20×12 Deck Cost in Idaho
A 20×12 (240 sqft) deck in Idaho costs $15,360-$24,480 in mid-tier composite with the state's 1.28× labor multiplier (West). A 12×20 deck (240 sqft) is a long, narrow deck — common for ranch-style homes with a long back wall. Idaho labor 1.28× national, but materials roughly national average — labor is the variance driver.
5 finish tiers — 20×12 in Idaho
National $/sqft × Idaho's 1.28× labor multiplier × 240 sqft = total installed cost. Materials + labor + standard railing included.
Excludes permit ($218-$537 typical in Idaho), demolition (if replacing), and exceptional framing for 36″ frost depth. ID permits $150-280. Frost depth 36-42″ across most of the state.
20×12 framing notes for Idaho
Idaho considerations
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FAQ — 20×12 deck in Idaho
How much does a 20×12 deck cost in Idaho?▾
In Idaho, a 20×12 (240 sqft) deck costs $7,680-$12,240 in pressure-treated, $15,360-$24,480 in mid-range composite (Trex Transcend / Fiberon Sanctuary), and $23,040-$33,840 in luxury composite/PVC (TimberTech AZEK / Trex Signature). Numbers reflect Idaho's 1.28× labor multiplier on 2026-Q1 retail.
What's the cheapest way to build a 20×12 deck in Idaho?▾
Cheapest = ground-level pressure-treated pine with no railings (where exempt under 30″ height) — ~$6,144-$9,216 in Idaho. Add stairs + railings + above-grade framing and the build goes to ~$8,602-$12,288. DIY saves 30-50% on labor but requires permit + inspection coordination yourself.
How long does it take to build a 20×12 deck in Idaho?▾
Permit timeline in Idaho: 2-6 weeks depending on jurisdiction. Construction time for a 20×12: pro crew = 5-8 days for framing + boards + railings + stairs. DIY = 3-5 weekends for experienced DIYer. Allow extra time for permit approval + inspections.
What framing do I need for a 20×12 deck in Idaho?▾
IRC R507-compliant framing for a 20×12 deck typically uses 2×8 joists at 16″ OC for spans up to 12 ft, 2×10 joists for spans 12-16 ft. Idaho's frost depth is 36″ — footings must extend below that per IRC R403.1.4. Sonotube 10-12″ diameter at 36″ depth is typical. Verify with your local building department.
Is composite worth it for a 20×12 deck in Idaho?▾
Over 25 years in Idaho: PT pine = ~$9,216 install + ~$19,200 maintenance (stain every 2-3 yr) = $28,416 total. Mid composite = ~$17,818 install + $0 maintenance = $17,818 total. Composite wins by 59-81% over 25-yr lifecycle PLUS better resale value in Idaho's market.