What are the red flags in an older Toronto house?
Knob-and-tube wiring, a sixty amp service, galvanized supply pipes, a clay drain line under mature trees, an underdug basement without proper underpinning, vermiculite insulation, and any unpermitted basement apartment.
Caution: What we have not checked
Toronto's housing stock is old and each era brought its own liability.
Knob-and-tube and sixty amp service: pre-war electrical. Insurers surcharge or decline, and a full rewire plus service upgrade is a five figure job.
Galvanized supply and clay drains: galvanized corrodes shut from the inside. Clay laterals crack and fill with roots under mature trees, and a sewer line replacement across a front yard is expensive and disruptive.
Underpinning done badly: lowered basements are common and valuable, and done without engineering and permits they are a structural problem you cannot see. Ask for the permit and the engineer's drawings.
Vermiculite insulation: may contain asbestos, and testing plus abatement is a real cost.
Unpermitted basement apartments: the rental income is not income a lender will count and the fire code liability transfers to you.
None of these should necessarily stop you. All of them should be priced, with a written quote, before you waive conditions.
Next questions
What is knob-and-tube wiring and does it matter?
Pre-1950s wiring with no ground, insulated with cloth and rubber that becomes brittle. It matters mainly because insurers surcharge, condition or decline on it, and a full replacement is a five figure job.
Ontario
How worried should I be about signs of water in a basement?
Worried enough to price it. Surface causes like grading and downspouts cost hundreds to fix. A failed weeping tile system or a cracked foundation means interior or exterior waterproofing, which runs from several thousand to well over twenty thousand.
Ontario
How do I know if a basement apartment is legal?
Ask for the building permit and its final inspection, not the tenant's rent receipts. Which rules the unit has to meet depends on when it was created, so the permit file is the only thing that settles it.
Ontario