walls

Walls are an integral and vital element of a building in terms of function and design. The make up and construction of a wall is also important and this is where many designers can stumble. In a design sense, the wall is considered as a planar element or a rectangular cube. In a technical sense, it is comprised of any number of layers or assemblies. Choosing OSB instead of Plywood as a wall sheathing reduces costs but may not be as durable. Masonry will last much longer than wood but it costs more to build. Wood is easier and less expensive to build but it will not last as long as masonry. These are examples of some of the issues and questions you will contend with when thinking about how a wall is made.

House Frame by John Boone Architect on Sketchfab

As a benchmark or point of departure, consider the Building Code as a minimum standard for the functional criteria that a wall must achieve. In this section of the site, a number of different wall types and wall sections are portrayed with details and commentary. For some walls, there is a need for fire ratings meaning the wall needs to fend off the effects of fire for a period of time. Typically, these ratings will be specified as 30 min, 45 min, 1 hr up to 2 hours depending on the application. For other walls, the requirement is more for the purpose of providing insulation between the inside and out. Blocking sound, blocking water, mitigating vapour, holding up a floor. Theres a lot going on when considering a wall.

Wall Types

 

Wall Types are typically indicated in a schedule of some description. The wall tag is then used throughout the set of drawings to indicate the wall type. This method reduces the possibility of error with regards to the make up of a wall type because the material assemblies only have to be indicated once (in the wall schedule). If something changes, such as the removal of a plastic vapour barrier in favour of a vapour retardent paint, the note only has to change on the wall schedule. The wall type is still the same: W1, W2, and so forth.

 
   

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).