Architectural Flashing Supply
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Water control and drainage continuity · Lesson 4 of 4

Water control and drainage continuity: defects, verification and case study

Defects that break water control continuity, the checklist and photographs that document it before concealment, and a constructed lintel case worked step by step against code and publisher values.

You will be able to: Recognize the common continuity defects at openings, wall bases, weeps and roof-wall joints, document evidence before the wall is covered, and work a constructed lintel case from defects to a sourced target condition.

11 min · 9 slides · 9 questions

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Slide 1 of 9

Defects at openings and lintels

Without end dams, water a flashing collects at a lintel can run off its ends and into the wall.

IMI asks whether end dams are at or beyond the end of veneer lintels.

BSD-013 says leaks often occur at lapped joints of rigid flashing, and that these should be sealed, not just lapped.

BIA Technical Note 7 says to lap continuous flashing at least 6 in and seal with compatible sealant or adhesive.

Correct against incorrect lintel flashingTwo elevations of a steel lintel. Correct: flashing extends past the lintel with turned-up end dams, a 6 inch sealed lap, weeps above at the specified spacing and a drip projecting beyond the face. Incorrect: flashing cut flush with no end dams, a short unsealed lap, weeps far apart or blocked, the flashing stopping short of the wall face with no drip, and the flashing sagging. Letters P, Q, S, T and R sit beside the defect they name.Lintel flashing, right and wrongElevation of a steel lintel over an openingEnd dams, 1 in minLaps 6 in, sealedWeeps per specDrip beyond faceCorrectPQSTPCut flush, no damsQShort lap, unsealedSWeeps far apartTFlashing sagsRIncorrect

Two elevations of a steel lintel. Correct: flashing past the lintel with turned-up end dams, a 6 inch sealed lap, weeps above and a drip beyond the face. Incorrect: flashing cut flush with no end dams, a short unsealed lap, weeps far apart or blocked, the flashing stopping short of the wall face with no drip, and the flashing sagging.

P
Flashing cut flush, with no end dams: water runs off the ends into the wall
Q
Short, unsealed lap between pieces
R
Flashing stops short of the wall face with no drip, so water can wick back under it
S
Weeps far apart or blocked with mortar
T
Flashing sagging because it is not supported
Correct against incorrect, schematic and not to scale. The 1 in end dam and 6 in lap are BIA; the small boxes show the edge at the wall face in section: the correct drip extends past the face, while the incorrect flashing stops short of it with no drip (BIA recommends extending flashing beyond the face).

Sources

Videos for this lesson

What this video shows: An International Masonry Institute clip. Its description says shorter pieces of flashing that end in the wall return vertically as end dams, and describes an end dam as a flashing pan.

Video: A.08A Flashing end dams by International Masonry Institute, on YouTube. Chosen from the video's published description.

What this video shows: An International Masonry Institute clip. Its description says drip edges are often projected 1/4 in to 1/2 in from the veneer face, and that a flush flashing detail is acceptable only if it is truly flush, not recessed or held back from the face.

Video: A.21 Flashing drip edge - Hemmed & flush by International Masonry Institute, on YouTube. Chosen from the video's published description.

What this video shows: An International Masonry Institute clip on a low roof meeting a high wall. Its description says the masonry flashing is connected to yet independent of the roof flashing, and that the roof ties in at a sheet metal receiver.

Video: A.31 Roof to wall detail by International Masonry Institute, on YouTube. Chosen from the video's published description.

Glossary

Reverse lap
A lap that lets water run into the joint instead of over it, because the lower piece covers the upper one. The AFS rule is that the upper piece always laps over the lower one.
Face-sealed wall
A wall that tries to stop all water at one outer plane. BSD-013 says such perfect barriers often fail to perform as designed.
Drainage media
A plastic mesh or fabric in the air space that lets water pass and catches mortar droppings at the wall base.