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nathanincanada 10-04-2012 05:47 PM

Spray foam in attic space.
I am currently renovating a mud room, powder room and small hallway connecting the 2 rooms. Because of mice and water issues around an exterior door I am removing all the insulation of the exterior walls and from the ceiling. I was planning on using spay foam for the exterior walls and possible between the joists in the ceiling. But we are planning to put recess lighting and/of pot lights. Now is there a way yo use spray foam with the pot lights? Is there anything I need to do to prep? Or do I just spray right over it as the electrical is self contained in the box?

Windows on Wash 10-05-2012 07:03 AM

There are insulation contact rated can lights as well as air tight can lights.

I would still recommend creating a drywall box around them prior to spray foaming.

Is the ceiling between floors? If so, you don't need insulation between the floors.

No need to use spray foam as the primary insulation in this case as it is a bit expensive for that purpose. Use rigid board, 1-part foam, and batt insulation (or a combination of all 3).

nathanincanada 10-19-2012 05:08 AM

It is an attic and I'm trying to make it air tight by insulating it with spray foam since we have had mice problem in the past. Also that attic crawl space shares the attic with my garage unheated. ( which is how the mice get in). If I use air tight pot lights with boxes do I spray right over them or would the heat from them being on cause issues with the foam?

Squished 10-19-2012 06:18 AM

Spray foam right around the IC rated lights. They wouldn't be rated "insulation contact" if you couldn't insulate around them. Creating a box around them would create nothing put the perfect opportunity for an air leak.

Windows on Wash 10-19-2012 08:16 AM

You can very easily box out around the light fixtures and then seal that box (usually fire rated drywall or sheet metal) right down to the attic floor with spray foam. There is no difference in air tightness if done properly and some IC rated fixtures will trip the overload switch if the are covered in SPF because it does such a good job of keeping in the heat. Boxing them out will prevent this.

You can spray to the IC can light but if somebody is overly aggressive, you can get foam into the light fixture and it does not allow you to ever service or change out the fixture in the future.

Boxing them out and sealing down the box does give you that flexibility in the future and be sure to mark out there locations with marker flags so that nobody steps on them in the attic if you blow loose insulation after the fact.

Squished 10-19-2012 08:34 AM

If you go as far as using fire rated drywall and/or sheet metal, yes you can air seal it successfully. Getting foam into the fixture is a whole nother story....bad stuff I'm sure can happen there.

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