The Calgary Home Defects Guide: 20 Issues We Find Most Often
Calgary homes fail in predictable ways. Clay soil that swells and shrinks, 30-plus freeze-thaw cycles a year, hailstorms every summer, chinooks that melt and refreeze a roof in a single day, and construction booms in the 1970s and 1990s that each left behind their own signature materials. After thousands of inspections across the city, the same twenty issues keep coming back. This guide covers what each one looks like, why it happens here, and the typical Calgary repair range so you can judge whether a finding is a bargaining chip or a walk-away.
Repair ranges are typical Calgary contractor figures for planning purposes only — always get a quote before negotiating.
Structure, foundation and site
1. Negative grading against the foundation
The single most common finding in Calgary. Soil settles over the first decade and slopes back toward the house, so meltwater and rain drain into the foundation instead of away from it. The result is chronic basement moisture, efflorescence on the walls and, in bad cases, differential settlement. You want a minimum 6-inch drop over the first 10 feet. Typical fix: $500–$3,000 for regrading and downspout extensions.
2. Foundation cracks in clay soil
Hairline vertical shrinkage cracks in a poured wall are normal. Horizontal cracks, stair-step cracks in block, or cracks wider than a quarter inch that continue through the floor slab suggest movement driven by Calgary's expansive clay. Typical fix: $600–$1,200 per crack injection; $10,000+ for structural underpinning. See our deeper write-up on grading and foundation moisture.
3. Deck ledger and footing problems
Decks bolted to rim joists with lag screws instead of proper through-bolts, no flashing behind the ledger, and footings that never reached Calgary's 4-foot frost depth. Frost heave lifts the deck a little each winter until the ledger tears at the house. Typical fix: $800–$5,000.
4. Settled or heaved garage slabs and walkways
Heaving concrete that traps a garage door open or channels water back to the house. Common in neighbourhoods built on poorly compacted fill. Typical fix: $1,500–$6,000 for mudjacking or replacement.
Plumbing
5. Poly-B (polybutylene) supply piping
Grey plastic supply lines installed in Calgary homes roughly between 1985 and 1997. The pipe and its acetal fittings degrade with chlorinated water, and failures usually appear at fittings without warning. Many insurers now surcharge or refuse coverage. Typical replacement: $6,000–$15,000 for a full repipe. Details in our Poly-B guide.
6. Cast iron and clay sewer lines
Inner-city Calgary — Bridgeland, Killarney, Renfrew, Elbow Park — is full of pre-1970 drain lines with scale build-up, bellies and root intrusion. Nothing about it is visible from inside the house, which is why a sewer scope is worth the $200. Typical fix: $5,000–$25,000 for a line replacement.
7. Failed or missing backwater valve
Calgary requires backwater valves in new construction, but many older basements have none — and a good number of installed valves have never been serviced. Typical fix: $2,000–$4,500 retrofit.
8. Water heaters past end of life
Tank heaters last 10–13 years here. We regularly find 18-year-old tanks with corroded fittings, improper venting or missing expansion tanks. Typical fix: $1,600–$3,000.
Electrical
9. Aluminum branch-circuit wiring
Homes built roughly 1965–1978. Aluminum expands and contracts more than copper, loosening connections at outlets and creating heat. It's insurable and safe when properly pigtailed with approved connectors — but only when it's been done everywhere. Typical remediation: $2,000–$6,000. Full detail in our aluminum wiring guide.
10. Missing GFCI and AFCI protection
Kitchens, bathrooms, garages, unfinished basements and exterior outlets should be GFCI protected. Older Calgary homes rarely are. Typical fix: $30–$120 per device installed. See our GFCI safety guide.
11. Federal Pacific and overloaded panels
Undersized 60-amp services, double-tapped breakers, and panels with a known failure history. Any of these can hold up insurance or financing. Typical fix: $2,500–$4,500 for a panel and service upgrade.
12. DIY basement development wiring
Unpermitted basement suites and rec rooms are everywhere in Calgary. Junction boxes buried in drywall, undersized wire and missing smoke/CO alarms are the norm. Typical fix: $1,000–$8,000 depending on scope.
Heating, cooling and ventilation
13. Furnaces at end of life
Calgary furnaces run hard. Mid-efficiency units from the 1990s, cracked heat exchangers, and furnaces with no service history are frequent findings. Typical replacement: $5,000–$8,500 for a high-efficiency unit.
14. Bathroom fans venting into the attic
Warm moist air dumped into a −25°C attic condenses and frosts on the sheathing, then soaks the insulation during a chinook. One of the biggest hidden mould drivers in the city. Typical fix: $250–$800 per fan.
15. Blocked soffit vents and thin attic insulation
Insulation blown over the soffits kills attic ventilation and triggers ice damming. Many 1970s–1990s attics sit at R-20 to R-30 when current practice is R-50 or better. Typical fix: $1,800–$4,000 to top up and install baffles.
16. Missing or unbalanced HRV
Newer tight builds need a working heat recovery ventilator. We routinely find them disconnected, never balanced, or with filters that have never been cleaned. Typical fix: $200–$1,200.
Roof, envelope and climate damage
17. Hail-bruised shingles
Calgary is Canada's hail capital — the 2020 and 2024 storms alone caused billions in damage. Bruising isn't always obvious from the ground, and an insurance claim window can close before you find out. Our drone roof scan is included in every inspection. Typical replacement: $9,000–$20,000.
18. Ice damming and chinook freeze-thaw damage
Melt-refreeze cycles push water back under shingles and into soffits and wall cavities. Look for staining at exterior wall tops and rotted fascia. Typical fix: $500–$5,000 plus the ventilation correction that caused it.
19. Failed window seals and stucco cracking
Fogged thermal panes are near-universal in 1990s Calgary homes, and acrylic stucco from that era cracks at window corners, letting water into the wall assembly. Typical fix: $350–$900 per window; $1,500–$8,000 for stucco repairs.
20. Elevated radon
Calgary sits in a moderate-to-high radon zone, and Health Canada testing has found a meaningful share of homes above the 200 Bq/m³ guideline. It's invisible, and only a test tells you. Typical mitigation: $2,500–$3,500. More in our radon testing guide.
How to use this list as a buyer
Not every finding is a deal breaker. Sort them into three buckets: safety issues (electrical, heat exchanger, radon) that should be fixed regardless; big-ticket deferred maintenance (roof, furnace, repipe, sewer line) that belongs in your price negotiation; and normal maintenance you'll handle over time. A good inspection report prioritizes them for you so you can go into the condition-period conversation with numbers instead of anxiety.
Want to know what your own inspection will cost? Use the Calgary home inspection cost calculator for an instant estimate, or read the full Calgary inspection pricing breakdown. Ready to book? Schedule an inspection or call (403) 710-7770.