Sealing an Indoor Chimney

by David
(Seven Fields, PA)

Question: I have an indoor brick and mortar chimney that goes from the floor to the cathedral ceiling in my great room. Mortar continually drops a fine dust or sand on the mantel. I thought applying a sealer would prevent this from occurring. Am I correct and what type of sealer would I use?

Dave's Answer: I’ve experienced good luck with grout sealer. Clean the bricks and allow them to dry. Spray with grout sealer and again allow the bricks to dry. I would use a flat finish unless you want some sheen. If you do want some sheen, use a satin finish. The added benefit of the sealer is that it will reduce the amount of smoke that gets in the bricks.

Is the chimney moving? There should be no reason for mortar to be falling out. Are there any cracks? If so, you may have a bigger problem.