How to Seal Concrete Blocks

Concrete block is a building material that is most often used for home construction and for building walls. Even though it is made of a strong, durable material, it is also porous. This means that it is capable of absorbing moisture which can lead to mold, cracking and other damage. The method you should use to seal them depends on whether they are inside or outside. Both methods are moderately simple to accomplish.

You will need:

• Latex block filler


• Paint pan and roller


• 6-inch masonry brush


• 5-gallon bucket


• Cement-based foundation coating


• Electric drill with mixing paddle attachment

Interior 

1. Use a masonry brush to remove dirt and debris from the surface of the block.


2. Pour the latex sealer into a paint pan carefully. Stir the latex only if it is indicated on the packaging.


3. Use a paint roller to apply a coat of sealer to the surface of the block. Make sure to coat any deep pits. Repeat on other cement blocks, if needed.


4. Allow the latex to dry as long as the packaging indicates.

Exterior

1. Use a masonry brush to clear away any dirt and debris from the surface of the block.


2. Pour the foundation coating into a 5-gallon bucket and mix it with a drill and paddle attachment.


3. Use a masonry brush to apply a thick coat of foundation coating to the block.


4. Repeat on other blocks as needed.


5. Allow the coating to dry completely.