Cementitious waterproofing is a cement-based coating, mixed with polymers and applied like a thick paint or slurry, that bonds to concrete or masonry to block water penetration.
Understanding Cementitious Waterproofing
Cementitious waterproofing is mixed on site or supplied pre-blended, then applied with a brush, roller, or trowel in one or more coats directly onto concrete or masonry. As it cures, it forms a rigid, water-blocking layer that becomes chemically bonded to the substrate rather than just sitting on top of it like a sheet membrane.
What Affects How Well It Performs?
Substrate preparation is critical, since the coating needs a clean, sound, and properly profiled surface to bond correctly. Application thickness and the number of coats also matter, as most systems require at least two coats applied in different directions to eliminate pinholes and ensure full coverage. Because the finished coating is rigid, structures that move or crack significantly can cause the waterproofing to crack along with them.
Cementitious Waterproofing vs. Sheet Membrane Waterproofing
A sheet membrane is a manufactured roll product, often rubberized asphalt or PVC, that is adhered or mechanically fastened to a surface. Cementitious waterproofing is liquid or slurry applied and cures in place, which makes it easier to apply around pipe penetrations, corners, and irregular shapes where sheet goods are harder to install cleanly.
Practical Tips for Cementitious Waterproofing Applications
Pre-wet the substrate as the manufacturer recommends before applying, since a dry, thirsty surface can pull water out of the mix too fast and weaken the bond. Apply in thin, even coats rather than one thick coat, since a single heavy application is more prone to cracking and pinholes. Allow full cure time before backfilling or exposing the area to standing water, since an undercured coating can fail under hydrostatic pressure.
Also Called
Cementitious Coating, Cement-Based Waterproofing
