A project manager I know had a strip-out in a 1970s Mississauga office building go sideways on day one. Crew on site, machines staged, permits in hand. Then a question came up about the building’s designated substance list, and nobody had one. The job sat for most of a month while a consultant worked through the place sample by sample, and the general contractor ate the delay.
That story is common enough to be boring. It’s one of the most reliable ways an Ontario demolition or renovation loses its schedule, and every version starts the same way: somebody assumed the survey was paperwork they could catch up on later.
You can’t. Here’s what the rule says, why interior renovations trip it as often as full teardowns, and what a competent contractor will want settled before they quote.
Eleven Substances, and Your Building Probably Has Three
Ontario designates eleven substances under the Occupational Health and Safety Act: acrylonitrile, arsenic, asbestos, benzene, coke oven emissions, ethylene oxide, isocyanates, lead, mercury, silica and vinyl chloride. Read that list cold and you’d think it was written for refineries.
It wasn’t. Silica is in concrete, brick, block and mortar, so it’s in nearly every commercial structure in the GTA, and cutting any of it puts respirable dust in the air. Lead is in paint on anything finished before the late 1970s, and in old plumbing solder. Mercury sits in thermostats and fluorescent tubes. Asbestos shows up in drywall joint compound, vinyl floor tile, pipe wrap, ceiling texture, roofing felt and window caulking, often in the same building and in materials that look nothing alike.
That last point is why “we had it tested in 2009” isn’t an answer. A survey covers the materials a specific scope of work will disturb. Change the scope and you change the survey.
The List Comes Before the Bid
Here’s the part that catches owners out. The duty doesn’t sit with your demolition contractor. It sits with you.
The province’s guide to the Occupational Health and Safety Act sets it out in order. Before beginning a project, the owner must determine whether designated substances are present on the site and prepare a list of them. Where the work is tendered, that list goes into the tendering information. And before the owner enters a binding contract with a constructor, the constructor has to have a copy.
The sequence matters as much as the requirement. List, then bid, then contract, then work. Get it out of order and you haven’t only created a safety exposure. You’ve created a commercial one, because every bid you received was priced against an unknown.
Renovations Are Not Exempt
Plenty of owners hear “demolition” and file the requirement under teardowns. Interior work is where most of the trouble lives.
Pulling ceilings in a 1960s retail unit, opening a wall to relocate a washroom, taking up flooring ahead of a fit-out: all of it disturbs the exact materials a survey is meant to find. A full demolition at least forces everyone to slow down and plan. A tenant improvement job feels small, moves fast, and routinely puts a framing crew into a wall cavity nobody assessed.
What a Survey Actually Involves
A qualified consultant reviews whatever drawings exist, walks the space, and takes bulk samples of suspect materials — plaster, tile, mastic, insulation, paint — for an accredited lab. What comes back is a report tied to your scope: what’s present, where, in what quantity, and what has to happen before it’s disturbed.
If something turns up, abatement comes first and demolition follows. That isn’t a delay a contractor invented. It’s the only legal sequence. The value of surveying early is that abatement gets priced, scheduled and sequenced into the build instead of landing as a change order halfway through.
The Rules Change at the Provincial Line
Occupational health and safety is provincial, so the mechanics differ by jurisdiction. Most jurisdictions require a qualified person to identify hazardous materials before demolition or renovation disturbs them, but the name of the document, who must commission it and what triggers the obligation are not uniform. If you own buildings in more than one province, check the local regulator before you scope the work.
Where the Debris Goes Is Part of the Job
Once the hazardous materials question is settled, the next is what happens to everything else. According to Environment and Climate Change Canada, roughly 758,000 tonnes of construction, renovation and demolition material were diverted from disposal in 2022, a modest slice of the 9.9 million tonnes Canada diverted in total that year.
There’s room to do better, and growing pressure to. Municipal permit conditions and green building certifications both reward documented diversion, which means separating concrete, metal, wood and drywall on site and keeping the tickets. Selective deconstruction, taking a building apart in reverse rather than knocking it down, costs more in labour and returns more in salvaged material and lower tipping fees.
What to Ask Before You Sign
Ask who is arranging the survey and when. Ask whether the contractor is licensed and insured in the province, whether abatement is handled in-house or subcontracted, and how waste diversion will be documented. Ask what the plan is if something unexpected appears behind a wall, because on older buildings something usually does. Firms that handle the whole sequence — survey coordination, abatement, structural removal, disposal — tend to give straighter answers than ones that only swing the machine. That’s worth weighing when you compare demolition services from MAGCOR against anyone else on your shortlist.
The pattern in every stalled project is the same. Nobody wanted the survey to be real, so it got left until the trucks arrived. A week of assessment up front is cheaper than a stop-work order, and far cheaper than finding out what was in the ceiling after your crew has already breathed it.