Top 5 Home Inspection Red Flags in the GTA (2027)

By Jatin Dua · Broker of Record, RE/MAX Quantum Realty · Updated 2 November 2026 · 10 min read — The five home inspection findings that matter most in GTA homes, what each means for insurance and cost, and when to walk away.

This is for buyers in Toronto and across the GTA who have a home inspection booked, or a report in hand, and want to know which findings really matter. You will get the five red flags I take most seriously, what each one usually means for cost, insurance and safety, who can confirm it, and when to negotiate or walk away.

Which home inspection red flags matter most in the GTA?

Every inspection report lists problems. Most are small: a loose railing, a dripping tap, caulking that needs redoing. The five below are different, because they can affect your safety, your ability to get home insurance, or your budget for years. They also show up often in the GTA’s older housing, from pre-war houses in central Toronto to 1960s and 1970s homes across the suburbs.

Source: Electrical Safety Authority, Health Canada, City of Toronto lead and basement flooding pages, checked November 2026.

Inspectors vary a lot in how thorough they are. A good inspector flags these issues and tells you who to call next. If you have not booked one yet, my guide to what a home inspection costs in Ontario covers fees and how to choose one.

1. Is water getting into the basement?

Water is the red flag I worry about most, because it is often a symptom. The cause may be outside the house, under it, or in the sewer connection. Signs an inspector may point out include:

• stains, peeling paint or a white chalky crust low on basement walls;
• a musty smell, warped flooring or new paint in only one corner;
• cracks in the foundation, especially ones that are wide or show past leaking;
• soil that slopes toward the house, or downspouts that empty against the wall;
• no backwater valve or sump pump in an area with a flooding history.

A fresh finished basement can hide all of this. Ask the seller directly whether the basement has ever taken on water and whether an insurance claim was made. In Toronto, the Basement Flooding Protection Subsidy covers 80% of invoiced cost for eligible work done on or after 12 November 2025, up to $6,650 per property, including up to $1,600 per backwater valve (up to two) and up to $2,250 for a sump pump. Other GTA cities run their own programs, so check with the city where you are buying.

What to do: if the report shows active or past water, get a plumber or waterproofing contractor to look before your inspection condition ends. A sewer camera scan of the drain to the street is worth the extra cost on older homes.

2. Does the house have knob-and-tube or aluminum wiring?

Old wiring is the red flag most likely to cause an insurance problem.

Knob-and-tube

The Electrical Safety Authority (ESA) says knob-and-tube wiring was used in homes from the early 1900s to the 1940s. ESA says it can be safe if a Licensed Electrical Contractor maintains it properly, and the current electrical code does not force owners to remove it. The catch is insurance: ESA notes that many insurers will not provide or renew coverage on homes with this wiring, and some require it to be replaced first. Older systems also lack modern protection such as ground fault circuit interrupters in bathrooms and outdoors.

Aluminum wiring

ESA says homes built from the mid-1960s to the late 1970s may have aluminum branch wiring. It is permitted and can be safe when the connections are done correctly with devices approved for aluminum. Again, insurance is the issue: some insurers want an ESA inspection and a Certificate of Acceptance before they will cover the home.

What to do: call two or three insurers during your conditional period, before you firm up. If either wiring type is suspected, have a Licensed Electrical Contractor assess it. My full guide to knob-and-tube and aluminum wiring in Ontario explains the steps.

3. Is there asbestos or vermiculite insulation?

Health Canada says asbestos was used mainly before 1990 for insulation and fireproofing. In older homes it can be in vermiculite attic insulation, pipe and boiler wrap, some floor and ceiling tiles, plaster, siding and roofing. Health Canada’s position is that there is no significant health risk if these materials are left undisturbed or sealed off. The risk comes when they are drilled, sanded, cut or torn out during renovations.

