How to Find a Water Leak in a Brick Wall

Of all the wall materials you might have thought were the most impervious, brick would be at the top of the list. Can it really be that brick can leak water? Unfortunately, it happens all the time.

Masonry Magazine mentions that your home may have one of two possible types of brick wall systems. The first is a barrier-type and the second is a drainage-type. The latter is the more common type of wall.

To build a drainage-type wall, the wall is supposed to have sized weep holes, flashing, and open air space throughout. The weep holes are especially important in the construction of the walls, as the holes send water out if it reaches the masonry.

In an adequately designed and well-built drainage wall, there should be no concerns about water leaks. However, as Masonry Magazine notes, sometimes the wrong joints for a brick wall get chosen, which invites the possibility of water leaks.

Even if the team selects the right type of joints, under-mixing or over-mixing the mortar can impact joint strength and functionality, as can failing to correctly measure the mortar ingredient quantities. If the joints aren’t quite filled in all the way, leaks are also likely.

Mortar issues allow leaks to occur in two ways: in the space between the mortar and the brick or through the mortar itself. Bricks too can be the source of the leak, as they’re considered porous. 

According to news resource The Globe and Mail, in about two hours of being pelted by rain, a brick wall can become completely soaked. The moisture can pass through the brick and affect whatever’s behind it. Perhaps this is wood framing. If so, the wood will rot, becoming structurally unsound. Mold and mildew will also develop, further hurting the structural integrity of your home.

The water-resistant qualities of the brick wall can be increased through what’s known as tooling. During tooling, the construction team will flatten the mortar. This pushes more mortar to the joints and makes the mortar smooth throughout the brick wall. In doing so, the surface of the joint and the mortar are more level. This results in fewer crevices, so water can’t as easily get in.

Okay, so you’re feeling especially nervous after having read all that since your brick walls have sprung a leak. The question is, where exactly is the leak occurring?



You have a few methods that work on brick walls for finding leaks, as outlined in the intro.

By far, the most surefire method in your arsenal is to do the spray test as shown in this YouTube video by Mark Meshulam. It’s ideal if you can locate the opposite side of the brick wall if you want to see quick results, but by misting or spraying the brick wall directly, the areas that are leaking should become apparent.

To do so, Meshulam uses a spray rack, which is like a multi-hosed apparatus. You might not have access to such a tool, but lightly spraying your wall with a garden hose ought to produce the same effect.

Depending on the level of masonry damage, it can take 20 seconds or longer for a leak to appear, so keep at it for a little while. As the water begins traveling down the brick wall, let it move naturally, then later, study its trajectory. Follow the water stain all the way to its source, then take a closer look at that source on both the inside and outside of the brick wall.

Brick naturally comes in all sorts of colors, everything from black to brown, red, pink, buff orange, tan, and cream. Therefore, unless you know what your brick wall looks like pretty well, this next suggestion might not work.

Remember, brick is quite porous. As brick absorbs water, its color can change. That particular brick may look much darker than the surrounding bricks. Sometimes a water-soaked brick takes on a splotchy appearance as well.



Brick porosity can vary, which means that the amount of water the brick is absorbing is also flexible. An area of brick wall that’s leaking likely has so much water that the excess has to go somewhere. Thus, that affected area may be discolored.

Your last option is to do a mold and mildew check. Admittedly, you’re much more likely to see mold and mildew on the inside of the masonry wall than the outside, given the variables when it comes to the porosity of brick. If your brick is very porous, that means it retains water, the moisture of which will attract bacteria. Less porous brick might not.

The wood and other materials on the other side of the brick wall will get very moldy though, especially wood. It would take some seriously leaky conditions for the mold or mildew that starts on the inside of the masonry wall to reach the brick itself, but it’s not impossible.

Now that you’ve found the offending area(s) of your brick wall that’s leaking, how do you go about fixing it?

Before you get to that point, it’s a good idea to call a water damage restoration professional. They can visit your home to determine the full extent of the damage. 

Although the water leak may have started from your brick wall, depending on the severity of the leak, other areas of your home may have water damage as well. Your restoration team will check such parts of your home as the trim, baseboards, insulation, cabinetry, subflooring, main flooring, and drywall to ensure these haven’t become rotted from the brick wall leaks.

You can also rely on these professionals for repairing the damage. For very minor leaks, a bit of caulk along the mortar might be able to stop water from coming through. Barring that, new mortar might be applied. In the most serious cases, the brick could have to be taken out with fresh, less porous brick installed in its place.

Masonry Magazine notes that fixing a leaking brick wall is not necessarily a one-and-done process. If you’re not 100 percent sure where the leak is emanating from, or if another unmitigated leak appears, repairing the issue is all about time, patience, and seeing what works versus what doesn’t.

Brick walls can leak due to poor construction, not mixing mortar correctly, or failing to fill in the wall joints with mortar. Pinpointing the source of the leak is best left to a spray test for accurate results.



Now that you know how to find brick wall leaks, you can get your masonry repaired before water damage wrecks the rest of your home!

• https://www.masonrymagazine.com/blog/2016/04/25/leaky-walls-brick-buildings/
• https://www.theglobeandmail.com/life/home-and-garden/a-brick-house-isnt-as-solid-as-you-think/article571941/
• https://www.youtube.com/watch?v=hWvPBQa9r4c