Penetrations, curbs, skylights and equipment · Lesson 4 of 4

Penetrations, curbs, skylights and equipment: defects, verification and case study

The defects that let water in at penetrations, a checklist that ties each check to its source, and two cases: a real skylight fall report and a hypothetical leak worked through the checklist.

You will be able to: Spot the common defects at a curb, pipe, pocket and skylight, check a finished detail against a source-labelled checklist, record the evidence with photographs, and explain the skylight fall in the Washington report.

9 min · 11 slides · 5 questions

All lessons in this module

Slide 1 of 11

Check: counterflashing matches the detail for the unit

IKO notes that nailing and metal counterflashing are not required if the membrane is up and over the curb before the unit is installed.

IKO’s rooftop-unit detail mounts its metal counterflashing tightly to the underside of the mechanical unit.

Check how the governing detail holds the counterflashing for your unit and roof system, and compare the finished work with that detail rather than assuming.

Sources

Detail T-CB-5 Termination at R.T.U. with counter flashing and separate flashing (issue date 8/01/2025) - IKO Commercial

Glossary

Backwater lap: A lap arranged so water can run into the joint instead of over it; MBCI says a welded cricket shingled into the roof prevents backwater laps.
Safety monitor and warning line: A fall-protection method for low-slope roof work that Washington’s fatality report says should not be used when unprotected skylights are present.
Mounded sealant: Pourable sealant in a pitch pocket built up in a mound so it does not pond water, as IKO’s detail requires.