How much does it cost to repair a section of rotting deck boards on a 10-year-old deck in Calgary?

Repairing rotting deck boards on a 10-year-old Calgary deck typically costs $8-15 per square foot for materials and labour, or $200-500 for a small section of 5-10 boards. The total cost depends on the extent of the damage, board type, and whether the underlying joists need repair as well.

For a typical repair involving 20-30 square feet of rotted boards, expect to pay $400-800 if only the deck boards need replacement. If the rot has spread to the joists underneath — common in Calgary due to chinook freeze-thaw cycling and moisture infiltration — costs can jump to $1,200-2,500 for structural repairs including temporary shoring, joist replacement, and proper flashing installation.

Calgary's climate accelerates deck rot in predictable patterns. Chinook winds create rapid freeze-thaw cycles that crack finishes and allow moisture to penetrate end grain and board joints. The areas most prone to rot on a 10-year-old deck are typically around stairs, near the house connection, and anywhere water pools or snow accumulates. If your deck hasn't been stained regularly (every 2-3 years), the UV exposure at Calgary's elevation has likely degraded the wood's natural moisture resistance.

Material costs for replacement boards run $3-8 per square foot depending on the species. Pressure-treated lumber is cheapest at $3-5/sqft, cedar runs $6-10/sqft, and if you're upgrading to composite to avoid future rot, expect $10-15/sqft for materials. Labour adds another $5-10/sqft for removal of old boards, inspection of substructure, and installation of new decking with proper fasteners and spacing.

The key question is whether the rot is isolated to surface boards or has spread to the structural framing. A qualified deck contractor can assess this by probing with an awl or screwdriver — soft, spongy wood indicates rot, while solid wood sounds sharp when tapped. If joists are compromised, they must be sistered (reinforced) or replaced entirely, which requires temporary support and significantly more labour.

Timing matters for deck repairs in Calgary. Plan repairs for late spring through early fall when temperatures are consistently above 10°C. If you're staining the entire deck after repairs, the new boards need 3-6 months to weather and dry before accepting stain properly. Many homeowners use this repair opportunity to upgrade to composite decking for the affected section, eliminating future rot concerns entirely.

Consider this an opportunity to address the root cause. Most deck rot in Calgary stems from inadequate drainage, missing or failed flashing, or lack of proper maintenance. While replacing boards, ensure proper ventilation underneath, check that flashing is intact where the deck meets the house, and plan a staining schedule to protect the remaining wood.

Need help finding a deck contractor to assess the damage and provide a repair estimate? Calgary Deck Contractors can match you with experienced professionals who understand how Calgary's climate affects deck longevity and can recommend the most cost-effective repair approach for your specific situation.

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Looking for experienced contractors? The Calgary Construction Network connects homeowners with qualified professionals:

• Ardco Construction
• Bracha Concrete & Coatings Inc.
• Venkor Group Inc
• Eshine Cleaning Services
• PLATINUM Pool & Spa Services Ltd