Flashing, Weeps, Ties & Movement Joints That Keep a Wall Dry

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Alright, Flashing, Weeps, Ties & Movement Joints That Keep a Wall Dry. Don't let the plain title fool you. Here's the part that actually matters on the job: A masonry wall is designed to get wet and drain, so install flashing the water can reach, weeps it can leave through, ties that hold the veneer without bridging the cavity, and movement joints the wall can breathe through. Learn it well and the wall you build stays dry and uncracked for decades instead of coming off in a repair.

The intro course gave the names and the spacings. This lesson is how each piece is installed so that it works.

Flashing that water can reach

Flashing goes where water collects: the base of the wall at the foundation ledge, under sills, over heads and lintels, at shelf angles, at roof-to-wall lines, and at the parapet. Stainless steel and copper last the life of the building. Flexible self-adhered membranes are easy to form but need a termination bar and a separate metal drip edge; asphalt felt fails inside a cavity. Whatever the material, the installation rules are the same.

• Shingle it. Flashing turns up the backup at least 8 inches and goes under the water-resistive barrier or into a reglet or bed joint of the backup, so water running down the backup runs onto the flashing, not behind it.
• Lap and seal. Laps are at least 6 inches and sealed with a compatible mastic or tape.
• Carry it out. Flashing extends to the face of the wall and is trimmed flush, or ends at a metal drip edge. Flashing stopped an inch behind the face drains water into the brick below.
• End dams. At sills, lintels, and anywhere the flashing stops, turn the ends up at least 2 inches to dam the water toward the weeps; preformed end dams make this reliable.
• Protect it. The course set on flexible flashing is laid in a full bed with care; a trowel edge cuts the membrane.

Weeps and a cavity that drains

Weeps sit in the head joints of the course directly on the flashing, never a course above it, no more than 33 inches apart; open head joints with a louvered insert are the most reliable. The cavity behind the brick is at least 1 inch and often 2 inches on commercial work, and it only works if it stays open: bevel the bed joint toward the cavity so the squeeze goes outward, cut mortar tags off the back of the brick, and set a mortar collection device at flashing level so droppings land above the weeps rather than on them.

Ties that hold and do not bridge

Veneer ties carry wind load between the brick and the backup and have to move vertically without transferring weight. On block backup and steel studs, use adjustable two-piece ties: the eye in the backup and the pintle in the brick bed joint, with the vertical offset between them limited to 1-1/4 inches under TMS 402. On wood frame with an air space of 1 inch or less, corrugated ties are permitted; they are fastened through the sheathing into the stud with a corrosion-resistant fastener, bent at 90 degrees within 1/2 inch of the fastener, and set in the bed joint, never bent up or down to reach a course. Ties are embedded at least 1-1/2 inches into the veneer bed with 5/8 inch of cover from the face. Spacing is one tie per 2.67 square feet, no more than 32 inches horizontally and 25 inches vertically for adjustable ties, plus ties within 12 inches of every opening wider than 16 inches, no more than 3 feet apart around it.

Control joints in block

A control joint is a deliberate, straight, vertical plane of weakness where shrinkage cracking is meant to happen. Build it as a true break: sash block or a plain end on each side, a preformed gasket or a shear key so the two panels stay in plane, no mortar across the joint, joint reinforcement stopped on each side, and a raked joint about 3/8 inch deep on the face, filled with backer rod and a sealant rated for the movement. Spacing follows the drawings; the common rule in industry guidance for an undesigned wall is 25 feet or 1.5 times the wall height, whichever is less. Joints go at changes in wall height or thickness, at pilasters and intersections, and at one jamb of a small opening and both jambs of a wide one.

Expansion joints in brick

Brick grows, so its joints are empty: a compressible filler or nothing at all, backer rod, and sealant with a bond breaker, never a rigid filler that cannot compress. Vertical expansion joints are commonly 20 to 30 feet apart on long walls, within about 10 feet of each side of a corner, at offsets and changes in height, and at parapets. Horizontal expansion joints go under every shelf angle so the brick below can grow upward without bearing on the angle: a soft joint of about 3/8 inch, kept open with a lipped brick or an exposed sealant joint. Ties and joint reinforcement do not cross an expansion joint; a flexible anchor can.

Going Deeper (Intermediate)

Sealant joints are built to a width-to-depth ratio of about 2 to 1, with backer rod sized a little larger than the joint, primed if the sealant manufacturer requires it, and tooled concave. A 1/4-inch sealant joint cannot absorb half an inch of movement. The mason's job is to keep the joints open, straight, and clean until the sealant trade arrives.

Advanced / Pro-Level

Pros read a wall for its water paths before they build it, then mock up the flashing at every change of condition, including inside and outside corners, on the sample panel. They insist that the water-resistive barrier and the window flashing on the backup are complete before the brick covers them, because the brick crew gets blamed for every leak that comes through them. They also coordinate the roof: through-wall flashing at the roof line and under the coping is where parapets fail.

Practice Challenge

On a brick veneer over block, the flashing at the window heads was laid on the lintel and stopped flush with the inside face of the brick, with no end dams and the weeps two courses up. What is wrong? (Answer: the flashing does not reach the face, so it drains into the brick below; it has no end dams, so water runs off the ends into the jambs; and the weeps are not on the flashing, so the water has no exit. Extend the flashing to the face or a drip edge, add end dams, and put the weeps in the course directly on the flashing.)

In Practice

A crew that flashes with end dams, keeps the cavity clean, and leaves every movement joint empty hands over a wall that drains in the first rain. A crew that shortcuts the flashing finds out two winters later, when the repair means taking the brick off.

Common Mistakes to Avoid

• Flashing stopped behind the face of the wall
• No end dams at sills and lintels
• Weeps a course or two above the flashing
• Corrugated ties bent up or down to reach a course
• Mortar or a rigid filler in a movement joint

Takeaway: A masonry wall is designed to get wet and drain, so install flashing the water can reach, weeps it can leave through, ties that hold the veneer without bridging the cavity, and movement joints the wall can breathe through.

Educational content only — not design, engineering, or hands-on instruction, and not a substitute for training under a qualified mason or the judgment of a licensed design professional. Follow TMS 402/602 and the building code as adopted in your jurisdiction, the project specifications, the manufacturer's instructions, OSHA 29 CFR 1926, and your employer's procedures for your work.