Protecting Your Homes Brick. Brick veneer is a porous material which exposed to a constant source of moisture will absorb it. Both air and water can penetrate brick veneer. Moisture can do a great amount of damage to your homes brick, typically by spalling finish. Both brick and concrete are vulnerable to moisture, and can degrade, or “spall,” over time, especially when subject to freezing/thawing cycles.
Bricks for residential homes may be made from clay, shale, soft slate, calcium silicate, concrete, or shaped from quarried stone. However, true bricks are oven fired, and therefore created by the action of heat and cooling. Clay is the most common material, with modern clay bricks formed in one of three processes – soft mud, dry press, or extruded. Cement brick are the hardiest of brick finishes and have the same consistency as your foundation masonry block.
As a Professional Home Inspector in Barrie ON, I come across many brick homes where the brick weeping holes have been filled, commonly with spray foam or caulking, this is not permitted as the weeping holes are very important for drainage and air circulation for space behind brick. These weep holes are required to be spaced 600 mm apart or 24 inches by Part 9 of the Ontario Building Code. Plastic or metal preformed weep holes screens can be utilized to keep our insects etc.
Poor workmanship is one of the main causes of brick failure. The rate of water absorption is probably the most important factor concerning workmanship. Knowing the correct mixture for the ambient temperature also affects the bonding of mortar and brick. The results will affect how “rain proof” the wall is. In areas where moisture can not be avoided it is recommended that you treat your exposed brick with a water proofing solution. These are clear and do not change appearance of brick. A little preventive maintenance can save a huge expense later.
When not constructed properly with flashing and weep holes at the bottom of the brick wall, the trapped moisture may cause wood framing to decay and mold to grow. The weeping holes allow collected moisture and water to drain. The weeping holes also provide entry for air movement allowing moisture and heat to escape. Solar heat from the sun will drive moisture on surface of bricks through into the cavity adding to moisture content.
Most window sills, whether concrete or brick, are susceptible to moisture damage during the freezing thawing cycles of winter. Solar heat will drive moisture on surface of bricks through into the cavity adding to moisture content.
The Barrie Home Inspector routinely comes across this problem at the early stages of mortar cracking and routinely points out to his clients the benefits of maintenance in preventing more severe damage. The old adage of “an ounce of prevention is better than a pound of cure” is especially true in the maintenance of your brick window sills.
by Roger Frost