How much does it cost to build a deck in 2026?
The two tables above price this calculator’s 16 × 12 reference job (attached, 3 ft above grade, composite railing, stairs, permit): the first by decking board, the second by deck size. HomeGuide’s deck cost guide (February 10, 2026) puts a new pressure-treated deck attached to a one-story home at $25-$50 per square foot installed, about $3,600-$7,200 for 12 × 12 and $10,000-$20,000 for 20 × 20. HomeGuide’s figures describe average attached decks with no stated railing, stairs or permit; this calculator prices a specified job, and the two are not calibrated against each other.
For the 16 × 12 reference job, the chart What moves this price the most varies one input at a time across its tested range: there, the deck’s length and width move the modeled midpoint most, and the railing choice and the deck’s height move it more than the decking board does. At other sizes the order can change; see what drives project costs.
What drives deck cost
- Decking material — pressure-treated boards at $5-$8 per sq ft and hardwood at $12-$22 per sq ft, board material before markup.
- Deck height — taller decks need longer posts, more bracing and footings sized by the design (their depth follows local frost depth and soil). Model codes require a guard where the walking surface is more than 30 in above grade; this planner prices a railing from 30 in up, the conservative side of that line.
- Railing type — wood and composite railings, which this calculator prices the same, at $35-$60 per linear foot installed; glass at $235-$400 per linear foot.
- Stairs — $206-$350 per step installed. A 36 in deck needs 5 steps; a 60 in deck needs 8.
- Substructure — $11-$18 per sq ft installed for the joists, beams, posts and footings; complex shapes and steel framing run higher.
- Permit — this calculator allows $50-$300; the fee is set by your building department.
- Region — this calculator’s location factors put California and New York labor 30-35% above the national average.
Choosing the right decking material
Pressure-treated lumber (PT)
Pressure-treated boards: $5-$8 per sq ft. Cheapest, easiest to find, lasts 15-20 years with regular sealing or staining (typically every 1-3 years, depending on sun, weather and product). The default choice for most homeowners. Boards may warp, crack, or splinter over time.
Cedar
Cedar boards: $7-$12 per sq ft. Naturally rot-resistant and insect-repellent. Ages to a silver-gray; needs sealing if you want to keep the warm tone. Lasts 20-30 years.
Composite (Trex Enhance, TimberTech Edge)
Basic composite boards: $5-$9 per sq ft. Capped composite (wood fiber + plastic with a polymer shell). 25-year warranty typical. No sealing or staining; just rinse.
Composite premium (Trex Transcend, TimberTech Pro)
Premium composite boards: $8-$13 per sq ft. Higher-grain capped composite with multi-tone coloring. 30-50 year warranty. Looks closer to real wood than basic composite.
PVC (AZEK / TimberTech AZEK)
PVC boards: $9-$13 per sq ft. All-PVC boards (no wood at all). Lightest weight, fully waterproof, longest lifespan. No staining or rot. The most expensive mainstream option.
Hardwood (ipe, mahogany, garapa)
Hardwood boards: $12-$22 per sq ft. Tropical hardwoods with 50+ year lifespans. Beautiful grain. Needs annual oiling to keep color; otherwise grays. Extremely heavy and hard on tools.
Deck design fundamentals
Sizing
- 10x12 (120 sf) — small bistro / fire pit area for two.
- 12x16 (192 sf) — a common family size; fits a 6-person dining table plus a small seating area.
- 14x20 (280 sf) — comfortable dining + lounge zones.
- 16x20+ (320 sf+) — outdoor kitchen or hot tub possible.
Height
Most decks attach to a sliding door or doorway, putting them 12-36 in above grade. The IRC requires a guard where the walking surface is more than 30 in above grade, measured within 36 in horizontally of the open edge — more than 30 in, not 30 in exactly, and the measurement is taken to the grade below rather than to the next step down. A residential guard is 36 in tall (42 in commercial). This planner treats 30 in as the trigger, which is the conservative side of the model code; your adopted local code and its amendments are what actually govern. Well below the trigger, a guard is optional — many homeowners skip it for a more open look.
Stairs
Stairs are computed by deck height: at 7.5 in per riser, a 36 in deck needs 5 risers, a 60 in deck needs 8. The IRC max riser is 7.75 in, min tread depth is 10 in. Each step is priced at $206-$350 installed. Tall decks (60 in+) often add a landing partway down.
Footings
Concrete pier footings, often 12 inches across, go below the local frost depth: at least 12 in deep under the IRC, and deeper wherever the frost line is lower. In rocky soil or on slopes, helical-pier footings or stepped concrete piers add cost. Most decks need a footing every 6-8 ft along beams.
