Two documents price a demolition job, and estimators reach for the wrong one first. The demolition drawings are the intuitive read: walls, finishes, equipment and openings, marked up and keynoted, ready to measure. The designated-substances survey (DSS) is the one that sets the real price: it tells you what operation class you're running under, what protective measures that class demands, and what happens when its assumptions turn out wrong once the walls come open. Below is both documents, read in the order that keeps you from missing the expensive one.
Four things nobody argues about
- Building demolition: complete to whatever limit the documents state, typically slab, foundations, below-grade services. That limit is worth extracting explicitly; "demolish the building" and "demolish the building including its foundations" are different scopes at a very different price.
- Selective and interior demolition: the drawn removals per the plans and their keynotes. Reads cleanest off the drawings, and the most likely spot for a genuine keynote conflict buried in a large set.
- Designated-substance abatement: asbestos, lead, mould and other designated substances per the DSS, priced by type, condition, location and operation class. The highest-stakes line in the bid. See below.
- Disposal, manifests and documentation: waste classification, transport manifests, receiving-facility records, clearance documentation. Real administrative labour with a real cost, not paperwork riding free alongside the truck.
- Dust, noise and containment control: enclosures, negative air, decontamination facilities, monitoring, sized to the operation class. A Type 3 asbestos operation and a Type 1 are not the same containment bid, even on the same floor area.
Read the DSS report first
Quantities, material conditions, what's assumed versus confirmed — and, critically, the gap language describing what happens when a substance turns up that the survey didn't anticipate. That last clause is often the single most consequential paragraph in the tender for this trade.
The report also carries the regulatory classes and notification periods: operation classes such as O. Reg. 278/05 Type 1, 2 or 3, the notification lead times attached to each, and who files them. Those set both the protective-measures cost and the schedule float before work can even begin. Sitting alongside it, usually, is the air-monitoring and clearance arrangement: who provides the monitoring consultant, what clearance criteria apply, and, worth hunting for specifically, who pays when a clearance test fails and containment has to be re-cleaned and re-tested. On occupied or tightly-sited urban projects, add pre-condition surveys and vibration limits (adjacent-property condition surveys, vibration monitoring, crack thresholds), which add real monitoring cost a demolition-only read of the drawings won't surface.
Then walk the drawings for extent, not quantity
Once the DSS has set the class and the cost of protection, the drawings tell you where the boundary of demolition sits. That's a different question than how much there is to remove. Every place a hatch boundary, a keynote and the physical site disagree with each other is a dispute waiting to happen, and every "to remain" note next to a removal deserves individual extraction rather than trust that it's consistent across the set. This is where a large drawing package hides its real ambiguity: not in the quantities, which are usually clean, but in exactly where demolition is meant to stop.
The floating items
A handful of tasks don't sit cleanly in either document, and each one is a common source of an unpriced gap. Engineered shoring for selective structural removals (a new opening in a load-bearing wall, a slab section removed) is inconsistently assigned: sometimes delegated engineering under the demolition contract, sometimes structural's, sometimes the GC's. Extract the delegation exactly as stated, and treat silence on it as a finding to raise before pricing, not an invitation to assume either answer.
Saw-cutting and coring for new mechanical, electrical or structural openings is the other genuine floater: sometimes a lump obligation carried by demolition, sometimes carried individually by whichever trade needs the opening. An ambiguous tender produces the worst kind of gap here: every trade assuming coring is someone else's line, discovered only when nobody shows up to cut the hole. Extract who carries it and whether the assignment holds job-wide or varies opening by opening.
Salvage and reuse (fixtures, equipment or architectural elements the owner wants protected and turned over) adds real handling cost and real liability a straight demolition quantity doesn't capture; a salvaged item damaged in removal is a claim, not a rounding error. Extract the salvage list and the stated care standard specifically.
Three more sit outside your scope but still need confirming: utility disconnects follow the utility's own process and timeline, not your schedule, though the arrangement and any fee obligation are worth extracting as real project-schedule risk. Contaminated soil remediation, where assigned to site work or a separate environmental contract, stays there: confirm precisely where excavated soil ends and built-material abatement begins, since the two get lumped together in conversation far more than the documents lump them in scope. And capping and making safe by the mechanical and electrical trades has to happen, and be certified, before demolition proceeds against those services: confirm it happens, not just that it's assigned to someone.
Who you're sharing the site with
| Trade | What to reconcile before you price |
|---|---|
| Site work | Grade restoration after demolition, backfill of removed basements, and haul routes shared across both scopes. |
| Mechanical & electrical | Service capping certification before demolition proceeds: confirm it happens, not just that it's assigned. |
| General contractor | Phasing around occupied adjacencies, and who owns and maintains the hoarding between demolition and the work that follows it. |
| Environmental consultant | Monitoring schedule, clearance criteria, and how disputed report interpretations get resolved before they become schedule delays. |
Read the DSS report cover to cover before pricing a single removal off the drawings: it sets the operation class, the containment cost and the language that decides who pays when the walls don't match the survey. Then walk the demolition plans specifically for "to remain" notes and unassigned saw-cutting. The drawings tell you what to remove; the DSS and the regulatory documents around it tell you what removing it is going to cost.