Estimate your 2026 Seattle deck build — pressure-treated, cedar, composite (Trex / TimberTech), or PVC. Configure dimensions, height above grade, railing linear footage, stairs, and footing type and the calculator returns an itemized material + labor + footing breakdown. Decks over 30" above grade need an SDCI permit; the calculator flags the threshold automatically.
This is the tool version of our full 2026 Seattle deck cost guide, which walks through the price matrix by size and material tier, SDCI permit rules, and a pre-project checklist. Read the guide for planning; use the calculator below for your specific footprint.
Is this a new deck build or renovation of an existing deck?
Project Configuration
Enter deck dimensions and select materials
Total area: 0 sq ft
Additional Features
Add safety railing around perimeter
Add stairs to access deck
Select your deck configuration
Apply sealant to protect deck from weather
Your Estimate
Configure your project and click Calculate
Enter your project details to get started
How Our Deck Cost Calculator Works
Professional deck building estimates for Seattle and Pacific Northwest homes
Accurate Cost Estimation
Our deck cost calculator provides comprehensive estimates based on Seattle-area construction rates and material costs. The calculator
factors in deck size, material selection (pressure-treated lumber, cedar, composite, or exotic hardwoods), height and complexity, railing systems,
and foundation requirements. We use current 2026 pricing from local suppliers including Dunn Lumber, Compton Lumber, and Home Depot, with labor
rates reflecting Seattle's skilled carpenter wages of $55-75/hour. The calculator accounts for material waste factors (typically 10-15%), fastener
costs including structural screws and hidden fastening systems, and all structural components from posts and beams to joists and decking boards.
Ground-level decks, elevated decks, and multi-level designs each have different cost structures that our calculator precisely captures.
What The Calculator Includes
Every deck estimate includes complete material breakdowns: structural lumber for posts, beams, and joists; decking material calculated
by board footage with waste factor; railing systems including posts, balusters, and top rails; stair construction for elevated decks; all fasteners
and hardware; concrete footings and post brackets; and flashing/waterproofing materials. Labor costs encompass site preparation, post hole digging
and concrete work, framing and structural assembly, decking installation, railing construction, stair building, and final finishing. Our calculator
includes Seattle permit costs (typically $500-800 for residential decks) and inspection fees. For elevated decks over 30 inches, we factor in
additional structural requirements mandated by Washington State building codes. Material quality multipliers reflect price differences between
pressure-treated pine, Western Red Cedar, composite brands like Trex or TimberTech, and premium hardwoods like Ipe.
Seattle-Specific Considerations
Seattle's climate and building regulations significantly impact deck construction costs. The Pacific Northwest's high rainfall requires
proper drainage design, elevated joist spacing, and rot-resistant materials - our calculator defaults to these weather-appropriate specifications.
Seattle building codes require permits for most decks, engineered plans for structures over 200 square feet or more than 30 inches high, and
specific seismic fastening requirements for our earthquake zone. The calculator accounts for frost line depth requirements (typically 12-18 inches
in King County), which affects foundation costs. Many Seattle homes sit on slopes requiring additional structural support and engineering.
Western Red Cedar, harvested locally, offers an excellent middle ground between pressure-treated lumber and expensive composites, naturally
resisting decay in our wet climate. L&I regulations require licensed contractors for most deck projects, and our estimates reflect only
properly insured, bonded professionals who pull appropriate permits and meet all code requirements.
Using The Calculator Effectively
For accurate estimates, measure your intended deck area precisely in square feet. Specify the deck height from ground to deck surface -
this dramatically affects costs as elevated decks require stairs, additional structural support, and railings. Select your preferred decking material
based on budget and maintenance preferences: pressure-treated lumber offers the lowest upfront cost but requires annual maintenance; cedar provides
natural beauty and rot resistance at moderate cost; composite decking costs more initially but eliminates staining and sealing; exotic hardwoods
like Ipe offer unmatched durability and appearance at premium prices. Indicate if you need stairs, built-in benches, or planters as these add
to costs. Consider railing style carefully - cable railing systems cost more than traditional balusters but offer superior views. The calculator
provides instant feedback as you adjust specifications, helping you understand how material choices and size affect your budget. All estimates
include projected timeline, material quantities, and a detailed breakdown of foundation, framing, decking, and railing costs.