Deck replacement cost
Replacing an existing deck costs more than building new, because the old structure has to come out first. HomeGuide (February 10, 2026) puts deck replacement at $30-$55 per square foot installed, and a 20 × 20 replacement at $12,000-$22,000.
- Demolition & disposal — tear-out labor plus dump fees for treated lumber, which depend on the deck’s size and height and on local dump fees.
- Boards-only (resurface) — if the substructure is sound, replacing just the decking and railing on the existing frame is the cheapest way to refresh a deck.
- Full rebuild — if joists, beams, posts, or footings are rotted or out of code, budget for a complete teardown and rebuild at new-construction rates plus demolition.
This calculator prices a new build; it has no tear-out or disposal line, so get removal priced separately. A structural engineer or contractor should confirm whether your existing framing can be reused or must be replaced.
Frequently asked questions
How much does it cost to build a deck in 2026?
HomeGuide's deck cost guide (February 10, 2026) puts a new pressure-treated deck attached to a one-story home at $25-$50 per square foot installed, about $3,600-$7,200 for 12 by 12 ft and $10,000-$20,000 for 20 by 20 ft. In this calculator, the 16 by 12 ft reference job in pressure-treated boards (attached, 3 ft above grade, composite railing, stairs, permit) runs about $8,900-$15,400. A 20 by 14 ft attached deck of basic composite boards with aluminum railing, 3 ft above grade, stairs and permit runs about $12,800-$22,300. HomeGuide's figures describe average attached decks with no stated railing, stairs or permit; this calculator prices a specified job, and the two are not calibrated against each other.
Is composite or pressure-treated decking cheaper?
HomeGuide's deck cost guide (February 10, 2026) puts pressure-treated decks at $25-$50 per square foot installed and composite decks at $40-$80. In this calculator, switching the 16 by 12 ft reference job to basic composite boards, which also switches the face screws to the hidden-fastener line, adds about $220-$520. Composite needs no sealing or staining; pressure-treated boards do.
Do I need a permit to build a deck?
Usually yes. Permit thresholds are set by each jurisdiction rather than by the IRC, and commonly turn on height above grade, floor area, or attachment to the house, often around 30 in or 200 sq ft, but neither number is universal. This calculator's permit line is $50-$300. HomeGuide's deck cost guide (February 10, 2026) puts deck permits at $50-$150. Confirm the trigger and the fee with your local building department before you budget.
What size deck do I need?
12x12 (144 sf) fits a small bistro table for two. 12x16 (192 sf) is a common family deck size. 14x20 (280 sf) fits a dining table plus seating. 16x20+ (320 sf+) supports outdoor kitchens or multi-zone layouts.
How much does a Trex (composite) deck cost?
HomeGuide’s deck cost guide (February 10, 2026) puts composite decks at $40-$80 per square foot installed and Trex decks at $45-$70. In this calculator, basic composite boards (Trex Enhance or TimberTech Edge class) are $5-$9 per sq ft of board material, before markup. Premium composite boards (Trex Transcend or TimberTech Pro class) are $8-$13 per sq ft. The installed cost of each at the 16 × 12 reference job is in the “Deck cost by material” table above; select a composite material in the calculator to model your own deck.
How long does a deck take to build?
A 2-3 person crew typically builds a 200-300 sq ft deck in 4-7 days, depending on weather, footing complexity, and railing system. Composite installation is slower than PT due to hidden fasteners and tighter cuts.
What size joists and beams do I need?
For typical residential decks: 2x8 joists at 16 in O.C. (or 12 in O.C. for composite), 2x10 or 2x12 doubled beams, 6x6 PT posts. Always check the American Wood Council’s deck construction guide (DCA 6), which follows the IRC, or have a structural engineer review your plan for spans over 14 ft.
Can I build a deck myself (DIY)?
Yes for low decks under 30 in (no railing required) and under ~150 sf. Beyond that, the framing complexity, code requirements, and labor of moving lumber make a contractor a reasonable call.
What's the cheapest railing?
In this calculator, wood and composite railings tie at $35-$60 per linear foot installed. Aluminum railing is $47-$80 per linear foot. Cable railing is $118-$200. Glass railing is $235-$400. HomeGuide’s deck cost guide (February 10, 2026) puts wood or vinyl railing at $20-$60 per linear foot.
How long does a deck last?
PT: 15-20 years with maintenance. Cedar: 20-30 years. Composite: 25-50 years. PVC: 50+ years. Hardwood (ipe): 50+ years. The substructure (PT framing) typically outlasts whatever decking sits on it.
Why does the calculator show a price range?
Material and labor costs vary across regions, seasons, and contractors, and composite brands differ in price. The calculator adds up the low and high ends separately, from each line item’s low and high rate, so the range carries that spread instead of a single guess. Use the low end as best-case, the high end as a realistic ceiling.
