How to Paint an Indoor Concrete Block Fireplace

Lay a plastic tarp down on the floor surrounding the fireplace. Rub a wire brush over the fireplace, scraping off any old paint or dusty surfaces. While wearing gloves and goggles, clean the concrete with TSP and a scrub brush. Rinse the concrete with fresh water and let dry completely.

Cover any holes, chips or damaged areas on the concrete with concrete patch. Apply the patch with a trowel and smooth the trowel across the top. After the patch dries, rub fine-grit sandpaper over the concrete until it sits flush with the fireplace.

Apply a thin layer of concrete sealant to the fireplace, using a paintbrush. The sealant blocks the surface of the concrete and keeps rain or moisture from moving through the concrete and causing peeling of the paint or primer.

Paint the primer on top of the sealant with a paint roller. Once the primer dries, go back over the fireplace with a paintbrush, reaching any areas you missed with the roller, including in between the blocks. The primer reduces the amount of paint needed on the fireplace.

Coat the fireplace with an even layer of paint applied with a paint roller. As you did with the primer, use a paintbrush and fill in the hard-to-reach areas. After the first coat dries, apply additional coats until the paint reaches the desired color.