Architectural Flashing Supply
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Through-wall flashing, end dams and weeps · Lesson 4 of 4

Through-wall flashing, end dams and weeps: defects, verification and case study

Missing and misplaced end dams, flashing stopped behind the face, unsealed laps, punctures, weeps in the wrong place or clogged, a pre-cover inspection card, photographs of hidden work, and a constructed case of a stained window head.

You will be able to: Recognise eight through-wall flashing defects, tie each to a published rule, check the work before it is covered, record it, and reason from a symptom to a likely cause.

10 min · 11 slides · 7 questions

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Slide 1 of 11

Eight defects to look for

Each of these is tied to a published rule on the slides that follow.

  • No end dam where the flashing stops
  • A dam that stops inside the lintel end
  • Flashing stopped behind the face
  • Short or unsealed laps
  • Punctures at anchors and bolts
  • Weeps a course above the flashing
  • Weeps clogged, or tube weeps
  • Galvanized or aluminum in the mortar
Four correct and incorrect details side by sideFour rows, correct on the left with a green check and incorrect on the right with a red cross. 1: an end dam turned up on a head flashing, against a flashing cut square with water running off its end. 2: dams beyond the ends of a lintel, against dams stopping inside the lintel ends. 3: flashing past the face with a drip, against flashing stopped behind the face with water wicking down the brick. 4: a weep in the first course immediately above the flashing, against a weep one course higher with water ponding on the flashing.Dam turned up 1 inNo end dam1Dam beyond lintel endDam inside lintel end2Past the face, dripStopped behind face3Weep at the flashingWeep a course up4

Four rows, correct on the left with a green check and incorrect on the right with an amber border and cross. 1: an end dam turned up on a head flashing, against a flashing cut square with water running off its end. 2: dams beyond the ends of a lintel, against dams stopping inside the lintel ends. 3: flashing past the face with a drip, against flashing stopped behind the face with water wicking down the brick. 4: a weep in the first course immediately above the flashing, against a weep one course higher with water ponding on the flashing.

1
An end dam turned up where the flashing stops, against no dam
2
Dams at or beyond the lintel ends, against dams inside them
3
Flashing to and past the face with a drip, against flashing stopped behind the face
4
Weeps immediately above the flashing, against weeps a course higher
Each pair is one published rule: BIA on end dams and on weeps and the face, IMI on dams at or beyond the lintel ends. Water is teal, a teal hatch is water ponded on the flashing, flashing is red, incorrect panels are amber-bordered, not to scale.

Sources

Glossary

Mortar bridging
Mortar or other protrusions that span the air space. BIA says bridging, and mortar droppings that clog the weeps, can let water reach the interior.
Weep rope (wick)
A rope placed through the head joint as a weep. BIA does not prefer it: if used, wicks are at least 16 in long and at no more than 16 in on center. IMI notes rope wicks do not let air into the cavity.
Open head joint
A weep formed by leaving the mortar out of a head joint. BIA prefers it, at least 2 in high and at no more than 24 in on center.