I found that one of my exterior doors are leaking cold air from beneath the door sill.

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The product installed is Endura Z-Articulating Cap Sill™ and Sealing System

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How can I seal it? Can I use silicone around the aluminum sill? Should I only seal from outside?

  • If you attempt to caulk it from the inside, you'll want to do a very nice job of it, since you'll see this caulk line. I'd suggest doing the outside first, then give it a while. If you need to, add a bead of caulk on the inside.
    – FreeMan
    Feb 11, 2021 at 12:49

1 Answer 1


It looks like the subfloor is concrete. you can use a silicone, urethane, or acrylic caulk.

If silicone be sure to get one that's suited to concrete and aluminium.

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