Attic insulation: still the best first move in most Canadian houses

In most older Canadian houses the attic is the single largest heat loss and the cheapest to fix. Twenty-five to thirty-five per cent of the heat leaving a typical pre-1980 detached house goes up through the ceiling, and unlike walls, the attic is accessible.

What it pays in 2026

Ontario's Home Renovation Savings pays $1,250 for attic insulation, within a total insulation envelope of up to $7,700 across attic, wall, foundation and exposed floor. Efficiency Manitoba pays per gigajoule saved rather than per measure, which suits attic work well because the savings are large. BC Hydro pays up to $5,500 for insulation across the measures.

The mistake that wastes it

Blowing insulation over an unsealed attic floor is the commonest error in Canadian retrofit and it is expensive twice: once because you paid for insulation that performs below its rating, and again because the moisture carried up by the air you did not seal condenses in the cold insulation.

Air seal first. Every penetration — plumbing stacks, wiring, the top plates of interior walls, the bathroom fan, the chimney chase, the attic hatch itself. Then insulate. An attic done in that order performs at its rating. An attic done in the other order is a repair job in ten years.

What the evaluation tells you that a quote will not

Whether the attic is actually your biggest loss. Sometimes it is not — a house with a well-insulated attic and an uninsulated basement will lose more below grade than above it, and the contractor at the door is not going to be the one to mention that.

In Ontario, insulation sits on the assessment path, so the evaluation is required anyway and $600 of it is covered.