Why the Attic Is Always First

Three reasons, in order of importance

1. Heat goes up

Warm air rises, collects at the ceiling, finds every gap in it, and leaves. In a pre-1990 Ontario house the ceiling plane and the air leaks through it account for more loss than any other part of the envelope, and usually more than the walls and windows combined.

2. It is the cheapest surface in the house to treat

An attic is an open floor you can walk on, reachable through a hatch, with no finishes to remove and nothing to make good afterwards. A wall needs drilling, plugging and patching. A basement needs framing. A window needs replacing. The attic just needs somebody to go up there with a hose.

3. It is the only one you can claim on its own

The programme designers ranked the measures the same way we just did. That is why the attic is the one measure with a stream of its own that requires no energy assessment: up to $1,250, one visit, no advisor in the house. Everything else needs the slower pathway and two measures minimum.

The ranking, for the whole envelope

1. Air sealing the ceiling plane. Cheapest of all, and normally bundled with the attic job rather than sold separately.
2. Attic insulation to R–50. The big one.
3. Rim joist. Small area, disproportionate leak, rarely looked at.
4. Exterior walls, where there is a cavity to fill.
5. Exposed floor over a garage, if there is a cold room above it.
6. Basement walls.
7. Windows and doors, last, and for reasons other than energy.

The exception

If your attic already measures over R–35, none of this applies to you and adding more depth is a poor use of money. What is often still worth doing on a deep attic is the air sealing and the ventilation, because a deep attic with blocked soffits and a bare hatch performs like a shallow one. We will tell you that rather than sell you inches you do not need.

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