Wood foundation house with vinyl siding. The hole that was made to allow the lines for my central air conditioner to enter the house is basically wide open - the silicone/caulking that was around the hole has eroded or something, and when I look at the hole from inside the house (in my furnace room) I can see clear through to the outside - I can see daylight. I was thinking of spraying some expanding foam into the hole, then using caulk to seal around the hole, but I'm wondering if that's the correct approach. Has anyone on here ever done this before?


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    Can you supply a picture or 3 of the area affected? – The Evil Greebo May 31 '16 at 13:25

Duct seal, or similar product, is a common solution.

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Kneed it until malleable, then mold it in and around the hole like clay. It is nontoxic, paintable, and will stay flexible.

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    @isherwood Please don't use expanding foam. It's a huge mess if the lines ever have to be removed, replaced, or inspected. – Tester101 May 31 '16 at 13:41
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    Duct seal is the way to go, and agree on avoiding expanding foam. Adding some fiberglass insulation to the inside may help with insulation and is easy enough to remove later. – BMitch May 31 '16 at 18:57

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