Getting ready to repair the chimney crown, using this Family Handyman article as a guide.

On our chimney, there is a line of bricks around the crown that have exposed holes in them. The holes are facing upward, and I imagine that they could potentially allow rain to seep in.

Should those holes be covered/plugged at all? Potentially with the chimney crown sealer?

Border of bricks with upward-facing holes

2 Answers 2


Those holes should be filled with at least with masonry cement. You can get it at the big box stores, it is sold in 60lb bags for a few bucks. It does not matter whether it is fast set, type S, it just needs to be masonry cement. No need to mix the whole bag. A 5 gal bucket to mix it in and a Tupperware(r) container or large coffee can will hold about what you need. Get a margin trowel, also at the same store you get the cement. Mix it to a peanut butter consistency and carefully place it around the edge of holes. With a little coaxing it should go in. DO PROTECT the roof, it will stain it, or keep a garden hose on the roof with you. You will need something to keep the roof clean from the chimney crown material.

Do not let the material you use to protect the roof be the same material that throws you off the roof. Stepping on a loose tarp will do it fast. Plywood acts like a skateboard. Be careful!

The way the chimney crown material works, you may only need it to get hard overnight before you apply the chimney crown material


I am in the midst of resetting some chimney stones with mortar and re-crowning. Your crown cement looks a bit cracked and tattered. You might consider removing anything that is loose and topping your crown with new sand mix with acrylic binder added for adhesion to the old surface. Put it on thicker rather than thinner to prevent future cracking. Also, I would cover those brick holes with a beveled surface of sand mix so the water tends to roll off the edge of the brick rather than pooling. I plan to use concrete sealer as well after my crown has dried to minimize water absorption on the surfaces.

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