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Troubleshooting Brick Veneer

Start with the roof flashings

Troubleshooting Brick Veneer

Start with the roof flashings

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    Moisture often collects in the cavities, sheathing, and framing behind brick veneer. The owners of the home pictured here tried to have the problems that resulted in recurring leaks and damage to  pricey custom finishes inside repaired many times. But “repairs” that consist of applying tubes of caulk or mastic around windows and flashings are inevitably a waste of time. Getting to the root of this house’s problem was a little more involved than that.

  • Figure 1. Counterflashings installed in saw-cut kerfs, whether at shed roofs (A) or sloped roofs (B, C), do nothing to divert water from the cavity behind the brick. These installations have a high rate of failure; copious amounts of caulk and the presence of nails or screws are dead give-aways that the flashing is useless. The sketch above, made by the author during a site visit, explains to the client the difference between a kerfed-in and a through-wall flashing.

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    Figure 1. Counterflashings installed in saw-cut kerfs, whether at shed roofs (A) or sloped roofs (B, C), do nothing to divert water from the cavity behind the brick. These installations have a high rate of failure; copious amounts of caulk and the presence of nails or screws are dead give-aways that the flashing is useless. The sketch above, made by the author during a site visit, explains to the client the difference between a kerfed-in and a through-wall flashing.

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    Counterflashings installed in saw-cut kerfs--such as this one above a shed roof--do nothing to divert water from the cavity behind the brick. These installations have a high rate of failure; copious amounts of caulk and the presence of nails or screws are dead give-aways that the flashing is useless.
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    A counterflashing let in to a saw kerf above the joint between a roof rake and house wall is unlikely to prevent moisture from seeping into veneer brick and the cavity and framing behind it.
  • Figure 2. Stepped counterflashings installed in mortar joints (above) are no better than saw-cut flashings at diverting water from the cavity  unless they happen to run through to the sheathing and tuck under the building paper, which is rare. The work often gets sloppier where the installer thinks no one will see it, as in this bungled mishmash of surface-applied metal (right).

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    Figure 2. Stepped counterflashings installed in mortar joints (above) are no better than saw-cut flashings at diverting water from the cavity unless they happen to run through to the sheathing and tuck under the building paper, which is rare. The work often gets sloppier where the installer thinks no one will see it, as in this bungled mishmash of surface-applied metal (right).

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    Stepped counterflashings installed in mortar joints are no better than saw-cut flashings at diverting water from the cavity — unless they happen to run through to the sheathing and tuck under the building paper, which is rare.
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    A mishmash such as this is an indication that the stepflashing doesn't go through the wall and has proved ineffective. The surface-applied metal flashing above the roof peak won't help at all.
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    A properly flashed sidewall requires through-the-wall pans with soldered end dams.

  • Figure 3. A properly flashed sidewall uses through-wall pans with soldered end dams (A, B), installed in stepped fashion as the brick is laid. Once the through-wall flashings are mortared into place (C), the roofer will install step flashings, followed by copper counterflashings that are secured to the through-wall hems with pop rivets. Note the wasp screens on the weep joints.

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    Figure 3. A properly flashed sidewall uses through-wall pans with soldered end dams (A, B), installed in stepped fashion as the brick is laid. Once the through-wall flashings are mortared into place (C), the roofer will install step flashings, followed by copper counterflashings that are secured to the through-wall hems with pop rivets. Note the wasp screens on the weep joints.

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    The pans are installed in stepped fashion as the brick is being laid with the bottom of the pan set on top of a brick course and the back leg fastened against the sheathing. Building paper or housewrap should be lapped over the back leg of the pan. Mortar is placed in the bottom of the pan to lay up the next course of brick.

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    Once the through-wall flashings are mortared into place, the roofer will install step flashings, followed by copper counterflashings that are secured to the through-wall hems with pop rivets. Note the wasp screens on the weep joints.
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    MCA

    For good measure, we also added a layer of uncured rubber membrane over the flashing laps. . . .

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    . . . and at the ends of the flashing. It’s been years now and they’ve not had any leaks since.

Brick has been used in residential construction for centuries, and it’s not hard to understand why. It’s simple, attractive, and durable. Yet it’s also associated with some of the most troublesome repair jobs I see in my work as a consulting forensic architect in Nashville, Tenn.

In this article, I’ll focus on standard residential brick veneer — that is, nonstructural brick installed as a cladding over wood framing — and share examples of some of the failures I’ve inspected. Sadly, I see the same mistakes made again and again — mistakes that often result in very expensive callbacks.

Take the house whose repairs we cover in the slideshows. The owners reported recurring leaks and damage to pricey custom finishes inside. By the time I was called in, they were understandably upset at the many failed attempts to fix the problem. Typically in a case like this, the “repair” consists of applying tubes of caulk or mastic around windows and flashings — inevitably a waste of time. As you can see from the photo, getting to the root of this house’s problem was a little more involved than that.

So how can a material so durable go so wrong? Simple: It doesn’t. As with any building material, successful installation depends on workmanship and details — rarely does the brick itself fail. Laying up a flat wall with straight, even courses and raking the mortar joints is the easy part; the challenge is making sure that the brick is supported properly, that it’s securely tied to the structural wall sheathing, and that adequate measures have been taken to ensure that moisture that gets behind the brick can exit to the outside.

Where Does the Water Come From?

Brick is made from clay and fired at high temperatures. Naturally, that makes it water-resistant, right? Generally, yes — especially modern brick. (Older bricks are more porous, and will absorb a surprising amount of water.) But that doesn’t mean a brick veneer wall is waterproof. One culprit is the joints. Mortar is made by mixing water, sand, and cement. That alone introduces tiny air bubbles. And once it’s troweled on and the water in the mix evaporates, you have even more holes, as well as lots of hairline cracks that form between bricks. Wind-driven rain will soak the wall, and as the moisture moves from wet to dry and warmer to cooler, the back of the brick will eventually get wet — you can count on it.

Plus there are all the other common leak spots — like roof and wall penetrations, and (of course) windows.