Frequently Asked Questions
How long does a deck last in Seattle's climate?
Pressure-treated lumber decks last 15-20 years with proper maintenance. Cedar decks can last 20-30 years when regularly sealed and maintained. Composite decking lasts 25-40 years with minimal maintenance. The Pacific Northwest's moisture requires diligent maintenance - unsealed wood decks deteriorate rapidly in our wet climate.
Do I need a permit for my Seattle deck?
Most decks require permits in Seattle. Any deck more than 30 inches above grade, attached to the house, or over 200 square feet needs a permit. Ground-level freestanding decks under 200 square feet may not require permits, but checking with Seattle DCI is always recommended. Permit costs typically run $500-800 and the review process takes 2-4 weeks.
What's the best decking material for Seattle weather?
For Seattle's climate, Western Red Cedar offers excellent natural rot resistance and weathers beautifully if maintained. Composite decking from brands like Trex provides worry-free durability without maintenance but costs 50-80% more than cedar. Pressure-treated lumber works but requires annual sealing. Avoid untreated pine or hardwoods not rated for ground contact as they'll rot quickly in our wet conditions.
Why Trust Our Calculator?
Our interior painting cost calculator is built by Kolmo Construction, a licensed general contractor (License #KOLMOC*852PL) serving Seattle since 2008. We've completed over 500 interior painting projects throughout King County, from single-room refreshes to whole-home transformations. Our estimates reflect real-world costs from actual projects, not theoretical calculations. We maintain relationships with major paint suppliers, understand Seattle's permit requirements intimately, and employ only licensed, insured professionals. Every estimate includes a detailed breakdown of materials and labor, showing you exactly where your money goes. We stand behind our estimates - when you request a formal quote, we honor the calculator's projections for projects matching the described conditions.
What this calculator captures
Total installed pricing for a common 16x20 footprint (~320 sq ft) with railings and one set of stairs. Scale roughly linearly with deck area.
Pressure-treated wood
$8,000-$14,000
Most affordable. Refinishing every 2-3 years. Best for rental properties or budget-sensitive projects.
Composite (Trex / TimberTech)
$18,000-$26,000
No refinishing, 25-year warranty. Common Seattle choice given the wet winters — low maintenance pays back within 5-7 years.
Multi-level + premium
$30,000+
Two-level layouts, built-in seating, pergola, cable or glass rail. Often paired with regrading or retaining wall on sloped Seattle lots.
Using this calculator
Does the estimate include the SDCI permit?
No — the calculator returns material and labor only. Decks over 30 inches above grade require an SDCI permit. Typical permit cost is $400-$900 depending on deck size and structural review. Use our Permit Assessment tool at /permit-assessment for your specific project.
How does the calculator handle tear-off of an existing deck?
Toggle 'existing deck removal' and the calculator adds $2-$4 per sq ft covering demo labor, hauling, and Seattle-area transfer station tipping fees. If you're keeping the existing framing and only replacing decking boards and railings, flag 'decking + railing only' to price just the surface layer.
Are railings priced separately or bundled?
Separate line item priced by linear foot and style. Pressure-treated wood runs $20-$35/ft, composite $35-$55/ft, cable or glass $60-$120/ft. The calculator asks for railing LF and style separately from deck area — project totals shift $3,000-$8,000 depending on choice.
Does it account for footings on Seattle clay soil?
Yes — footing dropdown offers concrete pier (standard), helical pile (fast, no excavation — good for wet Seattle winters), and ground screw (smallest footprint, most expensive). On Seattle's clay-heavy soil concrete piers typically reach 24-36 inches below grade. The calculator prices depth-appropriate footings.
Can I model a covered pergola or roof over the deck?
Pergola (open overhead slats) is a built-in-feature toggle adding roughly $3,000-$8,000 depending on span and material. A solid roof turns the project into covered-patio scope with different framing, rafter tie-ins, and a separate permit; the calculator doesn't fully price that. Contact us for a custom quote.
