Home Inspection Red Flags: What Buyers Should Watch For
A home inspection exists to catch the problems a showing won't reveal — issues hidden behind walls, under flooring, or in a crawlspace that only a trained inspector will flag before you close. This guide covers the red flags that come up most often in Canadian home inspections, which ones are typically negotiable, and which ones are strong reasons to walk away.
What a Home Inspector Actually Checks
A standard home inspection covers the structure, roof, exterior, electrical system, plumbing, heating and cooling systems, insulation and ventilation, and interior components like windows and doors. Inspectors visually assess and test what's accessible — they don't cut into walls or move furniture, so some issues can still be missed.
Structural Red Flags
- Diagonal cracks in foundation walls wider than a hairline, especially if they run through multiple courses of block or concrete
- Uneven or sloping floors, which can indicate settling, a compromised support beam, or joist damage
- Doors and windows that stick or won't close properly, often a sign the frame has shifted due to foundation movement
- Visible sagging in the roofline when viewed from the street, which can point to structural or long-term water damage
Not every crack is serious — hairline vertical cracks from normal concrete curing are common and usually cosmetic. What matters is width, direction, and whether it's actively growing.
Electrical Red Flags
- Knob-and-tube wiring, still found in some homes built before the 1950s — many insurers charge higher premiums or decline coverage outright until it's replaced
- Aluminum wiring, common in homes built in the 1960s and 70s, which requires specific connectors (or a full rewire) to be considered safe by modern standards
- Federal Pacific Electric (FPE) or other recalled/flagged panel brands, associated with a higher risk of breakers failing to trip
- Visible DIY wiring — exposed splices, missing junction box covers, or wiring not rated for its use
Electrical issues are worth taking seriously beyond cost: they're a leading cause of house fires, and some are also insurability issues that can affect whether you can get coverage at all, not just how much it costs.
Plumbing Red Flags
- Polybutylene piping, a plastic pipe used from the 1970s through the mid-1990s that's prone to failure and is flagged by most inspectors on sight
- Low water pressure across multiple fixtures, which can indicate galvanized pipe corrosion or a supply line issue
- Water stains on ceilings or around fixtures, even old and dry-looking ones, which point to a past or ongoing leak
- Visible corrosion or active leaks at supply lines, water heater connections, or under sinks
Roofing and Exterior Red Flags
- Missing, curling, or granule-bare shingles, which suggest the roof is near or past its expected lifespan
- A roof nearing or past typical asphalt shingle lifespan (commonly cited as roughly 15-25 years depending on climate and material), which affects both insurability and near-term replacement cost
- Poor grading around the foundation, where the ground slopes toward the house instead of away from it, a common cause of basement water intrusion
- Damaged or disconnected downspouts and eavestroughs, which concentrate water exactly where you don't want it
Moisture, Mould, and Ventilation Red Flags
Moisture problems are often the most expensive to fully resolve because the visible symptom is rarely the full extent of the issue.
- Musty odours or visible mould in a basement, crawlspace, or attic
- Efflorescence (white, chalky mineral deposits) on basement walls, indicating water has been moving through the concrete
- Poor attic ventilation, which can trap moisture and shorten roof lifespan even without an active leak
- Condensation on windows or evidence of past condensation damage, which can point to inadequate ventilation
When to Walk Away vs. Negotiate
Most inspection findings fall into a negotiating range rather than a deal-breaker. The distinction usually comes down to cost, safety, and whether the issue is isolated or systemic.
| Finding | Typical Response |
|---|---|
| Outdated but functional systems (older but working furnace, dated electrical panel) | Negotiate price or ask for a credit; rarely a reason to walk |
| Isolated repair items (a leaking faucet, a cracked window) | Minor negotiation point, sometimes not worth pursuing |
| Safety issues (knob-and-tube, FPE panel, active gas leak) | Require remediation or a significant price adjustment before closing |
| Structural movement or major systemic water intrusion | Get a specialist assessment before proceeding; can be a walk-away depending on scope |
An inspection contingency in your offer gives you the ability to negotiate repairs, request a price reduction, or exit the deal if something serious turns up — using that contingency, rather than skipping the inspection to compete in a hot market, is what protects you here.
How Much Does a Home Inspection Cost in Canada?
A standard home inspection in Canada typically costs $400-$700 for an average single-family home, with condos often at the lower end and larger or older homes at the higher end. Specialist follow-ups — a structural engineer, an electrician, or a mould assessor — are usually billed separately if the general inspection flags something that needs a closer look.
Frequently Asked Questions
What are the most common home inspection red flags?
Foundation cracks, outdated wiring (knob-and-tube or aluminum), plumbing issues like polybutylene pipe, roof age, and signs of moisture or mould come up most often across Canadian home inspections.
Should I walk away from a home with knob-and-tube wiring?
Not necessarily, but treat it seriously — many insurers require it to be replaced or charge higher premiums, so factor rewiring cost and insurability into your offer or negotiation rather than treating it as purely cosmetic.
How much does a home inspection cost in Canada?
Typically $400-$700 for a standard single-family home, with condos often at the lower end and larger or older properties at the higher end.
Can a home inspection find every problem?
No. Inspectors assess what's visible and accessible without cutting into walls or moving furniture, so some issues — particularly ones hidden behind finished surfaces — can still be missed. Specialist assessments exist for exactly this reason.
Is a home inspection worth it if I'm buying new construction?
Yes. New builds can still have installation defects, code violations, or unfinished work that a pre-delivery inspection or a full home inspection can catch before your warranty coverage windows start ticking.
Next Steps
If you're buying a condo rather than a house, review our guide to what a status certificate covers — it reveals financial and legal risks an inspection alone won't catch. And if you're selling rather than buying, see our home staging checklist for what actually affects resale value. Use our Mortgage Calculator to model payments once you're ready to make an offer.