Attic / Roof Space access
A HOMEOWNER’S GUIDE
Attic access is an essential part of any house framing. Although it’s easy to get done, sometimes it’s left out during the initial stage of framing. Without proper attic access, your house will not pass the framing inspection.
Even if there was no inspection at all, attic access is still very useful and important. You need access to your attic space in order to annually check and inspect for any roof leaks, mold, condensation, ductwork (that usually runs above the ceiling between the trusses), air vents, insulation, etc.
Even though attic access is very useful, a poorly built hatch can become one of the significant sources of heat loss and create condensation in the attic. As we know, air has a tendency to rise higher as it gets warmer and is replaced by cold outside air, which you might notice as a draft that enters below the front door.
Often, attic accesses are no more than a piece of painted plywood on a couple of cleats.
It can be difficult for homeowners to recognize how much conditioned air escapes through an attic access, or they rarely connect the cold drafts on the first floor of the house with the attic access upstairs.
However, this hole in the highest part of the ceiling can allow a tremendous amount of heated air to escape into the attic. This heated air is replaced by cold outside air, which you might notice as a draft that enters below the front door.
To avoid this situation and achieve maximum energy efficiency, you can install an insulated attic hatch.
Framing Attic Access:
An attic hatch is usually installed between two trusses. A 24 inches On Center (OC) truss layout allows you to install the attic hatch without damaging any trusses. The 24'' OC truss layout space between the trusses is 22 1/2 inches.
The Ontario building code requires that the dimensions of the attic access should be no less than 21 5/8 by 35 1/2 inches. The height (going vertically from the ceiling up) of the shaft should be no less than 24 inches, in order to allow proper insulation. This means that you can perfectly fit your attic hatch between the trusses without damaging or modifying them.
Important Note: Modifying or cutting pre-manufactured trusses without an engineer's approval is strictly forbidden. It can significantly damage the structural integrity of the whole roof structure.
If you want to know more about pre-manufactured roof trusses, you can read our article about roof truss systems.