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How to Build a Deck

Step-by-step deck building guide for Canadians. Footings, framing, decking, railings, and finishing. Permit requirements and cost breakdown.

Step-by-step deck building guide for Canadians. Footings, framing, decking, railings, and finishing. Permit requirements and cost breakdown.

Key Takeaways:

  • A DIY deck build takes 2-4 weekends for an experienced handyperson
  • Always get a building permit before starting - required for decks 24"+ above grade
  • Footings must extend below the frost line (4-6 feet in most of Canada)
  • Materials for a 300 sq ft PT wood deck cost approximately $2,500-$4,500
  • The ledger board connection to the house is the most critical structural detail - do this wrong and the deck can collapse

Step-by-Step Overview

Step 1: Design and Permits

Decide on size, shape, height, and material. Draw a site plan showing the deck's position relative to the house, property lines, and setbacks. Submit for a building permit ($200-$500, 2-6 weeks processing).

Step 2: Layout and Footings

Mark footing locations using batter boards and string lines. Dig below the frost line - 1.2-1.8m depending on your region. Install sono tubes or helical piles. Schedule footing inspection before pouring concrete.

Step 3: Posts and Beams

Set 6×6 pressure-treated posts in post brackets on footings. Level and plumb each post. Install doubled 2×8 or 2×10 beams on top of posts using through-bolts (not just nails).

Step 4: Ledger Board

The most critical step. The ledger board connects the deck to the house. It must be through-bolted to the rim joist with 1/2" lag screws or through-bolts at 16" on-centre. Install self-adhering flashing membrane behind and over the ledger to prevent water from entering the house wall. Failure at the ledger connection is the #1 cause of deck collapse in Canada.

Step 5: Joists

Hang joists from the ledger board and beam using Simpson Strong-Tie joist hangers (CSA A370 compliant). Standard spacing is 16" on-centre for wood boards or 12" on-centre for composite (check manufacturer specs). Install blocking between joists at 8-foot intervals for lateral stability.

Step 6: Decking

Install deck boards perpendicular to joists using appropriate fasteners. Leave 1/8" gap between boards for drainage and expansion. If using composite, follow manufacturer gapping instructions exactly - typically 3mm side gap and 6mm end gap.

Step 7: Railings and Stairs

Install code-compliant railings (42" height, 4" max baluster spacing). Build stairs with consistent rise (max 7.75") and run (min 10"). Schedule final inspection.

DIY vs Hiring a Contractor

Factor DIY Contractor
Cost (300 sq ft PT wood) $2,500-$4,500 materials $6,000-$12,000 total
Time 2-4 weekends 3-5 days
Quality Variable - depends on skill Consistent - experienced
Permit responsibility You pull the permit Usually contractor pulls
Warranty None Workmanship warranty
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