Finishing a roof, the crew forgot the 3-inch vent boot until after all the shingles were on.

No, it is not properly sealed. This is a code violation and a leak waiting to happen.

Code Violations (IRC R905.2.8.2 / IBC 1507.2.9):

1. Flashing Placement: The boot flange must be interlaced with the shingles—top and sides under the upslope shingles, bottom over the downslope shingles. Setting the flange entirely on top of finished shingles violates the "shingle fashion" lapping principle required for all roof flashings.
2. Fastener Sealing: Nails driven through the flange on top of shingles penetrate the weather surface with only silicone for protection. Code requires fasteners to be covered by the next course of shingles.
3. Silicone Reliance: Silicone/caulk is not an approved primary flashing sealant for roof penetrations. It fails due to UV, thermal cycling, and adhesion loss. IRC R905.2.8.5 requires flashing to be "installed in accordance with the manufacturer’s instructions"—no major boot manufacturer approves surface-mounting on finished shingles with caulk.

Why it will leak:

• Water running down the roof hits the vertical flange wall, pools, and finds the nail holes or the silicone bond line.
• Wind-driven rain pushes water under the bottom flange edge (which sits on granular shingle surface, not flat deck).
• Neoprene boots shrink/crack; silicone separates from granules.

The Fix: Strip shingles back around the pipe (approx. 2 ft radius). Install a proper retrofit boot (e.g., Oatey Master Flash, Dektite) with a flexible aluminum base that slides under the upslope shingles and over the downslope shingles. Re-shingle the area. If the pipe height prevents sliding a standard boot down, use a split-boot designed for retrofit (mechanical clamp + sealant under the flange, not on top).

Bottom line: Foreman is wrong. This requires tear-off and re-flash. Do not sign off.

No, this installation is not code-compliant or reliably sealed.

The correct method for a roof vent boot (pipe flashing) requires the *flange to be installed under the shingles*, not on top. Specifically:

• The bottom edge of the flange must lap under the course of shingles below the pipe.
• The sides and top of the flange should be covered by shingles (or sealed with roofing cement if not feasible), ensuring water flows over the flashing, not behind it.
• Nailing through the flange into the roof deck is acceptable, but only if the flange is properly positioned to shed water.

By placing the flange on top of the shingles and nailing through it, you’ve created a dam that traps water behind the flashing. Even with silicone sealant, this is a temporary fix at best. Silicone degrades under UV exposure and thermal cycling, and it’s not a substitute for proper shingle lapping per IRC R905.2.8.1 (asphalt shingle flashing requirements) and manufacturer instructions.

Neoprene boots are designed to seal around the pipe, but the flange must integrate with the shingle layer to shed water. Installing it on top invites leaks, especially during wind-driven rain or ice backup.

Action: Remove the shingles around the pipe, install the boot correctly (flange under shingles, sides/top covered), and re-shingle. Seal the pipe collar with roofing cement or the boot’s integrated seal. Do not rely on surface-applied silicone as the primary water barrier.

If the crew cannot redo this properly, consult a licensed roofer — improper flashing is a leading cause of roof leaks.