How to Coordinate a Penetration with the Trade That Owns the Assembly
Why this matters
Most of the holes a service shop cuts go through something another trade built and still stands behind: a roof under a manufacturer's system warranty, a rated wall in a building whose general contractor (GC) holds the firestop schedule, an EIFS wall an applicator repaired last year, a sealed crawlspace an encapsulation company guarantees. Cut it without a call and you can void the owner's warranty on that area, inherit the next leak, and find yourself in the middle of an argument between the homeowner and a company you have never met. The call takes ten minutes. The point of it is to leave with four answers: who cuts, who seals, who inspects and who warranties.
Step 1: Name the assembly and find who owns it
Before you schedule anything, write down what you will penetrate and who has a stake in it:
| Assembly | Usual owner of the work | Why they care |
|---|---|---|
| Roof covering | The installing roofer, and the shingle or membrane maker if a system warranty was registered | Many system warranties condition coverage on how later penetrations are made |
| Rated wall or floor in multifamily | The GC during construction; the building owner or association after | Their firestop systems and inspections are on record |
| EIFS or stucco | The applicator or a repair contractor | A repair warranty may exclude damage from new penetrations |
| Sealed crawlspace | The encapsulation contractor | Their liner and moisture guarantee |
| New construction anything | The GC | They sequence trades and hold the permit |
Why first: the owner is not always obvious, and on a house a few years old the homeowner may not know who did the roof. Ask for the paperwork; a registered roof warranty usually names the installer.
Step 2: Read the clause that governs penetrations
Ask the homeowner or building manager for the warranty or the association's rules and find the section on alterations, penetrations or work by others. Typical shapes: penetrations must be made by the original contractor or a certified one, the maker must be notified, or the area around an unapproved penetration is excluded. Note what it actually says rather than assuming.
What that clause means for the owner's coverage, and whether your work affects it, is a contract question for the owner and their own attorney or the warranty provider. This is not legal advice. Your job is to read it, tell the owner what it says, and act inside it.
Step 3: Call before the cut, with specifics
Have the facts ready: what the penetration is for, its size, where it lands (a photo of the spot helps), the material you plan to use, and your target date. A vague "we need to put a vent through the roof" invites a vague answer.
TECH: Hi, this is Dana with the HVAC shop. You did
the roof at 418 Linden about three years ago?
ROOFER: Sounds right. What's going on?
TECH: We're adding a bath fan. It needs a 4 inch
vent through the north slope, about six feet
up from the eave. Homeowner says there's a
registered warranty on the roof.
ROOFER: There is. If we don't flash it, they lose
coverage around it. We'll cut and flash.
TECH: Good. Who cuts the deck, you or us?
ROOFER: We do the deck, boot and shingles. You set
the duct to the boot from the attic.
TECH: And sealing the duct at the deck is ours?
ROOFER: Yours. Inspection's the homeowner's permit,
right?
TECH: Ours, we pulled it. I'll put this in an
email today. Monday morning work for you?
ROOFER: Monday after nine.
Why it works: each of the four questions got an owner, out loud, before anyone touched the roof. The tech asked rather than assumed who cuts the deck, which is where two trades most often each think the other one did it.
Step 4: Settle the four answers and the record
Whatever the assembly, these four come out of the call:
- Who cuts. Deck, sheathing, gypsum, foam, liner. One name.
- Who seals or flashes. The weather, fire, air or moisture layer the cut went through. One name per layer if the work splits, as it does when the roofer flashes the boot and the HVAC tech seals the duct to the deck from inside.
- Who inspects. The building official under whose permit the work falls, the association's inspector, or the warranty maker's representative. Somebody signs off.
- Who warranties. Which party stands behind which part from today. "Roofer for the flashing and shingles, us for the duct and its connection" is an answer; "we'll figure it out" is not.
Add a fifth line that is not optional: who keeps the record, meaning the photographs of the cut before it is closed. See related: The Penetration Record SOP.
Step 5: Put it in writing the same day
Send a short message to the other trade and copy the owner: date, address, penetration, the four answers, and the schedule. Ask the other trade to reply to confirm. If they do not reply, call once more and note the call.
What breaks if skipped: six months from now, nobody remembers who said what on a phone call, and the email is the only version either of you can point to.
