Brick Weep Holes at the Roof Line Should Stay Open

Many brick houses in St. Charles County were built as brick veneer over a wood frame, and many of them have a roof that runs into a brick wall somewhere along the side or back. At that junction, the brick does not stop water. It slows it. Behind the brick there is an air space and a layer of flashing, and whatever soaks through the face is supposed to run down that flashing and leave the wall through small openings called weep holes. Those openings are usually open head joints or short plastic tubes set into the mortar. They are easy to miss and easy to fill, and a roof job is one of the moments when they get filled.

What a weep hole does

A weep hole is a drain, not a vent and not a decorative gap. It sits low in the wall, typically at the bottom course of the brick veneer and above any flashing that spans an opening such as a window or door head. When water gets into the air space behind the brick, gravity moves it down until it meets the flashing, and the flashing carries it to the weep hole. The flashing should slope outward so that water runs toward the hole rather than back toward the wall. If the hole is clear, the water drains out onto the surface below. If the hole is full of mortar, caulk, paint, or insulation foam, the water has nowhere to go and it stays in the wall.

Freeze and thaw matter here. A wet air space in a St. Louis winter freezes and expands, and repeated cycles push on the mortar joints and the brick faces. A blocked weep hole does not cause the freeze on its own, but it keeps the air space wet for longer, which means more cycles of ice and thaw in the same place. Over a few seasons that shows up as spalled brick faces, loose mortar, and efflorescence, the white salt that appears on brick when water moves through it and evaporates at the surface.

Where a roof meets the brick

The spots that matter on a roof job are the places where a lower roof, a porch, a dormer cheek, or a sidewall meets the brick. At those points there is usually step flashing or counterflashing set into the mortar joint, and there may be weep holes or a flashing line sitting just above the roof surface. A porch roof running into a brick wall is the most common example in older St. Charles County houses. The porch roof drains onto its own surface, and the wall above it drains through openings that discharge close to where the shingles are.

That is why the roofer and the mason, if you have one, need to agree on the wall before anyone seals anything. A roofer who cuts the mortar joint to tuck new counterflashing can disturb the joint that holds the weep hole in place. A crew that caulks the roof-to-wall line by habit can seal the bottom of the joint shut. Neither of those is a roofing problem in the narrow sense, and neither will show on the day of the tear-off. They show a season or two later as a stain on the brick or a wet spot on the ceiling below the wall.

What to ask the roofer before the crew arrives

Ask each roofer to show, in writing, where the crew will touch brick. A useful scope names the brick, the mortar joints, the flashing, and the weep holes separately, rather than lumping them into a line that says flashing as needed. If the quote includes new counterflashing into a brick joint, ask whether the crew will cut the joint, whether they will repoint it, and what the mortar will be. Repointing with a hard, high-cement mortar on older soft brick can trap moisture and crack the brick, so the mortar choice is a real question, not a detail.

Ask also whether the crew will leave the weep holes open and check them after the work. That is a fair request and a simple one. The roofer should be able to say where they are on your house, which ones sit above the new roof surface, and what they will do to keep them clear. If the answer is that the crew does not work on brick, ask who does, and get that name on the same page as the roof scope.

Before the tear-off, walk the wall with a phone

You can do a quick check yourself before anyone quotes the job. Stand back from the wall at the roof line and look at the bottom course of brick and the joints just above any lower roof or porch. A flashlight helps in the shadow under an eave. Look for small openings, or for plastic tubes that look like short drinking straws. If you see a joint that is solid mortar where a hole ought to be, note it. You do not need to dig anything out. Take a photo, date it, and keep it with the roof file.

Also look for the signs of a wet wall. White powder on the face of the brick, flaking mortar at the base of the wall, a dark band where the brick meets a lower roof, or a stain on the ceiling directly inside the wall. Any of those tells you the water is already getting in somewhere, and the roof quote should say what the crew will do about the wall, not just the shingles.

What the roof job should leave behind

When the job is finished, the wall should look as open as it did before, with the weep holes still clear and the flashing still doing its work. Keys documents the condition of the wall with photos and measurements, and puts a written scope with those photos in your hands, so the state of the brick is on paper before anyone moves a ladder. If you want the crew to look at the brick at the roof line before you sign anything, call Keys at (314) 220-2333 and ask for the wall to be part of the walk. That request is much easier to settle before the first shingle comes off than after the first winter.