Almost always. Any deck attached to a house, taller than 30 inches, or larger than 200 sqft triggers a permit in most U.S. jurisdictions. Permit cost is usually $100 to $500. Skipping it can mean a tear-out order plus fines, and most homeowners insurance policies void coverage on unpermitted structures.

Ground-level decks under 300 sqft are doable for an intermediate DIYer with a weekend or two. Anything elevated over 4 feet, attached to the house with a ledger, or over 400 sqft gets into structural territory most homeowners should leave to a contractor. DIY saves roughly 55 to 65 percent on labor.

Deck Building Cost Calculator

Q: Is composite worth the extra money?

Over a 25-year horizon, yes. Composite costs 60 to 80 percent more upfront but eliminates staining, sealing, and board replacement. Pressure-treated runs around $0.35 per sqft per year in maintenance. Composite is closer to $0.05. If you plan to stay in the house 10 plus years, composite wins the math.

Enter deck size, material, elevation, and features (railings, stairs, permits). Get an installed cost range with DIY and contractor options.

Deck size

Length (ft)

Width (ft)

= 320 sqft

Average backyard deck is 250 to 400 sqft. Measure the footprint, not including stairs or landings.

Decking material

Pressure-treated

from $22/sqft

Cedar

from $30/sqft

Redwood

from $36/sqft

Composite (mid)

from $40/sqft

Composite (prem)

from $50/sqft

PVC (Azek)

from $52/sqft

Pressure-treated is the cheap workhorse. Composite and PVC cost more but skip the every-two-years stain routine. Trex Enhance is mid composite; Trex Transcend and TimberTech AZEK are premium.

Elevation

Ground (0-2 ft) Low (2-4 ft) Mid (5-8 ft) High (9 ft+)

Each step up in elevation adds longer posts, deeper footings, and sometimes stamped drawings. Mid and high elevations usually require a structural engineer.

Install

Contractor DIY

DIY drops price by roughly 65 percent. Budget two to four weekends for a 300 sqft ground-level build.

Include railings

Linear feet

Add up the sides where you need a railing. 300 sqft deck usually means 40-60 lf.

Railing material

Wood Composite Aluminum Glass / cable

Stairs

Number of steps

Step material

Wood Composite PVC

Count treads, not risers. A 3 ft deck usually needs 4 to 5 steps.

Advanced (permit, prep, demolition)

Add $200 permit fee Site prep ($2/sqft) Old deck removal ($4/sqft)

Installed cost range

Line item	Cost
Deck surface (boards + substructure)	-
— materials share (incl. 10% overage)	-
— labor share	-
Railings	-
Stairs	-
Permit	-
Site prep (grading, layout)	-
Old deck removal	-
Midpoint total	-
Display range (-12% to +20%)	-

This is a planning estimate, not a quote. Labor swings wildly by zip code. A Texas crew might build a 320 sqft composite deck for $14k. Same deck in the Bay Area quotes $26k. Use this range to sanity-check real quotes. Excluded from the total: sales tax, general-contractor markup (13-22%), hazardous-material disposal, and architect or engineering fees if your build needs them.

Cost -

What this calculator gets right

Most deck cost tools online are lead-gen traps. You type in your zip code, they hand you off to three contractors, and the auto-dialer starts the next morning. The Trex and TimberTech calculators go a step further: they email-gate your result and only quote their own brand.

This one is different. Pick your material, size, and features. See the real installed cost range instantly. No email, no phone, no "a local pro will reach out shortly." The formula pulls from Homewyse's line-item database, Fixr's 2025 tables, Decks.com, and the specific per-foot ranges published by Trex, TimberTech, and Azek themselves. I cross-checked three test cases against real contractor quotes I got for my own backyard last spring.

Read the full deck cost guide for the math, or skim the FAQ for the 15 questions I get asked most.

Common questions

How much does a deck cost?

Installed deck cost runs roughly $22 per square foot for pressure-treated pine up to $52 for PVC. The national average for a 300 sqft deck is $8,000 to $12,500 installed by a contractor. DIY drops that to around $3,000 to $5,500 in materials if you already own the tools. My own 280 sqft ground-level PT deck ran $3,800 in 2020; the contractor quote was $9,200 for the exact same thing.

Is composite worth the extra money?

Over 25 years, yes. Composite costs 60 to 80 percent more upfront than pressure-treated but eliminates staining, sealing, and board replacement. PT needs $0.30 to $0.40 per sqft per year in maintenance. Composite runs closer to $0.05. If you plan to stay in the house 10 plus years, the math tilts to composite. If you're flipping in three years, PT still wins on total cost.

Do I need a permit?

Almost always. Any deck attached to a house, taller than 30 inches, or larger than 200 sqft triggers a permit in most U.S. cities. Permit cost is $100 to $500. Skipping the permit risks a tear-out order plus fines, and most homeowners insurance voids coverage on unpermitted structures. Call your county building department before you start. The permit process usually takes one to three weeks.

Can I DIY a deck?

Ground-level decks under 300 sqft are doable for an intermediate DIYer over a weekend or two. Anything elevated over 4 feet, attached to a house with a ledger board, or larger than 400 sqft gets into structural engineering territory that most homeowners should leave to a contractor. DIY saves about 65 percent on the total cost. My first DIY was a 280 sqft ground-level PT deck in 2020 and it took three weekends, one trip back to Home Depot for shorter joist hangers, and one Memorial Day cookout deadline I barely made.

See the full FAQ →