Windows, doors and opening transitions · Lesson 3 of 4

Windows, doors and opening transitions: methods and worked application

The installation sequence from pan flashing to head flashing, which sealant and tape rules belong to which product, metal pan and storefront details, and four worked examples with every input labelled.

You will be able to: Follow the crew sequence for a flanged window with the WRB on, apply the lap and sealant rules, and work out head piece, jamb flashing and sill pan lengths from labelled example inputs while recording assumptions and units.

15 min · 12 slides · 10 questions

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Slide 1 of 12

The crew sequence

The TechNote's sequence for a flanged window with the WRB on. Read the maker's instructions first; DuPont wants the rough sill level or sloped out.

Prepare the WRB: cut, fold in at jambs, fold up at head
Install the pan flashing
Set the window to the maker's instructions
Install the jamb flashing
Install the head flashing (TN05 step 5)
Fold the flap down and tape the diagonals

1: Prepare the WRB at the opening
2: Install the pan flashing
3: Set the window to the maker's instructions
4: Install the jamb flashing
5: Install the head flashing (TN05 step 5): over and beyond the jamb flashing, and over the drip cap if installed
6: Fold the WRB flap down and tape the diagonal seams

Steps 1 to 6 are the 2015 builder TechNote's own numbered steps (flanged window installed after house wrap). TN05 step 5 says the head flashing goes over and beyond the jamb flashing, and over the drip cap if installed; it says self-adhesive flashing is common for jamb and head flashing. The pan flashing is outlined in red where AFS's metal sill pan is used. Rules from DuPont, Pella or BSC are on the following slides, not in this order. Always read the product maker's instructions first.

Sources

TechNote: Window and Door Flashing - Code Requirements and Best Practices (September 2015; quotes the 2015 IRC section R703.4), as hosted by the Town of Ocean City, Maryland - TechNotes builder series
DuPont Flashing Products Installation Guidelines: Integral Flanged Window with Wood Bump-Out Frame (43-D100978, March 2021) - DuPont (copy hosted by EMI Supply)

Glossary

House wrap flap: The flap of water-resistive barrier cut at the head of an opening, folded up while the pan, window and flashing go in, then folded down at the end of the TechNote's sequence.
Nail fin (mounting flange): The flange around a flanged window that is fastened to the wall; makers say not to tape or seal the bottom one so the sill can drain.
Dog ear: A flat folded corner in a sheet metal pan where the end dam meets the back dam, used instead of cutting the corner and sealing the seam.
Splice sleeve: A joining piece under the joint between two lengths of storefront sill flashing; the maker calls for a splice joint between members and sealant over it.
Developed length: The flat length of a formed piece before folding; in AFS's method a sill pan equals the opening width plus extensions plus the two end dam upturns.