OK to spray foam over ceiling fan mount/bracket in attic?
MaineGuy80
| Posted in Energy Efficiency and Durability on
We have 3 ceiling fans on the second floor. We used those brackets that turn into the joists for support and then there’s a box that the electrical and fan mount to. I’ve caulked between the sheetrock and that box, however, I’d like to foam over it. Is that safe and OK to do? I’m going to do the same for the smoke detector boxes.
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Replies
Yes.
I’d put some foil tape over the holes in the box before foaming it. The purpose of the tape is to prevent the spray foam from oozing into the box and expanding in there, which WILL happen a little if you leave the holes open. It’s not enough to fill the box, but it’s a nuisance and technically a code issue with box fill. I use the foil tape because it stays stuck reliably during foam application, but it’s not the only tape that will work. Just be careful because the chemicals in the foam seem to cause some kinds of adhesives to release.
Once you have those holes covered it’s not a problem to apply spray foam over the box and associated wiring. You might want to make sure the fasteners are all right first though since the foam will make it impossible to do anything to them later.
Bill
Hi, Fasteners for what part? I will foil tape the boxes- good idea and some may already be set with the caulking but I'll double check it.
I'm not sure if this matters, but if it does, help me to understand. Looking at the specifications for the two products, Loctite is not recommended for attics/ceilings but Great Stuff is.
https://www.lowes.com/pd/LOCTITE-TITE-FOAM-Multi-Purpose-12-oz-Spray-Foam-Insulation/1000881630
https://www.lowes.com/pd/GREAT-STUFF-SMART-DISPENSER-Gaps-and-Cracks-12-oz-Spray-Foam-Insulation/1000673769
Those boxes with the spanner bracket to go between joists usually have a screw clamp that secures the box to the bracket. Just make sure that’s tight before you apply spray foam. You might also check that the bracket is securely fastened to the joists too. Just think “is there anything I need to do while I can get to it, because once I apply spray foam, everything will be inaccessible”.
Bill
The "specifications" tab on the Lowes page is not really accurate. Both products will work for what you are talking about. I haven't use the version of Great Stuff you link to. The loctite foam I have used has been nice to work with.
The pricing I see from Lowes seems expensive vs. Home depot: https://www.homedepot.com/s/great%2520stuff?NCNI-5