Can drywall go straight over the vapour barrier in an Ottawa wall?

Yes, drywall goes over the vapour barrier. The vapour barrier sits on the warm side of the wall, and the board is installed over it.

Ontario's Building Code (9.25.4.3) says products installed as the vapour barrier protect the warm side of wall, ceiling and floor assemblies. These are minimums for new work; ask the City how they apply to your renovation.

The vapour barrier has to be in place and intact before the board goes up. If the barrier was damaged during framing, insulation or any other work, those gaps need to be addressed first. Insulation type, R-value and how the barrier is installed are outside what this site covers; ottawainsulationcontractors.ca handles that side of the work.

On permit work, the City's inspection stages include insulation and vapour barrier before the board goes up, and the City says missing an inspection may mean having to uncover and expose the work. Ask who books that inspection before the board is delivered.

The Code also wants penetrations through an air barrier, such as electrical boxes, wiring, piping or ductwork, sealed (9.25.3.3.(6)), so ask how boxes and pipes through that wall will be handled before the board covers them.

What the drywall quote should state:

• the board and its thickness for each wall
• that the board goes up only after any required inspection of the insulation and vapour barrier
• how openings for boxes and pipes are cut and sealed
• the finish level, the coats of compound, sanding, and primer in or out

Have the contractor put the finish level, the number of coats and whether primer is included in writing before work starts.