Spray foam insulation

[joxafa]

Does anyone have it in their attic? I've been told it's great on the electric bill. Also been told it causes mold and moisture problems. One ac guy told me not to use it because the ac unit wouldn't run efficiently. Another told me he's never had a problem. I'm not sure which way to go. Thanks

 

[100percent]

Tagging

 

[displacedtexan]

I have open cell in my shop. I love it.

Not the same situation, but throwing it out there.

 

[grfox92]

You don't spray foam attics. You loose fill blow in with Celluslose or even better and not crazy expensive is wool blown in.

Spray foam walls and loose fill in the attic. FWIW I build custom homes for a living.

Edit: I'm not saying you can't spray foam your attic, it's just not something I've ever seen done. The cost wouldn't justify it. You don't live in your attic and unless your really dead set on using the entire thing for storage, blown in loose fill would be way less than half the coast of foam

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[goodgrouper]

New construction or existing? Blow in is so cheap you can just addd more to what you already have and gain efficiency. The mold problems come when you don’t have adequate ventilation. We do spray lids in applications where there’s no way to ventilate.

 

[Sled]

You got good advice here. Fwiw, I wouldn't put spray foam in the attic or anywhere moisture could be present.

 

[Broomd]

I have open-cell Icynene sprayed in my Idaho home and can practically heat this place with a candle.
No attic, we have a loft. As was said, blown-in for attic, 'expanding' for everything else.

Best build decision I ever made. My home-building neighbors built accordingly after seeing the ultra efficiency here.

 

[SwiftShot]

Spray foam and moisture happen when you have hot cold sides. You get condensation building like in a tent. This typically happens with I think less than 2 inches of foam. There is an R value but I do not remember it. This will be based on your temps. Ie in Montana will be different than Florida. In shops I understand spray foam but retreo fit an attic I would use traditional. If you are building like I am a Barndominium, well foam makes sense as there is no attic.

 

[Swampcruiser]

Spray foam in the attic is risky unless the System is built for it- venting. Better off with loose cellulose blown in and a vented deck.

 

[elkguide]

Living in a colder climate, working construction and seeing the growing use of spray foam, it has a lot of plusses and a few negatives. As has been said, it does seal things up tight and it certainly makes heat retention excellent. If you spray your roof in the rafters, many shingle manufacturers automatically void any warranty. I watched a house that was fully spray foamed add an air exchange unit as the house was so tight and the homeowners felt that they and their children had all developed allergies and were sick a lot after a winter inside. The plus side for them was that they had heated a 3200 square foot home on just over a cord of wood during a colder than normal winter. If you have to move/add a wire after you have used spray foam it is a real nightmare. After saying that, when my daughter builds this summer, I'll be using spray foam in the walls and dense pack in the rafters.

 

[Wrench]

One of my friends built a post and beam type home. They did spray in. The day after it was obvious. You can heat the house with the heat from the refrigerator. Pretty incredible.