Preserving Old Brick Walls with Brick Sealant

What You'll Need
Rubber gloves
Safety glasses
Cleaning rags
Push broom
Brick sealant
Exterior paint
Oxygen bleach
Roller brush or paint sprayer

Bricks are a highly porous building material, and if you are experiencing leaks you may consider applying a brick sealant. To stop the leak, first try to cut off the water source. Then, clean the bricks and apply sealant. You can paint the bricks after you are done.

Step 1 – Cut off Water Source

Bricks are just clay that was fired in a kiln. Wind-driven rain can hit the exterior of your house hard enough to drive moisture through the bricks' pores. Water may also be leaking from roof gutters, plumbing fixtures, or air conditioner condensate drain lines. Bricks can absorb this water and transfer it to the frame or drywall of your building. Locate the source of the water and try to divert it from the bricks. Bricks that have been repeatedly soaked will exhibit efflorescence. This is an unsightly white or gray sediment of salts that is pushed out of the bricks by water pressure. If the moisture is weather-related proceed to clean the bricks and apply the sealant.

Step 2 – Measure and Purchase Materials

Measure the area of the brick wall or floor that you are preparing. Buy adequate cleaning solution and enough paint to coat the surface according to the manufacturer’s specifications. Choose whether you will use a clear brick sealant or colored paint.

Step 3 – Clean Bricks

Scrape large or sticky debris from the bricks with a putty knife before scrubbing them. Cleaning the bricks with a pressure washer is not recommended because it can damage the mortar joints. Instead, mix up a solution of oxygen bleach or washing soda. Pour or gently spray the cleaner on the bricks. Scrub the bricks thoroughly with the push broom or a brush, removing dirt and debris from the mortar joints and efflorescent residue from the brick surface. Allow the brick time to dry before applying the sealant. Inspect the mortar joints for signs of damage and repair them with sealant or caulk, if necessary. Be aware that not all types of silicon caulk are approved for use on masonry in freezing temperatures.

Step 4 – Seal Bricks

Apply several coats of the sealant with a brush or sprayer. Use a brush for small spaces or a sprayer for large walls. Choose a sealant specifically designed for masonry applications. The best kinds contain silanes or siloxanes. Sealants can give off harmful fumes, so use adequate ventilation or wear a respirator.

Step 5 – Paint Bricks

In some cases, you may decide to forgo the trouble of clear sealant and just prime and paint the bricks. Use latex primer and an exterior paint that is approved for coating masonry.