Insulation Installation Inspection Checklist (Ontario): What to Check Before the Drywall Goes On and Before the Balance Is Paid, for Batts, Poly, Blown Attics and Spray Foam

Before anyone starts: the four stops

Some things are checked before the first bag is opened, because once the insulation is in they are buried. Vermiculite, the grey-gold pebbly fill in attics from 1940 to 1990, is left alone until a lab test says what it is, and nobody blows anything over it. Wet or mouldy insulation is removed, not buried under new insulation; a damp batt under a fresh R-40 is a mushroom farm with a roof. Insulation is never placed over or against knob-and-tube wiring; the Ontario Electrical Safety Code does not allow it and most insurers will not cover the house. And non-IC pot lights, chimneys and B-vents need their clearance, 3 in. from a masonry chimney and a cover or a new IC fixture at every light, before the blower runs.

If the installer did not raise any of these on the site visit, raise them yourself. Vermiculite and knob-and-tube each have a page, because each one changes the job before it starts.

Batts in open framing, before the poly

1. Full depth, no compression. An R-22 batt is R-22 at 5.5 in. Squashed to 4 in. behind a wire it is about R-16, and the air space in front of it is a convection loop. Batts sit flush with the stud face, not bulging past it and not sunk behind it.
2. Cut to fit, not stuffed. A 2×6 bay at 16 in. on centre takes a 15 in. batt. Around a pipe, the batt is split and one half goes behind. Around a box, it is cut out, not pushed back. A batt folded to fit a narrow bay has a cold triangle on each side of it.
3. No gaps at the plates and corners. Hold the flashlight at the side of the bay and look along it. A 1 in. gap at the top plate is 2% of the bay and far more of its heat loss, because warm air convects into it.
4. Behind every tub, shower and stair stringer on an outside wall. These are insulated and air-sealed before the tub goes in, and then they are gone. If the tub is already in and the wall behind it is bare, that is a cold shower every January for forty years.
5. The rim joist bays, insulated and sealed, by foam at $5.50 a foot or by cut foam board and sealant. Batts stuffed into a rim joist dry are the leakiest thing in the house with a sweater on.

Poly and the air barrier, before the drywall

The 6 mil poly on the warm side of a frame wall is the vapour barrier by OBC 9.25.4 and, if it is sealed, the air barrier by 9.25.3. Sealed means a bead of acoustical sealant at every lap over a stud, at the top and bottom plates, around every electrical box with a poly hat or a gasketed box, and at every window and door frame. Lapped and stapled is not sealed. Run your hand along a lap; it should be stuck down with the black goo, not loose plastic over a staple line.

On a basement wall the poly question has its own answer and it is usually “not there”. A batt against concrete with poly over it is the wall that goes mouldy; the basement vapour barrier page has the fix. On an ICF wall there is no poly at all; the foam is the vapour retarder, and the only poly in the houses I build is on the ceiling under the roof structure.

Blown attic, before the truck leaves

Go up the ladder with the flashlight; do not sign from the hatch. The depth cards, one per 300 sq ft, show the settled depth mark, 16 to 17 in. for R-60 in cellulose, about 20 in. in blown fibreglass. Push a ruler down at the eaves over the top plate, where the roof pitch pinches the depth and where most “R-60” attics are R-20; the baffle must be in every rafter bay with the insulation stopped short of the soffit vent. The chimney dam, the pot light covers and the duct boots are photographed before the blow; if those photographs do not exist, that is the question.

The bag count is the arithmetic check that beats every ruler. The bag says how many bags per 1,000 sq ft reach a given R; multiply by your attic area and compare to the empties. 20% short on bags is 20% short on R, however deep it looks on the day it was fluffed. The attic inspection checklist goes through the before, during and after with what to photograph at each.

Spray foam, before the balance moves

1. The daily work sheet, filled in. Ambient and substrate temperature, lift thickness, the density cut, batch numbers, installer name and card number. CAN/ULC S705.2 requires it and the warranty depends on it. An unfilled sheet means an uninspected job.
2. Thickness with a pin. Push a wire coat hanger through the foam to the substrate at ten places per wall, more at the rim. 2 in. means 2 in. everywhere, not 2.5 in. in the middle of the bay and 1.25 in. at the studs where the gun tilted. You paid by the board foot; the pin is the invoice check.
3. Adhesion and shrinkage. Foam is stuck to the studs and the sheathing with no visible line along the stud face. A hairline gap at the stud edge on day one is a finger-width gap in two winters and the air seal is gone.
4. Colour, cells and smell. Closed cell is a uniform cream to yellow with a fine skin. Dark streaks, a crumbly or glassy patch, or a sweet or fishy smell three days later point to off-ratio foam, and the lift comes out.
5. The thermal barrier. Spray foam exposed inside a living space, which includes a basement, a finished attic and a garage with a room above it, gets 1/2 in. drywall or an intumescent coating at $1.25 to $2.00 a square foot before anyone lives behind it, OBC 9.10.17. An unfinished crawlspace or attic needs the lesser ignition barrier at $1.25. Bare foam in a living space is a code failure and a fire you can smell from the street.

What the building inspector checks, and what he does not

On a new house or a permitted renovation, the insulation and vapour barrier inspection is one of the scheduled Part 9 visits, between framing and drywall. The inspector looks for the R-value on the SB-12 form for each assembly, a sealed vapour barrier on the warm side, the attic baffles, the clearances at chimneys and vents, and that foam will get its thermal barrier. He is there for twenty minutes, he does not carry a pin, and he does not count bags. He does not come at all to a renovation with no permit, which is most attic top-ups.

So the inspector is a floor, not a ceiling. A house that passes can still have a gap along every top plate and an attic at R-45 billed as R-60. A blower door test after the job, $300 to $450 standalone, is the one instrument that checks the air barrier instead of looking at it, and on a house I have tightened I want the number before I pay; the blower door guide has the ACH50 targets by house age. A tightened house also needs its ventilation looked at, bath fans, HRV, and whatever burns fuel in the basement, before the heating season.

Questions people ask

Sources and further reading

• Ontario’s Building Code: the official page with the current regulation; vapour barriers are 9.25, attic ventilation 9.19, thermal barriers over foam 9.10.17, radon 9.13.
• CUFCA Quality Assurance Program: Canadian Urethane Foam Contractors Association: certified installers with photo ID, licensed contractors, daily work sheets and the CAN/ULC S705 standards a spray foam job is held to.
• Keeping the Heat In: Natural Resources Canada: the plain-language Canadian guide to air sealing, insulation materials, basements, walls and ventilation.