Straight (parallel) 20×12 Deck Cost
A straight (parallel) board pattern on a 20×12 (240 sqft) deck costs $12,000-$19,200 in mid-tier composite — 0% over straight. Straight parallel boards running perpendicular to the joists. The default, fastest, lowest-waste pattern — used on 78% of US residential decks per Houzz data.
5 finish tiers — straight (parallel) 20×12
National $/sqft × straight (parallel) pattern's 1.00× complexity × 240 sqft = total installed cost. 7% waste factor already applied to the material side. Multiply by your state's labor multiplier for a local figure.
What changes vs a straight 20×12
When to pick straight (parallel)
DIY builders, tight budgets, narrow decks, traditional architecture, fast permit + build paths.
Visually plainest pattern unless dressed up with a picture-frame border or contrasting color decking.
See this pattern in 3D before you commit
The Pattern Visualizer animation renders all 5 patterns live so you can rotate and compare. Useful for spousal sign-off and contractor conversations.
FAQ — straight (parallel) 20×12
How much does a straight (parallel) 20×12 deck cost in 2026?▾
A straight (parallel) pattern on a 20×12 (240 sqft) deck costs $6,000-$9,600 in pressure-treated, $12,000-$19,200 in mid-tier composite, $18,000-$26,400 in luxury composite/PVC. That's 0% over straight-pattern baseline — about $0 extra at mid composite.
What's the waste factor on a straight (parallel) pattern?▾
7% — vs 7% for straight boards. On a 20×12 deck that means ordering 396 linear feet of decking (vs 396 for straight). The extra 0 lf is the difference between order quantity and installed quantity, ending up as offcuts and short pieces.
Does a straight (parallel) pattern affect joist spacing?▾
Not necessarily — straight (parallel) works at standard 16″ O.C. joist spacing. Some specialty installs (diagonal-on-top variant) may step down to 12″.
Will my deck warranty cover straight (parallel)?▾
Every brand warrants straight installation. No spec deviation. 16″ O.C. joist spacing covers all dimensional lumber and composite.
Is straight (parallel) the right pattern for a 20×12 deck?▾
Best for: DIY builders, tight budgets, narrow decks, traditional architecture, fast permit + build paths. Watch-outs: Visually plainest pattern unless dressed up with a picture-frame border or contrasting color decking. At 240 sqft, straight (parallel) is well-balanced — fits the typical sweet spot for this pattern.