Cement plaster is a good plaster to use to coat a cement block wall. The major benefit of cement plaster is that it creates a beautiful appearance and provides consistency for blocks that may be out of alignment. The structure of a block wall enables cement plaster to coat effortlessly due to its solidarity. Cement plaster can be applied to the block walls or over lath.
Step 1 - Check Your Cement Wall
Make sure to check if the concrete wall has been painted before. If the paint is cracked you will want to remove all of the paint. If there is an issue regarding the bond of paint you must apply lath. If the concrete wall is waterproofed, you must secure the lath to the wall before applying plaster. If caulking is required, do this before applying the first coat of plaster.
Step 2 - Testing the Blocks
Test the cement blocks to check for water durability. If the cement blocks absorb water easily, the plaster should bond well to the blocks. If water is not absorbed well, secure a lath.
Step 3 - Dash Bond Coat
Apply a dash bond coat to the cement blocks. The coat should consist of portland cement mixed with 1 part fine sand and water. The coat should be 1/8 of an inch thick. Let dry.
Step 4 - Apply Cement Plaster
Apply the cement plaster 3/8 of an inch thick.
Step 5 - Apply a Brown Coat
Apply a brown coat and let it cure for 7 days. Apply the finish coat. Putting cement plaster on block walls helps protect against water and deflects rain.