Attic insulation--which type?

Mon, Mar 20 2023, 1:12 pm

I've gotten a few quotes for attic insulation--large walk up attic with very high pitched ceilings. Some companies recommend fiberglass, which I think is in rolls, and some recommend blown in soft cell. Pricing from various companies is all over the map. Any ideas on what work best in terms of cooling/heating, safety, etc? If I want to someday finish the attic, I'll need to put drywall over it, not sure if one is easier than the other for that purpose?

cookier

Mon, Mar 20 2023, 2:41 pm

jf wrote:

Not sure what blown-in soft cell would be. Was it a recycled paper product? If so that would be cellulose, otherwise it could mean spray foam?

The main types of insulation are fiberglass batting, blown-in fiberglass, blown-in cellulose, and spray-in foam which can be open cell or closed cell.

Fiberglass batting is better off inside walls, but it’s not great in open attics. Its R-value (insulation value) is typically higher than blown-in fiberglass though.

Blown-in fiberglass and Cellulose are pretty on-par, I think cellulose typically has a better R-value than fiberglass. Cellulose is typically treated with fire retardants and both can be treated with pesticides. Cellulose is a cheaper. But, if you’re serious about making it a living space, both are going to require cleanup and replacement when you do that.

Spray foam is by far the best, but also the most expensive. It would be sprayed on the inside of the roof (sheathing) and in between the joists, which make up the ceiling of the room below. Because it adheres to the sheathing, it would be easy to cover up if/when you decide to finish the attic. Your contractor could likely just come in and trim it flat and install drywall over it. Spray foam comes in closed cell and open cell. Closed cell has a typical R-value of 6.5 per inch and 3.6 per inch, so it’s the gold standard of efficiency. It does require off-gassing though, so you’d want to talk to your contractor about the safety of being in the home during application. If you can afford the cost upfront, and live somewhere cold or very warm, you’ll see savings long term, and probably pretty noticeable savings over removing and replacing if you finish the attic.