Deck Cost Calculator

PT Wood $8–$15 · Cedar $11–$20 · Redwood $12–$22 · Composite $15–$25 · PVC $18–$30 · Hardwood $20–$40 (installed per sq ft) · Railings, stairs & footings not included

Estimates based on 2026 US average pricing. Actual costs vary by region. Always get 3 quotes before starting.

Understanding the Calculator Inputs

This calculator estimates deck surface and framing cost based on four inputs. The output is a realistic range — not a single number — because deck pricing varies significantly by region, contractor, and site conditions. Here's what each input means and what the estimate does and does not include.

Deck Dimensions

Enter the outside dimensions of the finished deck surface. For L-shaped or irregular decks, calculate each rectangular section separately and add the costs together. The calculator covers the deck platform — the flat surface area you walk on. Stairs, railings, and any attached structures are priced separately.

Deck Material

Material is the biggest cost variable on a deck project — a 320 sq ft deck ranges from $2,560 in PT wood materials to $7,040 in hardwood materials. The right material depends on your budget, maintenance tolerance, climate, and how long you plan to own the home. See the full wood vs composite comparison below.

DIY vs Contractor

DIY removes the labor cost but deck building is a skilled project requiring knowledge of ledger attachment, joist sizing by span, footing installation, and local building codes. A deck built without a permit or with inadequate structural connections is a liability and a safety hazard. DIY is realistic for experienced builders — if you haven't built a deck before, a contractor is the safer choice for anything elevated more than 12 inches off grade.

What the Calculator Does NOT Include

• Footings and posts — concrete footings run $150–$600 each depending on depth and diameter. A typical deck needs 4–8 footings. Use our concrete footing calculator to estimate this separately.
• Railings — $20–$60 per linear foot installed. A 40 ft perimeter railing adds $800–$2,400.
• Stairs — $150–$400 per step installed. A standard 3-step stair costs $450–$1,200.
• Permit fees — $200–$500 in most jurisdictions for decks over 200 sq ft or 30" above grade.
• Ledger board attachment to house — requires flashing, lag bolts, and sometimes siding removal.

3 Real-World Deck Examples

Complete all-in cost breakdowns for three common deck builds — surface, framing, footings, railings, and stairs all itemized separately.

Example 1 — Small Ground-Level PT Deck (10×12 ft, DIY)

A simple freestanding ground-level deck off a back door. PT lumber throughout, no railings required (under 30" above grade), 4 footings.

Real-world note: A 10×12 ground-level deck is a realistic weekend DIY project for someone with basic carpentry experience. The most critical step: getting the ledger attached correctly to the house (or building it freestanding with proper footing placement). A deck that pulls away from the house is the most common structural failure — use proper lag bolts, flashing, and joist hangers at every connection.

Example 2 — Standard Elevated Composite Deck (16×20 ft, Contractor)

The most common residential deck project — 320 sq ft elevated deck (3 ft above grade), composite decking, railings on 3 sides, one stair section.

Real-world note: The calculator shows $4,800–$8,000 for a 320 sq ft composite deck — that's the surface and framing estimate. The all-in cost with footings, railings, stairs, and permit is $9,970–$17,150. This is the number to budget from. Contractors who quote $5,000–$6,000 for this project are either excluding major components or cutting corners on footing depth and railing systems.

Example 3 — Premium Hardwood Deck (20×24 ft, Ipe, Contractor)

A high-end outdoor living deck using Ipe hardwood — 480 sq ft, elevated 4 ft, cable railings, two stair sections.

Real-world note: Cable railing systems are the single most expensive add-on on any deck — $150–$250 per linear foot installed vs $25–$45 for composite railings. On a large deck with 88 LF of perimeter, that's $13,200–$22,000 in railings alone. If you want the cable railing look at lower cost, consider cable railing kits you install yourself ($40–$80/LF) vs contractor-installed turnbuckle systems.

Deck Cost by Material Type (2026)

Complete pricing comparison for all 6 decking materials — including lifespan, maintenance requirements, and DIY feasibility.

Common Deck Sizes & Costs

Surface and framing costs only — add 30–50% for footings, railings, stairs, and permit for all-in budget.

Surface + framing only. Add $2,000–$6,000 for footings (6 footings), $800–$2,400 for railings (40 LF), $600–$1,200 for stairs, $200–$500 for permit.

Hidden Costs Most Deck Estimates Miss

1. Concrete Footings

Every elevated deck needs concrete footings drilled below the frost line — $300–$600 per footing including labor. A standard 16×20 ft deck needs 6 footings = $1,800–$3,600 in footings alone. This is almost never included in a basic deck estimate. Use our concrete footing calculator to estimate this separately.

