Roof Penetration Added for Another Trade

Purpose

When another trade needs a hole in a roof, the hole becomes yours. The leak that follows arrives at the roofer whoever held the saw. This procedure clears the cut against framing before it is made, reads what the blade actually hit from the attic side before anything covers it, dries the opening the same day rather than overnight on sealant, and leaves a file that says who cut what.

The failure this prevents is the Friday penetration: a stub through the deck, a smear of cement, a weekend of rain, and a Monday argument between two contractors while the ceiling comes down.

Scope

Covers a new penetration cut through an existing roof for another trade - a vent, a flue, a line set, a conduit, an equipment mount - on steep-slope shingle and small low-slope roofs, residential and small commercial: the coordination agreement, location, structural verification, dry-in and permanent flashing.

Does not cover replacing an existing failed boot or flashing, or the curb, chimney and skylight details, each of which has its own SOP, nor the other trade's equipment and connections, nor engineering a structural repair, which this procedure routes but does not perform.

Roles and responsibilities

Who cuts is a decision, and it has one right answer

The roofer cuts, flashes and closes; the other trade sets its equipment. That is not territorial: the person who cuts is the only one who knows what the deck did when the blade went through, and a flashing set into an existing field has to be woven under the courses above it, which is roofing work with a roofing sequence. Where the schedule forces the other trade to cut, step 1's commitments go in writing first. A caulked stub is not a dry-in, it is a leak with a start date.

What a manufacturer's system warranty covers after a third party opens the covering is a question for that warranty document and, where real money is involved, for the customer's own attorney, not for a crew on a roof. What the shop can bank is a dated record of what was cut, by whom, where, and what flashing went around it, and that is what separates the trades if a ceiling ever stains.

Procedure

1. Get the coordination agreement before anyone is scheduled. Establish in writing who cuts, who flashes, who is on site which day, and that no fastener from the other trade lands in the field outside the flashing. Acceptance: that agreement in the file, naming the cutting and flashing parties, carrying the same-day dry-in commitment, acknowledged by the customer. Wrong looks like a phone call between two foremen. Stop rule: no agreement means the roofing crew does not attend, and the customer is told why. Hazard, commercial: without it the shop inherits an unflashed hole and no evidence it did not make it.

2. Set access and fall protection, and treat the opening as a hole from the moment it exists. Access runs under the ladder setup standard and the fall protection setup SOP. Acceptance: anchorage set, everyone connected, and a compliant cover on the roof before the first cut. Wrong looks like a cover fetched after the hole is open. Stop rule: no cut until the cover is on the roof. Hazard: a fresh opening is a hole under 29 CFR 1926.501(b)(4), and any cover must meet 1926.502(i) - capable of supporting at least twice the expected load, secured against displacement, and marked; the duty for the surrounding work triggers at 6 ft, under whichever provision fits the roof: 1926.501(b)(13) for residential construction, (b)(11) for a steep roof that is not residential construction, and (b)(10) for a low-slope roof, where a warning line with a safety monitor is an accepted alternative to conventional fall protection.

3. Locate the penetration against flow, clearance and structure before it is marked. Keep it clear of valleys, out of the wash below a chimney, dormer or upper wall, and off ridges and hips by the distance the flashing instructions require, then transfer the framing positions from the attic and mark where the cut misses every rafter, chord and web. Acceptance: a marked location with framing positions transferred, and clearance to the nearest valley and any up-slope wall recorded. Wrong looks like a hole located from below by someone standing in a bathroom. Stop rule: a location that cannot clear framing gets moved, and if it cannot be moved the job stops for a design decision. Hazard: the cut sits over an attic full of wiring, ducts and plumbing, so the space beneath is inspected first and blade depth is set to the sheathing thickness only.

4. Cut, then verify what the blade actually hit. Make the cut, or inspect the other trade's cut, then look at the opening from the attic side before anything covers it. Acceptance: confirmation from below that no rafter, truss chord or truss web is cut, notched or bored, and no wiring, duct or pipe was struck. Wrong looks like flashing set over a hole nobody viewed from underneath. Stop rule: any cut, notched or bored engineered truss member stops the work; a truss is not repaired by field judgment, so the opening is covered, the customer is told, and a repair detail comes from a design professional. Hazard: cutting sheathing and framing releases wood dust, an inhalation route, so use dust extraction or work upwind with respiratory protection under a written program per 29 CFR 1926.103; on an older low-slope roof the felts and mastics can contain asbestos, which is a separate survey and a separate contractor.

