Terminology

• Ledger: member bolted or screwed to the building band joist that carries one side of the deck
• Band joist / rim joist: the building framing the ledger attaches to
• Beam, joist, post: framing members; posts bear on footings
• Decking: surface boards, solid wood or plastic composite
• Hold-down: connector that resists lateral and uplift loads
• Free-standing deck: deck supported by its own posts, not attached to the building
• Wet service factor: design reduction for wood exposed to moisture
• Flashing: corrosion-resistant metal or membrane that sheds water at the ledger
• Composite deck board: plastic or wood-plastic board tested to ASTM D7032

Standards

Test and listing standards

• ASTM D7032: plastic composite deck boards, stair treads, guards, and handrails
• ASTM E84 / UL 723: flame spread of composite decking
• FGIA 711: self-adhered flashing
• American Wood Council: DCA 6, prescriptive residential wood deck construction guide
• Code provisions are collected in the site elements code reference

Materials

• Pressure-treated softwood: lowest cost framing and decking
• Cedar and redwood: naturally durable decking
• Ipe and other dense tropical hardwoods: very durable and dense
• Wood-plastic composite and PVC: low-maintenance boards in many colors
• Fasteners and connectors: hot-dipped galvanized, mechanically galvanized, or stainless steel; stainless steel near salt water
• Flashing: corrosion-resistant metal or approved nonmetallic material

Detailing

• Flash the ledger and lap the water-resistive barrier over the flashing
• Fasten the ledger with the specified bolts or lag screws and never nail it, rely on toenails, or bear it on stone or masonry veneer
• Do not rely on soil for post lateral restraint in expansive or compressible soils
• Tie guards to the deck framing with a continuous load path; do not notch 4x4 guard posts
• Use hangers for side-mounted joists and blocking at joist ends
• Allow gaps between boards for drainage and expansion
• Keep framing off the ground and ventilated; protect cut ends of treated lumber
• Follow composite manufacturer's span, spacing, and gapping rules

Uses

Specific uses

• Residential decks and porches
• Rooftop and garden terraces
• Boardwalks and waterfront platforms
• Stair treads and landings

Pros and cons

Pros

• Quick to build with common framing
• Warm, natural look in wood
• Composite and PVC resist rot and need little maintenance

Cons

• Wood needs sealing and eventually replacement
• Composite can be hot and slippery and may stain
• Ledger and lateral connections are critical and must be inspected
• Decks near buildings are exposed to water and decay

Manufacturing and cost

Construction

• Pressure-treated or naturally durable framing set on footings and posts with a flashed ledger, beams, joists, and decking boards screwed or hidden-fastened to joists

Main manufacturers and suppliers

• Trex
• TimberTech
• Fiberon
• Deckorators

Trade association: American Wood Council.

Typical costs

• Composite deck, installed: about $25 to $60 per sq ft
• Wood deck, installed: about $20 to $35 per sq ft

Sources

• UpCodes: 2024 IRC Chapter 5 floors, Section R507 exterior decks, https://up.codes/viewer/general-services-administration/irc-2024/chapter/5/floors
• Advantage Lumber: price difference between composite and wood decking, https://blog.advantagelumber.com/2025/05/16/what-is-the-price-difference-between-composite-and-wood-decking/
• Bob Vila: composite decking vs wood cost, https://bobvila.com/articles/composite-decking-vs-wood-cost
• American Wood Council: DCA 6 deck guide, https://www.awc.org/