2. Ledger Board Attachment

Attaching an attached deck to your house requires removing siding, installing flashing, drilling through the rim joist, and installing lag bolts at precise spacing. If done incorrectly, water infiltrates the wall and rots the rim joist — a $2,000–$8,000 repair hidden behind the siding. Ledger attachment is where most deck failures start. It requires a specific sequence of materials and is not optional on any attached deck.

3. Railings

Railings are required by IRC for any deck surface more than 30 inches above grade. Cost: $20–$60/LF for wood or composite railings, $150–$250/LF for cable or glass systems. On a 320 sq ft deck with 40 LF of railing: $800–$2,400 for standard railing, $6,000–$10,000 for cable. This is always a separate line item from the deck surface estimate.

4. Stairs

Stairs cost $150–$400 per step installed. A standard 3-step stair section runs $450–$1,200. A full staircase from an elevated deck (8–10 steps) runs $1,200–$4,000. Most deck estimates show just the platform cost — ask every contractor whether stairs are included before comparing bids.

5. Decking Sealing and Ongoing Maintenance (Wood)

Wood decks require sealing or staining every 2–3 years. Professional deck sealing costs $1–$3 per sq ft. A 320 sq ft deck costs $320–$960 per application. Over 20 years, that's $2,100–$6,400 in maintenance costs not in the installation estimate — often more than the cost difference between PT wood and composite at the time of installation.

6. Decking Waste Factor

Decking boards are cut to fit, and cuts at angles or around obstacles produce waste. Standard waste factor is 10% for straight boards, 15% for diagonal installation. A 320 sq ft deck with 10% waste needs 352 sq ft of boards ordered. This is already built into contractor quotes but often missing from DIY material estimates — add 10% to your board quantity before pricing at the lumber yard.

Wood vs Composite — Full 20-Year Cost Comparison

The upfront cost difference between PT wood and composite looks significant. The 20-year total cost comparison tells a different story.

Over 20 years, a properly maintained PT wood deck often costs more than composite when maintenance is factored in — and looks significantly worse by year 15 unless consistently maintained. Composite is the better long-term value for most homeowners in the mid-range budget. PT wood makes sense for budget builds where you're not planning to own the home long-term or where you genuinely enjoy regular deck maintenance.

Common Deck Estimation Mistakes

Budgeting Only the Decking Surface

The most common mistake — budgeting $5,000 for a deck because "320 sq ft × $15/sq ft = $4,800" and being shocked when the contractor quote comes in at $12,000+. The decking surface is 40–60% of a complete deck project. Always budget footings, railings, stairs, and permit before calling contractors.

Skipping the Permit

Unpermitted decks are flagged at home sale inspections and can require removal or costly retrofitting. More importantly, permit inspections verify structural connections — ledger attachment, joist spacing, footing depth — that directly affect safety. A deck that collapses injures people and creates unlimited liability for the homeowner. Pull the permit. It costs $200–$500 and protects your investment.

Choosing the Cheapest Bid Without Comparing Scope

A $7,000 deck bid vs a $12,000 bid for the same deck may differ because one excludes footings, railings, and permit. Ask every contractor to itemize: decking material, framing, footings (number and depth), railings (LF and type), stairs (number of steps), and permit. Compare line by line — not total to total.

Using Undersized Joist Hardware

Every joist must be connected with a properly rated joist hanger — not toe-nailed. Deck ledger connections must use structural lag bolts at code-specified spacing, not regular wood screws. All hardware in contact with PT lumber must be hot-dipped galvanized or stainless steel — standard zinc-coated hardware corrodes within 2–3 years in PT lumber. Wrong hardware is invisible from above and creates structural failures that appear years later.

How We Estimate Costs

The Formula

Total Cost = Area (sq ft) × (Material $/sq ft + Labor $/sq ft)

Deck area is length multiplied by width. Material and labor cost per square foot are applied per the selected decking material. The calculator output covers the deck platform (surface boards + framing) — the components that scale directly with square footage. Footings, railings, stairs, and permit are fixed or linear-foot costs that don't scale with deck area and must be added separately.

Pricing Sources

Material cost ranges are derived from retail and wholesale supplier pricing for each decking material at Home Depot, Lowe's, and regional lumber yards across 8 US markets. Labor rates come from contractor bid data on HomeAdvisor and Angi for completed deck projects with clearly defined scope, cross-referenced with RSMeans residential construction unit cost data. Ranges represent the 20th to 80th percentile of real market pricing.

Frequently Asked Questions