Electrical Box - How and what to seal with


Old 10-30-17, 01:01 AM
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Electrical Box - How and what to seal with

I was walking through some new home constructions today and saw that they used spray foam to insulate make the electrical box air tight. I really want to do the same think to my outer wall electrical boxes. I have a couple questions I was hoping someone could help me with:

(1) I was thinking about just using a silicone caulk (like a GE Silicone II* door/windows) around the edge of the box and the drywall. This would make putting the plate back on a lot easier. Would this be a good product for this? Is this smart, would a home inspector come in and be like no?

(2) There is defiantly a hole in top of the box where they run the wires in. I do not want to fill the box with spray foam, just the hole. Is there a special kind of spray foam I should be using? Is this smart, would a home inspector come in and be like no? The air would still vent thru the duplex socket (no worthless foam pad behind face plate).

(3) Could I use the GE Silicone II* for caulking the 3/8 inch hole they ran thru the dry wall? This would be the 3/8 inch holes for like a lighting fixture in a bathroom.

I have been searching the internet everywhere and I give up. Someone please help.

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Old 10-30-17, 06:00 AM
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You don't say if you are currently building or planning for a future build. There are boxes already made with a gasket material added for the purpose you describe.

If spray in insulation is used you will already be sealed around the boxes.

A home inspector has no enforcement powers.

Old 10-30-17, 09:02 AM
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Do not use silicone caulk. Instead, use a siliconized acrylic latex caulk. The difference is that the latex caulk can be cleaned up with water before it hardens AND it can be painted. Straight silicone caulk cannot be painted.
Old 10-30-17, 09:38 AM
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Thanks for the caulk idea. I wasnt too worried about paint, but it will make it better.

Anyone know if it is a good idea to spray foam the electric box hole with wires running through it? and this is a 30 year old home ..... Any guidance here?
Old 10-30-17, 10:49 AM
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Caulking or spray foaming around boxes is a great idea and can certainly reduce drafts. Don't go overboard - you'll be saving some money in heating, but it's not a cure-all. In a 30-year old home, there should already be decent insulation in the walls, but back then, they didn't often do a great job with a vapor barrier and full sealing as you've probably noticed. So the foam or caulk will help seal those cracks.

And A+ to Furd's comment about using latex or siliconized latex caulk.
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