Should I Finish or Seal a Cement Fireplace Cap?

Learn which products keep a chimney cap sealed and watertight – and which to avoid.

LESLIE: John, you’ve got The Money Pit. How can we help you today?

JOHN: I’m working on a cement fireplace cap on top of my fireplace. What I’m needing to find out is what kind of paint or some kind of sealant I can use to keep my cement fireplace cap from being weathered so fast.

TOM: Well, generally, you don’t use a finish on that at all. You could use a masonry sealer. If you do, make sure you get one that’s vapor-permeable, because that means that the moisture can evaporate out of it, doesn’t get trapped underneath and then freeze and sort of crack. But most importantly, you want to make sure that that cement cap is pitched properly so it’ll go from the clay liner, out to the edge of the brick. And if you make it so it’s a bit thick at the edge, it’ll be a little bit more durable as that – because that’s the edge that will typically chip off and break off the quickest. Does that make sense?

JOHN: OK. Well, I thank you very much for your advice.

TOM: Good luck, John. Thanks so much for calling us at 888-MONEY-PIT.