A waterproofing bid reads clean on paper: below-grade membrane, dampproofing, insulation, all named against the wall sections and drawn in detail. What the drawings don't settle are three questions — and getting them wrong doesn't show up as square footage, it shows up as a claim once the wall's already backfilled.
1. What's in the system, and where does it stop?
Below-grade waterproofing is the core of the bid, and it's the one part every drawing set shows in section: sheet or fluid-applied systems on foundation walls and slabs, with protection board, drainage composite and terminations built to the detail. Dampproofing rides alongside it but prices and performs completely differently — extract which walls get which, since specs mix the language more often than they should. Foamed-in-place and rigid perimeter insulation round out the core scope, wherever the documents assign them here rather than to concrete or the general envelope package.
Two items drift depending on the tender. The whole-building air barrier sometimes rides inside the waterproofing package and sometimes ships with cladding — either answer is common enough that you can't assume, and the real cost is the transitions and tie-ins at every window and penetration, not the field of membrane. Traffic and deck coatings — parking membranes, balcony coatings, hot rubberized asphalt — are frequently priced here too, but carry their own system name, warranty and manufacturer certification, separate from the below-grade system on the same job.
And three things that look like waterproofing aren't. Roofing membranes and roof insulation are the roofing trade's entirely, including its own vapour retarder — the material can look identical to a below-grade membrane, but the trade line is drawn at the roof deck, not the material spec. Batt insulation in framed walls is usually drywall's. Waterstops in concrete joints are typically supplied and placed under the concrete trades, but confirm who specifically — real tenders disagree on this more often than "typically" suggests.
2. Who supplies the flashing, and is the substrate even ready for you?
Membrane through-wall flashings in masonry and cavity wall assemblies split cleanly by verb: masonry typically installs what waterproofing supplies. The trap, confirmed across real tenders, is that the supply side is frequently unowned by either trade — masonry assumes it arrives with the wall assembly, waterproofing assumes masonry orders its own material. Extract who supplies and who builds in, separately, per detail.
Then there's the schedule question sitting underneath all of it: a 14 to 28 day concrete cure requirement before membrane application is a precondition, not a footnote. It owns the schedule. Confirm it against the actual pour dates before assuming your crew can mobilize when the job plan says it can.
3. What has to happen after the membrane goes on?
Warranty terms, approved-applicator requirements, manufacturer site reviews and field adhesion testing carry real cost and real schedule dependency, and they're routinely stated once, separate from the system spec itself. Terminations at grade, tie-ins to roofing and cladding, and the detail condition at every penetration are each their own piece of labour, not a rounding error on the overall membrane area. And somebody has to protect the finished membrane and decide exactly when backfill is permitted to proceed — a site-work coordination question with a real cost if that sequence runs longer than planned.
Sharing the envelope
| Trade | What to reconcile before you price |
|---|---|
| Concrete & forming | Substrate finish quality, tie-hole treatment, kicker details and cure timing — all four decide whether the membrane can go on when the schedule says it can. |
| Site work | Backfill sequence and the handoff from your drainage board to their drainage pipe — confirm both ends of that connection are assigned to someone. |
| Roofing & cladding | Membrane tie-ins and air-barrier continuity at every interface where your system meets theirs — the failure point on most envelope warranty claims. |
| General contractor | Weather windows for application and who's responsible for protecting completed work once it's installed but not yet covered. |
Read the membrane spec for the system, then read Division 03 specifically for cure-time and substrate-acceptance language before trusting the schedule. Hunt the flashing details for supply-versus-install verbs rather than assuming the split is obvious, and check the warranty and manufacturer-oversight clauses before pricing labour that assumes a certified applicator wasn't required. The membrane spec tells you the system. The clauses scattered outside it tell you what has to happen before that system can go on the wall.