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Brick is one of the most popular exterior materials for houses. It's beautiful, and people associate it with a solid, well-made structure. But you have to be careful.

Most people think a brick house is solid, but really the brick is just a veneer - not much different than siding or stucco. Brick facades are not connected directly to the wood interior walls; there is a space between the inner and outer walls to allow air to flow.

The brick is laid against a stick-framed and wrapped structure. And that's where a lot of the problems I see with these houses come up: between the brick and the structure.

Even though it's strong and solid, brick is porous and absorbs moisture. With rain driving against a brick wall, it will take only about two hours for the water to soak through. If the wood framing and sheathing behind the brick get wet, they can rot or develop mould.

A properly made brick wall has small gaps in the mortar joints along the bottom course to allow any water that gets in behind to escape. There should be a similar series of gaps at the top of the wall to allow air to get in. If those holes aren't there, the water that gets in won't have anywhere to go. It could end up passing through the wall and into your house - to the drywall and interior.

Benefits of brick

This building material is durable, long-lasting, as well as fire- and impact-resistant. And because of its mass and the air pocket, it also acts as a natural sound barrier.

Brick is made of densely packed clay and has a high thermal mass, which slows down heat transfer - it absorbs and loses heat slowly. It takes up to eight hours for 15 degrees to be transferred from the exterior brick face to the surface of an inside wall, compared with only one hour for exterior wood cladding.

The most common bricks in use today are made of clay. The colour of clay provides a natural beauty that doesn't fade over time. (Many new-home builders opt for cement brick, which is denser and costs less than clay, but it doesn't look the same.)

The pros know how

As in every other area of contracting, the quality of the work depends on who's doing the job. Make sure you hire guys with skill and experience, who love what they do.

If you are doing a renovation or repair, ensure that your contractor has more than enough bricks from the same batch to complete the job, since colour and texture can vary between production runs.

The brick also should come from the same manufacturer: Common red clay bricks may seem all the same, but they vary depending on who's making them. . Mortar matters

Not only does a bricklayer have to use the right mortar mix, with the right consistency, he has to make sure the bricks are connected properly with the most efficient mortar joint. That would be a concave (also called a recess or raked) joint, which curves inward and allows water to run off, preventing pooling on the inside edges of the bricks.

It seems to be the style these days to scrape out about a quarter of an inch of mortar and leave it flat between rows of brick. Some people think this looks nice, but it creates a huge problem by reducing the lifespan of brick by as much as 25 per cent.

What happens is water sits on top of the exposed edge, allowing moisture to seep into the brick. The moisture will freeze in the winter and damage the surface, then the whole brick.


Brick is low-maintenance. It doesn't need painting or sealing or replacing every 20 years. But older brickwork can spall - flake and break down. It that happens, you could have a big job on your hands.

When bricks get wet and freeze, the expansion causes the harder outside fired surface to break off. This exposes the softer inner part of the brick, which is more porous and holds water better. The bricks will quickly crumble, and have to be replaced - they can't be repaired. You'll need an experienced, licensed masonry contractor to do this.

Mike Holmes is the host of Holmes on Homes on HGTV.

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