When the owner of the assembly cannot be reached or will not come. Roofers go out of business, and some will not schedule a small boot for months. Do not quietly cut it anyway. Give the homeowner the choice in writing: wait, have another contractor the warranty maker accepts do the flashing, or proceed with your shop flashing it with the roof maker's own components and its instructions, knowing what the warranty clause says. The decision is the owner's, and the record shows they made it.
Step 6: Sequence the work and cover the gap
Plan which trade goes first and what happens to the house in between. On the bath fan job the HVAC crew mounts the fan and runs the duct to a point below the roof deck on Thursday, caps the duct, and leaves the roof untouched until the roofer arrives Monday. Nobody cuts a hole in a roof and covers it with a tarp for four days to save a trip.
Hazard: the attic work happens on Thursday, so it carries attic hazards then: step only on framing or a walk board laid across it, keep off insulation that may hide the ceiling below, and work in the morning in hot weather with a second person aware (see related: How to Move Through an Attic Without Stepping Through a Ceiling). The roof work is the roofer's, and the HVAC tech has no reason to be on the slope. If a tech does go up, fall protection follows the activity: 29 CFR 1926.501 at 6 ft for construction work, 29 CFR 1910.28 at 4 ft for general-industry maintenance.
Step 7: Do your part, photograph it, and hand it off
Do exactly the part you agreed to, and photograph the cut and the layer you were responsible for before it is covered. On the bath fan, that means a photo of the duct sealed to the boot collar and the deck opening from inside, taken before insulation goes back.
Step 8: Close the loop
Confirm the inspection happened or is booked, file the photographs and the email with the job, and send the owner a two-line note saying who now warranties what. If the warranty maker needs notification, confirm whose job that was and that it was done.
Worked example: the bath fan on a warrantied roof, and the version that went wrong
The dialog above is the real sequence for a 4 in bath exhaust through a three-year-old shingle roof with a registered system warranty. Laid out by day:
- Day 1 (Thursday): the HVAC crew mounts the fan, runs insulated duct to a capped end 6 in below the deck at the planned spot, and measures the spot from the eave and the nearest gable so the roofer can find it from outside, without drilling a locator hole through a roof the crew agreed not to touch. About 3 hours on site.
- Day 1, same afternoon: the email goes out with the four answers. The roofer replies "confirmed" that evening.
- Day 5 (Monday): the roofer cuts the deck, installs the boot and reworks the shingles, about 1.5 hours. The HVAC tech returns at noon, connects and seals the duct to the boot collar, photographs the connection, and replaces the insulation. About 1 hour.
- Day 8: the permit inspection passes.
Total HVAC time across two visits is about 4 hours, against roughly 3.5 hours had they cut and flashed it themselves in one visit. The extra half hour is the price of the roofer standing behind the flashing.
The version that went wrong, on a different job: a tech cut a 4 in hole, slid a generic boot under the shingles, and sealed it with roof cement. It did not leak. Eighteen months later a storm stripped shingles from that slope, the homeowner filed a warranty claim, and the maker's inspector noted the unapproved penetration and excluded the surrounding area. The homeowner called the shop. Nobody in that conversation had a photograph, an email or a name.
What changes the answer: on a roof with no warranty and no living installer, or one the owner knows is out of coverage, the tech may flash it with the roof maker's own components and its instructions, with the same record. On a rated wall in a new building, the owner of the assembly is usually the GC's firestop subcontractor, and the right answer is often that your penetration is sleeved and left for them to seal with the project's listed system, because one firestop installer holding every penetration is what the inspection relies on.
How to verify you got it right
- The job record holds the other trade's name, the four answers and their written confirmation.
- Photographs show each layer you were responsible for, before it was covered.
- The owner has a note saying who warranties what from today.
- Nobody, including you, is guessing who sealed the deck.
References
- The roof, EIFS or encapsulation warranty for the specific house, for its alterations and penetrations clause.
- 29 CFR 1926.501 and 29 CFR 1910.28, fall protection, by activity.
- See related: The Penetration Record SOP; How to Seal a Roof Penetration That Will Not Leak; How to Move Through an Attic Without Stepping Through a Ceiling; How to Firestop a Penetration So the Rating Survives.