Can I do my own drywall work in a Toronto basement apartment and still pass the building inspection?

Yes, there is no Ontario regulation that requires a licensed contractor to install drywall — a homeowner can legally do their own drywall work in a basement apartment. However, the work must meet every Ontario Building Code requirement, and the building inspector will hold your work to the same standard as a professional installation. The reality is that basement apartments (secondary suites) have some of the strictest drywall requirements of any residential project, and the inspection failure rate for DIY work is significantly higher than for professional installations.

A basement apartment in Toronto requires a building permit under the City of Toronto's zoning bylaws and the Ontario Building Code. You cannot legally create a secondary suite without permits for framing, electrical, plumbing, HVAC, insulation, and fire separation — and drywall is the component that ties all of these together. The inspector will visit at multiple stages, and drywall typically cannot be installed until the framing, rough-in electrical, rough-in plumbing, insulation, and vapour barrier inspections have all passed.

What the Inspector Will Check on Your Drywall

Fire separation is the most critical requirement and the most common inspection failure point. The ceiling assembly between the basement apartment and the main floor living space must achieve a minimum 1-hour fire resistance rating. This typically requires 5/8-inch Type X drywall on the basement ceiling, and in many assemblies, double layers of Type X. The specific assembly depends on your joist type (wood or engineered) and spacing. Every joint must be taped and finished, every penetration (light fixtures, smoke detectors, HVAC registers) must be properly fire-stopped with appropriate rated materials, and there can be no gaps or unsealed areas. A single missed penetration or unsealed gap fails the fire separation, and the inspector will require you to fix it before proceeding.

The walls separating the basement apartment from the furnace room, electrical panel room, and any storage areas shared with the main dwelling also require fire-rated drywall assemblies. If your furnace serves both units, the furnace room enclosure must be fully wrapped in 5/8-inch Type X drywall with a fire-rated access door.

Vapour barrier installation must be completed before any drywall goes up. Ontario's Climate Zone 6 classification requires 6-mil polyethylene on the warm side (room side) of all insulated exterior walls. The inspector will check that the poly is continuous, properly sealed at seams with acoustic sealant or sheathing tape, and sealed around all penetrations. Basement walls below grade must have a minimum R-20 insulation value. If you install drywall before the vapour barrier inspection, the inspector can require you to remove the drywall to verify what's behind it.

Sound separation between the basement apartment and the main dwelling must meet STC 50 (Sound Transmission Class 50) as required by the Ontario Building Code. This typically requires resilient channel on the basement ceiling with 5/8-inch Type X drywall, along with batt insulation in the joist cavities. The resilient channel must be installed with screws that do not penetrate the joists — if even one screw short-circuits the channel by hitting a joist, the sound isolation is compromised.

Ceiling height in the basement apartment must be a minimum of 1.95 metres (6 feet 5 inches) clear to the underside of any obstruction, including bulkheads, ductwork soffits, and beam wraps. This measurement is taken to the finished drywall surface, so the thickness of your ceiling drywall and any furring or resilient channel reduces the available clearance. In many older Toronto basements — particularly the post-war bungalows common in Scarborough, North York, and Etobicoke — ceiling height is already tight, and every half-inch matters.

Practical advice for DIY success: study the specific ULC-listed fire resistance assembly your plans call for and follow it exactly — no substitutions in board type, thickness, screw spacing, or layer count. Use setting compound (hot mud) for your bedding coat on fire-rated assemblies, as it provides a stronger bond than pre-mixed compound. Keep detailed photos of your vapour barrier, insulation, and fire-stopping before covering them with drywall — these serve as evidence if questions arise during final inspection.

The honest assessment is that while DIY drywall in a basement apartment is legal, the fire separation, sound transmission, and vapour barrier requirements make this a project where professional installation typically costs $5,000 to $12,000 for the drywall scope and dramatically reduces your risk of inspection failure and costly rework.