Deck construction materials
- Pressure-treated lumber: lowest cost; needs periodic cleaning and sealing.
- Cedar and redwood: naturally rot-resistant, attractive; more maintenance and cost.
- Composite and PVC: higher upfront cost, low maintenance; follow the maker's joist-spacing and gapping rules.
The framing underneath is almost always pressure-treated lumber rated for ground contact where required.
Deck construction framing: footings, beams and joist spans
Loads travel from deck boards to joists, to beams, to posts, to footings below frost depth. Joist and beam sizes must come from span tables in your local code (for example, IRC Section R507) or from an engineer — they depend on species, grade, spacing and loads. Our deck calculator counts boards and joists; use the concrete calculator for footings.
Stairs and guards
The IRC sets a maximum riser of 7¾ in and a minimum tread of 10 in (R311.7.5), and guards are generally required where the walking surface is more than 30 in above grade (R312). Your local code may differ — NYC enforces its own building code. Plan stairs with the stair calculator.
Ledger attachment and flashing
Attached decks hang from a ledger board bolted to the house's band joist. Improper ledger attachment and missing flashing are leading causes of deck failures and hidden rot. Codes specify fasteners and flashing; never nail a ledger or attach it through siding without proper flashing.
Deck Construction costs in 2026
Installed cost per square foot of deck.
| Item | Typical range |
|---|---|
| Deck (typical range) | $30–$60 per sq ft; average ≈ $35 |
| Composite deck | ≈ $73 per sq ft |
| Basic professionally built deck | $25–$60 per sq ft (premium $40–$80) |
Typical national ranges. New York City and other high-cost metros often run above them — get several written bids for your project.
Calculators for this project
New York rules and permits
NYC. Decks generally require permits, filed through DOB NOW; confirm the requirements for your specific project, especially for decks on roofs or above the first floor. Contractors need a DCWP Home Improvement Contractor license.
Rest of New York. Footings must reach the local frost depth from your municipality's Table R301.2, and most towns require a building permit for attached or raised decks.
Frequently asked questions
How much does it cost to build a deck?
Decks typically cost $30–$60 per sq ft with an average around $35; composite decks often run about $73 per sq ft.
How far can deck joists span?
It depends on lumber size, species, grade, spacing and loads — use your local code's span tables or an engineer.
Do I need a permit for deck construction?
Usually, yes, for attached or raised decks. In NYC filings go through DOB NOW.
How deep do deck footings go?
Below the local frost depth set by your jurisdiction.
