A roofing bid looks self-contained in a way most trades don't: the roof plan shows the assembly, the details show the flashing conditions, and the field of the roof prices out cleanly from a takeoff. The risk isn't in the field — it's at the edges, literally. Every curb, drain, parapet and penetration is a place where roofing's scope touches somebody else's, and the attachment requirements that decide how much fastener and adhesive the field actually needs are frequently a wind-engineering exhibit sitting apart from the roof plan entirely.
This is a working list of where those edges sit, built from what actually shows up across real Canadian ICI tenders — not a systems catalogue, a list of the specific boundary questions worth answering before the number leaves the office.
What's reliably yours
- Membrane roofing system complete — the specified assembly bottom-up: vapour retarder, insulation and tapered packages, cover board, membrane and surfacing, per roof area and detail. Confirm who designs the tapered layout and the minimum R-value required at drains, since both change the insulation takeoff independent of the membrane spec.
- Base and cap flashings — membrane flashing at every upstand, curb and penetration, plus metal counter-flashings and copings wherever they're assigned to this scope rather than to cladding. This is where roofing labour actually concentrates; the field membrane rolls out fast, the flashing details don't.
- Roof specialties and accessories — walkway pads, pitch pockets, breather vents, gum boxes: the per-each list the roof plan scatters across dozens of small callouts rather than gathering in one schedule, which is exactly why it's easy to under-count.
- Manufacturer warranty — the term and type demanded, with its inspection and approved-applicator conditions. Warranty language is price: a 20-year NDL warranty with mandatory manufacturer inspections costs differently than a materials-only warranty, and the tender rarely states that difference in dollars.
Where the fight actually happens
Metal roofing — split from the membrane package, or not
Standing-seam or profiled metal roofing shows up on plenty of ICI tenders as a distinct roof area from the membrane system — a canopy, an entry feature, a mechanical penthouse — and specs handle the ownership inconsistently. Sometimes it's priced with the membrane trade as one roofing package; sometimes it's a dedicated metal roofing sub carrying its own system and warranty. Extract which this tender is before pricing, and don't assume the answer from the last job that looked similar.
Temporary roofing and phased cutoffs
Phased construction — additions, partial reroofs, sequenced areas on an occupied building — usually needs temporary membranes and night seals to keep water out between work sessions. This is real labour and material that a straight roof-area takeoff won't show, because it's driven by the construction schedule, not the roof plan. If the phasing plan implies more than a handful of cutoffs, price the cutoffs themselves, not just the finished area.
Fall-arrest anchors — whose engineering, whose install
Roof anchors for fall protection carry an engineering and certification duty that's separate from the physical install, and the split between them isn't consistent across tenders. Sometimes the anchor system is engineered and supplied by a specialty fall-protection vendor with roofing simply installing and flashing it; sometimes roofing carries the whole package including the certification. Confirm which before assuming the anchor line is a minor accessory — a certified system with engineering sign-off is a different cost than a stock anchor bolted through the deck.
The other half: what isn't yours, even when it looks close
- Roof drains and plumbing — the drain body itself is plumbing's, supplied and set by that trade. Flashing into the drain — the membrane detail that actually keeps water out — is roofing's. Both halves of that split need to be extracted separately, because it's common for both trades to assume the other carries the whole assembly.
- Curbs and wood nailers — curb construction is rough carpentry's or mechanical's supply, not roofing's. Extract the sizes anyway: every curb on the roof plan is flashing labour for you regardless of who built the box underneath it, so the curb schedule matters to your takeoff even though the curb itself isn't your line item.
- Skylights and hatches supply — the units themselves are frequently supplied by others where the documents assign them that way, with curb flashing and integration staying in roofing scope. The nuance is that "supply by others" doesn't mean "no roofing cost" — the flashing and integration labour is often the larger number anyway.
Three things that hide outside the roof plan entirely
- Wind uplift and attachment requirements. FM or RC-4 style uplift ratings, with enhanced attachment at perimeters and corners, live in a wind engineering exhibit or a general note rather than on the roof plan itself — and attachment density is what actually prices the field of the roof, not just the membrane spec. A perimeter zone with double the fastener count changes labour across the whole edge condition, not just at the corners.
- Existing conditions on reroofing. Core cuts, wet-insulation allowances, deck condition language and unit rates for deck or insulation replacement are the difference between a clean tear-off and a job that opens up unknowns as soon as the membrane comes off. If the tender doesn't state a unit rate for replacement, that's the finding to flag before pricing a lump sum against an assumption.
- Traffic and protection during construction. Other trades working over a finished roof — mechanical setting rooftop units, cladding building parapets — need protection in place, and damage responsibility needs an owner. This is a Division 01-adjacent coordination item more often than a roofing-section line, and it's easy to miss because it only becomes a cost once someone else's trade is actually up there.
Who you're actually sharing the roof with
| Trade | What to reconcile before you price |
|---|---|
| Mechanical | Curb sizes and locations, equipment set sequence after membrane is in, and the full penetration schedule before flashing quantities are final. |
| Plumbing | Drain locations and sump details — confirm the drain body and the flashing-in are priced by the correct trade on each side of the split. |
| Cladding | Parapet and roof-to-wall transitions, and coping ownership specifically — a detail that gets drawn once and claimed by neither trade if nobody checks. |
| General contractor | Staging, phasing cutoffs, and protection of completed roof areas once other trades are working above them. |
The pass that catches most of this
Read the roof plan and details the way they deserve, then go find the wind engineering exhibit and the curb schedule specifically — they're rarely on the same sheet as the assembly you just took off. Check every curb, drain and penetration against who actually built it, because the flashing labour is yours regardless of who supplied the box underneath. The assembly is the easy part of a roofing bid; the edges are where the number either holds or doesn't.