How to Fix Water Leaks Through a Brick Wall

When properly built, a brick-and-mortar wall will hold off the worst of weather. If there are flaws in the wall, though, water can easily leak through, damaging any wall covering on the interior, and raising the humidity enough inside a structure to cause rotting to wood and fabric alike. The most common cause of leaking is the separation of the bricks from the mortar. Fortunately, for minor separation issues, do-it-yourself repair is possible by sealing the interior brick surface. Though it won’t close the cracks, it will keep the water at bay for as long as the seal holds, typically up to two years.

Damp patches around mortar edges are an indication of a leaky brick wall.

Step 01

Remove any paint from the interior of the brick wall by brushing a moderate layer of paint remover over the brick surface.  Wait 10 minutes for the remover to penetrate the paint, then scrape the remover and paint away with a putty knife. Wipe paint from any hard to reach crevices in the wall with a piece of cloth. 

Step 11

Scrub the wall clean of any residue with a scrub brush and a pH-neutral cleaner.  Use a concrete degreaser on any portion of the wall with an oil stain present. Rinse the cleaner from the wall with water, then pat the brick surface dry. 

Step 21

Search the wall for any visible cracks in the mortar.  Fill the cracks with joint repair compound. Use a putty knife to pack the cracks to the surface of the mortar, then smooth the compound out.  Allow the compound to dry overnight.

Step 31

Fill a hand-held pump sprayer with brick and masonry sealer.  Pump the handle of the sprayer three or four times to increase the internal air pressure. Point the nozzle of the sprayer at the wall, then cover the wall with a moderate coating of the sealant, stopping just short of saturating the surface with the liquid. 

Step 41

Roll the sealant evenly over the bricks with a low-nap paint roller.  Roll the wall twice, once in a back-and-forth motion running the length of the wall, then in an up-and-down motion, covering the wall height. Allow the sealant to dry overnight, then apply a second time, following the same coverage methods. 


  • Wear a face mask and safety goggles when using the sealer to avoid eye contact and inhalation of the sealer fumes.
  • Open any doors or windows to the room to increase room ventilation.

About the Author

Larry Simmons is a freelance writer and expert in the fusion of computer technology and business. He has a B.S. in economics, an M.S. in information systems, an M.S. in communications technology, as well as significant work towards an M.B.A. in finance. He's published several hundred articles with Demand Studios.