Vermiculite looks like small, light, pebble-like granules, often grey-brown or gold, poured between attic joists. Health Canada advises not to use the attic for storage, not to disturb the material, and to hire trained professionals if you plan to renovate.

What to do: an inspector usually cannot confirm asbestos by looking. If you plan to renovate the attic, basement or kitchen, budget for professional testing and, if needed, removal by a qualified contractor before you set your offer price.

4. Does the home have a lead water service pipe?

This one matters most in older Toronto neighbourhoods. The City of Toronto says homes built before the mid-1950s may have a lead water service pipe, the line that brings water from the street into the house. Buildings with more than six units do not have lead service pipes. Lead can also come from solder used before 1990 and from older brass fixtures.

Ownership is split. The City owns the pipe from the watermain to the property line, and the homeowner owns the part from the property line into the house. Toronto Public Health recommends replacing both parts at the same time, and the City runs a priority program where it replaces its side when the owner commits to replacing the private side. The City also offers free lead testing.

The City says a pipe that is grey, scratches easily and does not sound hollow when tapped may be lead. A licensed plumber can confirm it. My guide to lead water service lines in Toronto walks through the program in detail.

What to do: ask the seller whether the line has been replaced, and get a plumber’s quote for the private side if it has not. This is a fair point to negotiate on price.

5. Are there roof, attic or ice damming problems?

An inspector should look at the roof covering, flashing, the attic and its insulation and ventilation. Water stains on the attic sheathing, damp or matted insulation, or mould spots on the underside of the roof are signs of a moisture problem. In winter, heavy icicles and ice along the roof edge are clues too.

The Insurance Bureau of Canada says ice dams form when heat from the house melts snow on the roof and the water refreezes at the cold edge. The main causes it lists are poor attic insulation, poor ventilation, and heavy snow with blocked eavestroughs. It also notes that sudden water damage from ice dams is commonly covered, while ongoing or repeated damage may be treated as a maintenance issue and not covered.

What to do: ask for the roof’s age and any receipts. If the attic shows moisture, get a roofer’s opinion before your condition expires.

Which red flags are deal breakers, and which can you negotiate?

In my experience, a finding becomes a deal breaker when one of three things is true:

• You cannot insure the home on reasonable terms before closing, which can also put your mortgage at risk.
• The fix is open-ended, such as active water with no clear cause, or a structural crack an engineer will not sign off on.
• The cost is beyond your cash cushion after closing costs, and the seller will not adjust.

Most other findings can be handled with a price reduction, a credit on closing or a repair before closing. My guide on how to negotiate after a home inspection in Ontario covers which option suits which problem.

What will a standard home inspection not find?

A visual inspection does not open walls or test the air. Three things often need a separate step:

• Radon: Health Canada’s guideline is 200 becquerels per cubic metre, and it recommends fixing levels above that within a year. A proper test runs at least 91 days, ideally in the heating season, so it rarely fits inside a condition period. Plan to test after you move in.
• The sewer line: only a camera scan shows roots, breaks or a collapsed pipe under the lawn.
• Asbestos content: only lab testing confirms it.

For more on this, see what a home inspection does not cover in Ontario.

What to do next

1. Book an inspector who will flag these five issues and tell you which specialist to call.
2. Ask the seller in writing about past water, wiring updates, a lead line replacement and the roof’s age.
3. Call your insurer during the conditional period with the home’s age, wiring type and heating system.
4. Get written quotes for any major finding before your condition expires, then negotiate with those numbers.
5. After closing, run a long-term radon test through the heating season.

Frequently asked questions

Sources

• Electrical Safety Authority: Knob and Tube Wiring
• Electrical Safety Authority: Aluminum Wiring
• Health Canada: Health risks of asbestos
• City of Toronto: Lead in drinking water
• City of Toronto: Basement Flooding Protection Subsidy Program
• Health Canada: Guide for radon measurements in residential dwellings
• Insurance Bureau of Canada: Understanding and helping prevent ice dams
• RECO: Competing offers

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