Leaking Brick Walls

Many people believe that brick walls are waterproof.  This couldn’t be further from the truth.  Water leaks through brick walls through various avenues including:

  • through the porous brick itself
  • through the porous mortar joints that bind the brick together
  • Cracks in the brick and the mortar joints.
  • Around windows and terminations.

After a day of rain, particularly wind-driven rain, these avenues can contribute to substantial water leakage through a wall.  And even when the brick wall appears to be in good condition, a significant amount of water will pass through the mortar joints and brick itself because these materials are actually porous.  Sometimes the worst thing that can happen is that the  leaks do not move through the entire wall and into the interior living space. When this happens, leaking water remains hidden inside the wall assembly and this can lead to substantial damage to the wall including mold, wood rot and often structural damage.

In order to waterproof a brick wall, all avenues of moisture intrusion must be addressed.  First off, any cracks or holes should be repointed to ensure there are no voids which will allow a large quantity of water through the wall. If the joints between the bricks are in generally poor condition, sometimes it is necessary to repoint the entire brick wall. Making sure that the brick wall joints are in good condition is just the first step to waterproofing a brick wall, however.  Even if the joints are in a good condition, water will still be absorbed into the wall. In order to prevent this from happening it is important to apply a clear waterproofing material to the brick. This waterproofing material will clog the microscopic pores in the brick and morar and will cause water to bead off a brick wall.  The best product to prevent water absorption through brick is a 100% silane material. Unlike silicone waterproofing from years ago, silane penetrates the brick and creates a waterproof barrier.    Because silane penetrates the brick, it doesn’t easily breakdown overtime from UV light like silicone does and can last well over 25 years.

At this point it is important to make sure the caulking around windows, penetrations, and joints is in good condition.  Caulking has a limited life expectancy so caulk should be replaced when possible.

Last but not least,  base flashing should be installed at the bottom of brick walls.  This is actually a building code requirement that is often overlooked.  Base flashing is installed by removing brick at the bottom of the wall or just above a window. Flashing is then installed which will direct any water that accumulates behind the wall out the wall through weep holes.

So to recap, in order to waterproof a brick wall it’s important to make sure there are no open cracks and voids in the masonry. Then a clear silane waterproofing should be applied to the brick wall to prevent the brick from absorbing water. Windows and penetrations should be properly caulked and sealed.  Lastly, base flashing should be installed to direct any water that does get through the brick out the wall assembly.

  1. Spot pointing or pointing of the entire brick wall
  2. Clear silane waterproofing
  3. Window caulking. Seal around all penetrations
  4. Base Flashing

Performing some the steps above will certainly reduce leaking of bricks and could possibly eliminate leaks entirely.  Taking all of the steps above will waterproof a brick wall.