Why it matters
A former grow-op can be hard to finance and insure. Most major banks won't lend on one; a handful of credit unions will, sometimes at higher rates, and typically only once the home is fully remediated. Insurers often won't cover damage tied to a grow operation, and without insurance the mortgage falls through. Disclosure rules vary, British Columbia requires it on the property disclosure statement; some provinces don't require it, though undisclosed material defects can still be actionable.
How to spot it
Watch for a remediation or re-occupancy permit on file, patched holes in walls and ceilings from venting, mismatched or newer drywall in odd spots, circular water staining, strong air-freshener smells, modified electrical panels, and unusually high humidity or mould. Ask directly, and check municipal records.
What it costs
A clearance air test runs $250 to $900. Whole house mould remediation, which is the part of the work most likely to be needed, runs $10,000 to $30,000. The one government study that put a number on the whole job, from the City of Surrey, said $25,000 to $100,000, and that figure is in 2013 dollars, so treat it as a floor rather than a current estimate. A municipality may also charge its own remediation bylaw fee, $237 to $1,889 in Ottawa, plus an administration percentage. This card deliberately carries no electrical rewiring figure: the published Canadian ranges differ from each other by three to seven times, so there is nothing here worth quoting. Get a written scope and a quote instead.
What to do
Address it before you are firm. Order the municipal building file, not just an inspection: in the Surrey model the remediation record sits in the permanent building records, and in the Ottawa model an order can be registered on title and is only released when a certificate of compliance is issued. Ask for that certificate. Retain an environmental consultant with industrial hygiene certification rather than a general inspector. Get an insurance binder in writing before you waive financing, because a British Columbia court held in 2025 that an undisclosed grow operation was a material change of risk that justified voiding the policy. Assume the major banks are unavailable and line up a credit union or a broker early.
Education and triage, not a home inspection. Casaroo flags the visible signs and prompts the questions, a qualified inspector, electrician, and environmental pro confirm remediation. We flag; we don't certify a home.