Why it matters
In homes insulated decades ago, the formaldehyde off-gassing has largely dissipated, and research has not found cured UFFI to be a significant ongoing health hazard. The practical issues today are disclosure and resale: UFFI often must be disclosed, it can make some buyers and lenders wary, and, because the foam can hold moisture in a wall cavity, it can contribute to hidden rot where there is a water problem.
How to spot it
You usually can't see it, because it's inside the walls. Clues include a UFFI test or disclosure in the paperwork, off-white foam visible at removed outlets or along the attic wall-top, and a home insulated in the late 1970s. A certified test (air sampling or a core sample) confirms it.
What it costs
Formaldehyde air testing with accredited lab analysis runs $250 to $875, or about $500 for an attended professional test. There is no defensible Canadian figure for removal, and this card deliberately publishes none: the only two numbers on the open web disagree with each other by roughly two times, are undated, and cite nothing. That matters less than it sounds, because removal is not the recommended course for intact material in the first place.
What to do
Treat it as a disclosure and negotiation question rather than a remediation project. In Ontario the standard agreement of purchase and sale still carries a seller representation and warranty about urea formaldehyde that survives closing, so the contract is where this lives. In Quebec the seller declaration form is mandatory and names it directly. If you want certainty, pay for an air test rather than a removal quote. If the foam is wet or breaking down, that is a moisture problem to fix at its source, and the material should come out as part of that.
Education and triage, not a home inspection. Casaroo prompts the UFFI question for late-1970s homes, a certified tester confirms it and an inspector checks for moisture. We flag; we don't test.