Why Broken Arrow brick homes leak at the slab line

What a weep hole is actually doing

Brick and mortar absorb water. In a driving rain from the southwest, the kind that comes across Broken Arrow in May, a brick wall can take on gallons. Behind the brick there is an air gap of an inch or so, then the sheathing and house wrap on the wood frame. Water that gets through the brick runs down the inside face of the veneer, and at the bottom it needs a flashing to turn it back out and a gap to exit through.

The gap is the weep hole. On a house built to current code it is an open head joint, a small tube, or a rope wick at the base course and above every window and door. The Brick Industry Association technical notes on water penetration have described this drainage wall system for decades, and the residential code has required weep holes at a maximum spacing of 33 inches since the early 2000s.

Why so many houses here have none

Broken Arrow and the south Tulsa suburbs bricked tens of thousands of houses between 1975 and 2000, and the trade practice at the time was to set the first course tight to the slab with no flashing and no gaps. Masons were paid by the brick, inspectors were not looking for it, and the houses looked fine for twenty years. Then the clay under the slab did its work, joints opened, and the water that had always been getting in started arriving faster than the wall could dry.

On houses built after about 2005 the weep holes are usually there, and the problem is that somebody closed them. Painters caulk them, pest control companies foam them to keep insects out, and owners fill them thinking they are a defect. A closed weep hole is the same as none.

What it looks like from the outside

You can check your own house in five minutes. Look at the bottom two courses on the north and west walls after a rain.

• A dark band across the bottom courses that stays wet a day after the rest of the wall has dried
• White efflorescence bloom on the base course and nowhere else
• Mortar in the bottom joints that crumbles when you press it with a screwdriver
• No open vertical joints anywhere along the base course, or joints filled with caulk or foam
• Interior drywall or baseboard that is soft or stained on the outside walls

How the retrofit is done

A weep hole and flashing retrofit is done from the outside without touching the interior.

1. Hose test the wall to confirm water is collecting at the base rather than entering at a window or a crack higher up.
2. Cut out the first course of brick in sections of four to six feet, leaving the courses above supported.
3. Clean the mortar droppings out of the cavity, which is usually packed solid at the bottom on older houses.
4. Install a through wall flashing that laps up the sheathing and out over the slab edge with a drip.
5. Relay the first course with open head joints every 24 inches, then repoint to match.
6. Seal the elevation with a breathable silane and siloxane repellent once the mortar has cured.

What it costs and what moves the price

A retrofit runs $1,500 to $6,000 per house. A single story ranch where only two walls hold water sits at the low end; a two story house with all four elevations in clay and mortar packed cavities sits at the top. The full table is on the cost page. What you should not do is pay for sealer first. Sealing a wall that is wet from behind holds the water in, and the brick spalls within a couple of winters.