5. Dry in the same day, and never leave a stub on sealant. Before the crew leaves, install the permanent flashing or set a self-adhered membrane dry-in around the penetration, lapped down-slope, with the courses above temporarily lapped over its top edge. Acceptance: no upward-facing edge anywhere in the temporary assembly, membrane bonded to clean dry deck, dry-in method and date in the file. Where a step 4 stop has put a fall cover over the opening, the dry-in goes down first and the cover is refastened over it, its fasteners landing outside the bonded area or sealed as driven, and the acceptance is judged on the assembly as left, cover included. Wrong looks like a stub, a bucket of cement and a forecast. Stop rule: deck too wet or cold to bond means a mechanically fastened and weighted cover instead, with the customer told the roof is temporary until the return date. Hazard: soldering, brazing or torching here is hot work on membrane and felt, both of which ignite, so it runs under a hot work permit and fire watch per NFPA 51B in the edition your authority having jurisdiction or the property's insurer requires, and nobody leaves until the watch period is over.

6. Install the permanent flashing woven into the courses. Use the flashing designed for this penetration - a boot per the pipe boot and vent flashing replacement SOP, a curb for equipment or a cluster, a target patch on membrane - lifting the courses above per the shingle repair and blend-in standard so the flange runs under them. Acceptance: flange over the course below and under the course above, fasteners only where covered, flashing matched to the penetration, not improvised. Wrong looks like a surface-mounted plate sealed to the shingles. Stop rule: a pourable sealer pocket is used only where the geometry genuinely cannot take a flashing, and then it is recorded as a maintenance item with an inspection interval. Hazard: cut metal and membrane edges are laceration points and offcuts slide, so gloves stay on and scraps are pouched as they are cut.

7. Close out, and confirm the other trade did not fasten through your field. Remove and reconcile every temporary cover, hand seal the shingles you unsealed per the shingle repair and blend-in standard, then walk the area for the other trade's fasteners, straps, brackets or clips landing in the field outside the flashing. Acceptance: covers reconciled to zero remaining, tabs tug-tested and holding, and zero unflashed fasteners, each one found removed and its hole patched or flashed. Wrong looks like a finished penetration with four unflashed lag screws holding a strut 2 ft up-slope. Stop rule: a fastener that cannot come out because it carries the other trade's equipment stops the sign-off until that trade returns and supports it properly. Hazard: this step releases the assembly to weather, so nothing is left unsealed that cannot be resealed before the crew goes.

The record this produces

A penetration entry carrying: the coordination agreement and who cut; the marked location with clearance to the nearest valley and any up-slope wall; framing positions from the attic, the attic-side verification result and anything struck; the dry-in method and date; the flashing type, size and manufacturer; covers placed and removed; shingles lifted and hand-sealed; and the fastener walk result and its resolution.

Worked pass: 2 in plumbing vent for a new bathroom, 6:12 shingle roof

The plumber's schedule required them to cut, so step 1's agreement names the plumber as the cutting party, the roofing crew on site the same day, and no plumbing fasteners in the field. Step 2: anchorage set, marked cover staged before any cutting. Step 3: the roofer marks the location 6 ft from the nearest valley centerline and clear of the dormer wash, truss positions transferred from the attic and marked on the deck at 24 in on center. The plumber cuts while the roofer is on another elevation, about 4 in off the mark.

Step 4 fails. From the attic side the hole is 3-1/2 in across for a 2 in DWV pipe measuring 2.375 in outside, and it has taken 1-1/2 in out of the 3-1/2 in width of a truss top chord, which is 43 percent of that member's width. The stop rule fires: no flashing goes in, the opening is covered under the step 2 cover, the customer and the plumber are both told in writing that afternoon, and a repair detail comes from a design professional, not a scab plate screwed on by whoever is closest.

Step 5 still runs that day: a self-adhered dry-in over clean dry deck around the pipe, every lap facing down-slope, courses above temporarily lapped over its top edge, the cover refastened over it, date in the file. Nothing is left overnight on cement.

The crew returns after the engineer's reinforcement is installed and inspected. Step 6: the pipe measures 2.375 in outside, so the boot labelled for 2 in pipe is correct, and its printed 3:12 to 12:12 range contains the 6:12 slope. Two courses lifted, five shingles unsealed, flange over the course below and under the courses above, all six fasteners covered. Step 7: five shingles hand-sealed at four spots each, twenty dabs, all five holding; one cover in and one out; the fastener walk finds two plumbing strap screws in the field 18 in up-slope, both removed and their holes patched before the courses closed over them.

The 43 percent is what made this stop worth taking. Nothing on the finished roof would have shown it, the boot would have looked correct, and the shop would have signed off over a compromised truss chord it had covered up itself.

References

• 29 CFR 1926.501(b)(4) for fall protection at holes and 1926.502(i) for cover strength, securing and marking at a new roof opening; 1926.501(b)(13), (b)(11) and (b)(10) for the surrounding roof work depending on roof type, with 1926.502(d) for personal fall arrest
• 29 CFR 1926.103 for the written respiratory protection program any respirator used for dust control is worn under
• NFPA 51B, in the edition your authority having jurisdiction or the property's insurer requires, for hot work permits and fire watch where another trade torches at the penetration
• See related: the pipe boot and vent flashing replacement SOP, the shingle repair and blend-in standard, the low-slope repair standard, and the flashing and penetration detail inspection SOP