Basement Drywall & Second Units · Kitchener
Basement Drywall and Legal Second Units in Kitchener
In a basement suite the drywall is not the finish. It is the fire separation the inspector signs off, and everything about how it is hung follows from that.
Most of the second-unit work in Kitchener is in the post-war bungalows and side-splits through Mount Hope, Cedar Hill, Mill-Courtland, the East Ward and the streets around Victoria Park, where a full-height basement and a separate side entrance make a legal unit practical. The City's duplex construction guide is the document that governs the drywall, and the inspector will have it in mind when they look at the ceiling.
What the ceiling has to be
The approved drawings specify a 30-minute or 15-minute fire separation between the units. For 30 minutes, the floor-ceiling assembly gets one layer of 15.9 mm (5/8 in) Type X or 12.7 mm (1/2 in) Type C board on the underside of the joists. For 15 minutes, one layer of 12.7 mm regular board — but a 15-minute separation then requires the smoke alarms in both units to be interconnected. Walls between the units, and between a unit and the shared entry or furnace room, get 12.7 mm board on both sides of the studs. Those are the City's figures; the drawings for your house decide which applies.
Continuous means continuous
The guide is explicit that the separation has to be a continuous barrier, and this is where basement suites fail inspection. Board stopped short at a bulkhead, a gap above the top plate of a partition, an unboarded joist space behind a beam, or a recessed light cut in after the fact all break the barrier. Where a range hood, dryer or bathroom exhaust duct or a plastic-backed pot light is too large to fire-stop, the guide calls for a drywall box built inside the joist cavity around it. Planning those boxes and bulkheads before the first sheet is hung is most of the skill in the job; cutting them in afterwards is slow and rarely clean.
The older basement problems
- Height. The provincial guide allows a basement unit ceiling of 1.95 m across the required floor area. A beam, a duct trunk or a drain line can push a bulkhead below that in a 1950s basement, and the layout has to be worked out so the required area clears it. Furring the whole ceiling down to hide services is not available when the height is already tight.
- Uneven walls. Block and rubble foundations are rarely plumb or flat, so the framing is shimmed and strapped to give the board a true plane. Board follows framing; it does not fix it.
- Moisture. Efflorescence, a damp corner or a floor that sweats in August is dealt with before anything is boarded. Drywall tight to a wet foundation wall is a mould problem with a finish on it.
- Sound. The guide notes sound control between units is not required by Code for a second unit in an existing house but recommends it. Resilient channel under the ceiling board, insulation in the joist space and a second layer of board are the usual steps, and this is the moment to do them — not after the tenant moves in.
Sequence and inspection
Framing, insulation and the fire separation are inspected before the joints are taped, so the boarding is scheduled around the City's inspection and the finishing follows it. The permit is issued to the owner before any of this starts; a legal unit built without one is not a legal unit, and the City's ADU guide is plain that adding units always requires permits.
Frequently asked questions
Do I need Type X everywhere in a basement apartment?
No. The City's guide calls for Type X or Type C on the ceiling for a 30-minute separation, and 12.7 mm regular board on the walls between units. A 15-minute ceiling can be regular board if the smoke alarms are interconnected. Your approved drawings say which rating applies, and we build to those.
Can you leave the pot lights the previous owner installed?
Only if they do not break the separation. Plastic-backed recessed fixtures in a fire-rated ceiling generally need a drywall box built around them in the joist space, or to be replaced with fixtures rated for the assembly. That gets settled before boarding, not discovered at inspection.
Will the City inspect the drywall itself?
The fire separation is inspected before it is taped so the inspector can see the board, the joints and the boxing. We schedule the finishing after that visit and leave the assembly open until it passes.
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