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Cost guide

Deck Building Cost

Building a new attached or freestanding wood or composite deck with railing and stairs.

Typical range
$5,000–$25,000
Most people pay
$12,000
Service life
15–20 years for pressure-treated wood; 25–30 for composite

National cost range

National range, per deck, ~300 sq ft

$5,000 – $25,000

Most homeowners pay around $12,000. The spread is real, not hedging — the drivers below determine which end of it you land on.

Low end
$5,000
Simple access, like-for-like
Typical
$12,000
What most jobs come in at
High end
$25,000
Upgrades, difficult access, code work

What you are actually paying for

Find the row that matches your situation. Quotes that differ wildly from each other usually differ in scope, not in price.

ScenarioTypical cost
12×16 ground-level, pressure-treatedNo railing required under 30 inches.$4,000–$8,000
12×16 raised, wood, with stairs and railingThe most common attached residential deck.$8,000–$14,000
14×20 composite deck with railingComposite decking and railing at premium pricing.$12,000–$22,000
Multi-level deck with built-in seatingCustom design with multiple elevations.$15,000–$30,000
Freestanding deck, 16×20No ledger attachment; independent footings all around.$10,000–$18,000

What moves the price

In descending order of impact. These are also the questions worth asking a contractor whose quote sits outside the range above.

  1. Size and height

    A 12×16 foot ground-level deck is the baseline. A raised deck with stairs and railing costs more per square foot. Multi-level designs add complexity.

  2. Decking material

    Pressure-treated wood is cheapest at $15 to $25 per square foot installed. Composite runs $30 to $50. PVC and exotic hardwoods cost more.

  3. Foundation type

    Ground-level decks on concrete blocks are cheapest. Raised decks need poured footings below the frost line — $100 to $300 per footing.

  4. Railing and stairs

    Code requires railing on decks over 30 inches high. Cable, glass, and composite railing systems cost more than wood pickets.

  5. Ledger attachment

    An attached deck requires proper ledger flashing and bolt pattern per IRC R507. Improper attachment is the leading cause of deck collapse.

Can you do it yourself?

Limited DIY scope

An experienced DIYer can build a ground-level deck. Raised decks with proper footing depth, ledger flashing, and code-compliant railing require structural knowledge. Permits and inspections are required. Ledger attachment mistakes cause collapses.

Permits and inspection

A building permit is required for decks over 30 inches high or attached to the house in virtually every jurisdiction. Footing depth, ledger attachment, and railing height are inspected.
Run the DIY vs. pro decisionCheck a quote you already have

When this cannot wait

  • Replacing a deck with structural deficiencies — do not delay
  • Building season timing — contractors book months ahead in spring

Common questions

How much does it cost to build a 12x12 deck?
A 12×12 pressure-treated wood deck at ground level runs $3,500 to $7,000. Raised with railing and stairs: $6,000 to $12,000. Composite decking adds 50 to 100% to material cost.
How much does a deck cost per square foot?
Pressure-treated wood decks run $25 to $45 per square foot installed. Composite decks run $40 to $70. Ground-level decks cost less per foot than raised decks with footings and railing.
Do I need a permit to build a deck?
Yes, for any deck attached to the house or over 30 inches above grade in most jurisdictions. The permit covers footing depth, ledger attachment, railing height, and stair geometry.
Is composite decking worth the extra cost?
Composite costs 2 to 3 times more than pressure-treated wood but requires no staining or sealing and lasts 25 to 30 years. Worth it if you plan to stay 10+ years. Wood is cheaper if you are willing to maintain it annually.
Deck railing broke — fall hazard, repair or rebuild cost?
Railing section replacement runs $300 to $800. If posts are rotted at the base, partial rebuild runs $2,000 to $5,000. A deck over 15 years old with rotted railing posts often needs full rebuild at $6,000 to $12,000 for a raised deck.
Deck boards rotting and soft underfoot — replace cost?
Replacing deck boards only runs $1,500 to $3,500 for a 12×12 deck if the framing is sound. If joists are rotted, full rebuild runs $6,000 to $12,000. Walk the deck with a screwdriver — soft joists mean rebuild, not resurfacing.
Deck pulling away from the house — ledger board repair cost?
Ledger board failure is a collapse risk. Repair runs $1,000 to $3,000 including proper flashing and lag bolts. Full deck rebuild with correct ledger attachment runs $6,000 to $12,000. Do not use a deck with a separating ledger — it can fail under load.
Need a deck built before summer — how fast and how much for 12x12?
A 12×12 ground-level pressure-treated deck runs $3,500 to $7,000 and takes 3 to 7 days. A raised deck with stairs and railing runs $6,000 to $12,000 and takes 1 to 2 weeks. Book in early spring — summer scheduling adds 2 to 4 weeks wait.
Old deck not up to code — must rebuild for inspection, what does it cost?
Code upgrades on an existing deck (railing height, baluster spacing, stair geometry) run $1,000 to $3,000. If the structure itself is non-compliant, full rebuild runs $6,000 to $12,000. Failed inspection blocks sale or rental — budget for compliance before listing.
Composite deck vs. wood — cost difference for 12x12?
Pressure-treated wood: $3,500 to $7,000. Composite: $5,250 to $10,500 (50 to 100% more). Composite eliminates annual staining ($200 to $400 per year) and lasts 25 to 30 years versus 15 for wood. Break-even on maintenance: 8 to 12 years.

Decide what to do next

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