How to Repair Cracks in a Cement Board Ceiling
Cement board is a building material much like drywall in appearance. While drywall has a gypsum core, cement board has a cementitious core. Manufacturers make cement board by sandwiching cement between layers of fiberglass mesh. It has a smooth surface similar to drywall. Cement board holds up to damp conditions without soaking moisture in like drywall. Cement board is mold and mildew resistant, unlike drywall. It also has a higher fire resistance rating than drywall. Cement board is suitable for interior or exterior applications.
Things You Will Need
- Medium-grit sandpaper
- Latex modified mortar or joint compound with hydraulic cement
- Putty knife
- Fine-grit sandpaper
- Sanding block
Sand the cracks with medium-grit sandpaper to smooth the edges.
Apply latex-modified mortar, also known as thin set or use joint compound with hydraulic cement as an ingredient with a putty knife. Press the thin set or joint compound deep into the cracks. Extend the compound or thin set 1/4-inch past the crack on each side of the crack with a small trowel. Make the layer as thin as possible while covering the crack completely.
Allow the thin set or joint compound to dry fully, generally one to two hours.
Sand the repair surface with fine-grit sandpaper attached to a sanding block to level it with the existing ceiling.
Wear safety glasses and a dust mask while working on crack repairs. Allow the patch to dry for at least two hours before priming and painting.
Sal Marco began writing professionally in 2009. He has written many online home improvement articles based on his more than 20 years of experience in the home improvement and building industries. He has worked as both part of a team and as a site supervisor. Marco has a Bachelor of Science in management science from Kean University.