Your attic insulation questions, answered plainly

How much does it cost to insulate my attic?

The price depends on the attic’s size, what’s already in it, and what has to be fixed before insulating. Isolation Cornerstone gives you a written price after a free visit. The details are on the attic insulation cost page.

Can’t you just give me a price over the phone?

Isolation Cornerstone could give you a per-square-foot number, the way it’s often done. Except vermiculite, mold or a blocked soffit don’t come through over the phone, and that’s exactly what moves the price.

If you come over, do I have to sign?

No. You keep the quote, even if you choose another contractor.

Do you work outside Montreal?

Yes. Isolation Cornerstone works in Montreal, Laval, Lanaudière, the Laurentides and Montérégie. Just next door to those areas? Call, and we’ll tell you right away. See the service area.

What’s the right R-value for an attic?

LogisVert asks for at least R‑50 over the whole roof surface. Isolation Cornerstone insulates to R‑51 minimum, and up to R‑60 when the attic’s height allows it.

Fiberglass or cellulose, which is better?

Both get blown into attics and both are common. Isolation Cornerstone works with blown-in fiberglass, which resists fire and mold. Whatever is already in your attic, we look at it during the visit.

Why not just add insulation on top of what I have?

Because if the ventilation is blocked, or there are air leaks or moisture, the new layer hides the problem instead of fixing it, and the damage keeps going underneath. Blowing more on top is often what gets done. We fix what’s wrong first, then we insulate. See attic insulation.

I get ice along the edge of the roof every winter. Is that related?

Often, yes. Warm air rising into the attic through leaks heats the roof, the snow melts, then freezes again at the edge. We seal the ceiling’s air leaks, install baffles at the soffits, then insulate. See attic ventilation.

I think I have vermiculite. What do I do?

Nothing, actually. Don’t move it and don’t go up to work in the attic: it can contain asbestos. Isolation Cornerstone removes it safely before insulating. See vermiculite removal.

There are black stains on the roof boards. Is it serious?

Black stains on the roof wood are worth a closer look by Isolation Cornerstone. On the roof deck, they are usually mold, and it comes from moisture trapped under the roof: blocked ventilation, air leaks, a bathroom fan blowing into the attic.

If you clean up the mold, will it come back?

Not if the cause is fixed at the same time. That’s why Isolation Cornerstone decontaminates the roof deck and corrects the ventilation and air leaks in the same project. See attic mold removal.

Do I qualify for the LogisVert rebate?

The basic conditions: a house, not a condo or a multiplex, heated mainly by electricity, at an address that has never received this measure. Take the four-question check; the decision is Hydro-Québec’s.

Why caulking on top of the insulation?

Hydro-Québec requires both jobs to pay the rebate. The caulking covers windows and doors, but also the attic hatch, the range hood, bathroom fans, outlets and the fireplace, and Isolation Cornerstone does it in the same project as the insulation. See the LogisVert rebate.

How long does the work take?

The timeline depends on the attic, especially if it has to be decontaminated or cleared of vermiculite first. Isolation Cornerstone writes it in your quote.

Do I have to empty the attic, or be home?

Isolation Cornerstone explains what to prepare at the visit. On the day of the work, the house is protected with tarps and shoe covers, and we clean up at the end.