Architectural Flashing Supply
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Windows, doors and opening transitions · Lesson 4 of 4

Windows, doors and opening transitions: defects, verification and case study

Typical sill, head and jamb defects and why they fail, an inspection list to use before cladding covers the work, and a constructed case study traced to its cause and corrected.

You will be able to: Diagnose common opening-flashing defects from their symptoms, check an opening against a written list before it is covered, and explain the corrective steps for a constructed stained-window case.

9 min · 9 slides · 5 questions

All lessons in this module
Slide 1 of 9

Defects at the sill

BSC says a pan's function can be subverted if the collected water cannot drain to the exterior, for example when the window's bottom flange is sealed to the drainage plane.

DuPont says sill flashing must not slope to the interior.

A pan with no back dam or slope, or no end dams, lets water run to the interior or off the sides into the wall.

Correct and incorrect sill details, three pairsThree pairs with the correct detail on the left and the incorrect detail on the right. Row one: a sill pan with end dams holds water, a flat strip lets it run off the end. Row two: an open bottom flange lets the pan drain, a flange sealed solid traps water. Row three: a folded dog ear corner, and a cut corner closed only with sealant.Dams hold the waterNo dams: runs offABFlange open: drainsFlange sealed: trappedCDFolded dog earCut and sealedEF

Three pairs, correct on the left and incorrect on the right: a pan with end dams against a flat strip, an open bottom flange against one sealed solid, and a folded dog ear corner against a cut corner closed with sealant.

A
Pan with end dams: water stays on the pan
B
Flat strip with no end dams: water runs off the end
C
Bottom flange left open: the pan drains
D
Bottom flange sealed solid: the water is trapped
E
Flat folded dog ear at the pan corner
F
Corner cut and closed only with sealant
Row one is a front view, row two a side section and row three a view of the pan corner from above. Dashed arrows are the path of water.

Sources

Glossary

Subverted pan
A pan flashing whose function is defeated because the collected water cannot drain to the exterior, for instance when the window's bottom flange is sealed to the drainage plane.
Flat folded dog ear
A folded closure of a sheet metal pan's inside corner, which BSC says is much more durable than cutting the corner and sealing the seam.
Lateral water movement
Water running sideways along a flashing; end dams are needed to stop it running off the pan and into the wall.
Prepared opening
This module's term, not TN05's or BSC's: a rough opening with its WRB cut, pan flashing and any back dam in place and checked before the unit is set.