How much does a 16×20 deck cost?

A 16×20 ft (320 sq ft) ground-level deck costs about $8,600 installed in pressure-treated lumber at 2026 national averages — roughly $27 per sq ft. In cedar budget $11,200–$17,600, and in composite $14,400–$24,000. Height, stairs and design complexity move all three figures.

Is it cheaper to build a deck or a patio?

On a flat lot at ground level, a poured concrete or paver patio is usually cheaper per square foot than a deck. The deck wins when the ground slopes, the door sits well above grade, or you want to avoid excavation — the comparison flips as soon as a patio needs retaining walls or extensive grading.

Do I need a permit to build a deck?

Usually, yes. Most jurisdictions require a permit for attached decks of any size and for detached decks above a small area or height threshold (often 200 sq ft or 30 in off the ground). The permit covers footing depth, ledger attachment and railing height — the three things that make decks fail — and an unpermitted deck can complicate a future home sale.

How long does a deck last?

A pressure-treated frame typically lasts 25–40 years; the surface boards are the wear item — 15–25 years for wood boards kept sealed, 25–30+ years for composite and PVC. The frame almost always outlives the surface, which is why re-decking an existing sound frame costs far less than a new build.

Can I put a hot tub on a deck?

Not on a standard deck. A filled hot tub with occupants can weigh 3,000–5,000 lb concentrated on a small footprint, far beyond the 40–50 lb per sq ft a residential deck is designed for. It needs additional footings, beams and joists designed for the load — tell the builder before the design stage, not after.

What is the cheapest deck material that still lasts?

Pressure-treated pine, kept sealed. Its installed cost is roughly half of composite, and with stain or sealer every one to two years the boards last 15–25 years. The trade is your time: if you will not do the maintenance, composite is cheaper over twenty years even at double the build cost.

Deck Build Cost (2026) — National Average, Breakdown & What's Included

What it costs, and why the range is wide

Most homeowners pay between $4,200 and $17,500 for a professionally built deck in 2026, with a typical ground-level deck landing near $8,600. The spread is not mostly about size — it is about the decking material and how far off the ground the structure sits. The frame, footings and labour are broadly the same whether the surface boards are inexpensive pressure-treated pine or premium composite; the boards themselves, and the fasteners they need, are where the money moves.

As a planning rule, budget $25–$40 per sq ft installed for pressure-treated lumber, $35–$55 for cedar, and $45–$75 for composite. A second storey deck, a sloped site, or a design with diagonal boards, picture-frame borders and multiple levels pushes past the top of those ranges quickly, because every one of those choices adds framing labour rather than just material. Ground-level decks on flat lots with a simple rectangular plan sit at the bottom of the range — which is exactly why the typical project costed here is one.

One warning before the breakdown: the cheapest quote on a deck is often cheap because the footings are shallow, the joists are spaced at the maximum the code allows rather than what the board manufacturer recommends, or the ledger board is not properly flashed against the house. Those are invisible the day the deck is finished and expensive the day they fail.

Cost breakdown: where the money goes

For the typical 320 sq ft pressure-treated deck, a contractor's $8,600 quote usually builds up like this:

Line item	Materials	Labour	Total
Footings & concreteDug or augered holes below frost depth, poured concrete, post bases	$450	$550	$1,000
Framing lumber & beamsLedger, beams, joists, blocking and posts	$1,100	$900	$2,000
Decking boardsPressure-treated boards, laid straight with a waste allowance	$1,300	$1,100	$2,400
Railing & balustersThree sides, code-height rail with balusters	$650	$550	$1,200
StepsOne set of steps with stringers and treads	$350	$400	$750
Hardware, fasteners & flashingJoist hangers, structural screws, ledger flashing	$400	$150	$550
Permits, plans & disposalBuilding permit, simple plan set, offcut and packaging disposal	$450	$250	$700
Total for the typical deck320 sq ft at about $27 per sq ft installed	$4,700	$3,900	$8,600

Materials and labour are split the way contractors build a quote, so you can compare a real bid line by line. Figures are for the typical project above and will move with your spec — the next sections explain what moves them.

Cost by decking material

The frame does not change when the surface does — but the boards, fasteners and maintenance profile change completely. For the same 320 sq ft deck:

Decking material	Per sq ft installed	320 sq ft deck	Notes
Pressure-treated pine	$25–$40	$8,000–$12,800	Cheapest to build; needs sealing or staining every 1–2 years
Cedar	$35–$55	$11,200–$17,600	Naturally rot-resistant, softer underfoot; greys if left unfinished
Composite	$45–$75	$14,400–$24,000	Low maintenance; needs 12 in joist spacing on many products and hidden fasteners
PVC / capped polymer	$50–$80	$16,000–$25,600	Lightest and most stain-resistant; the highest material cost of the four
Tropical hardwood (ipe)	$55–$90	$17,600–$28,800	Extremely durable and heavy; pre-drilling every hole adds labour

Run your own board, joist and screw counts with the Deck Calculator before you compare quotes — a composite quote that assumes 16 in joist spacing on a board that requires 12 in is a quote for a deck that will feel spongy and may not be warranted.

What a standard quote includes — and what it leaves out

Usually included

Footings dug and poured to local frost depth
Framing, decking, standard railing and one set of steps
Structural hardware, hangers and ledger flashing
Building permit and inspections (in most contracts)
Site cleanup and disposal of offcuts and packaging

Commonly billed as extras

Demolition and removal of an existing deck ($500–$1,500)
Electrical work — outlets, lighting, a hot-tub circuit
Built-in benches, planters, pergolas and privacy screens
Staining, sealing or painting after the build
Landscaping repair, sod or a new path at the bottom of the steps
Engineering fees where the soil or design requires them

DIY or hire a pro?

Decks are the most DIY-able project in this guide series, and the saving is real: materials for the typical deck above are about $4,700, so a competent DIY build keeps most of the $3,900 labour line in your pocket. A ground-level rectangular deck is a long weekend-to-two-weekends project for two people with a circular saw, a drill/driver and a rented auger.

Be honest about the parts that are not forgiving. Footings must reach below the frost line or the deck heaves. The ledger board connection to the house is the single most common point of deck failure — it needs the right structural screws or through-bolts and continuous flashing, not nails into siding. And most jurisdictions require a permit and inspections for any attached deck and many detached ones, whether a contractor builds it or you do. If your design is elevated more than about 30 in off the ground, has a hot tub going on it, or attaches to a cantilevered floor, hire the structure out even if you lay the boards yourself.

Honest difficulty rating: Moderate for a ground-level rectangle; high for elevated, multi-level or hot-tub decks.

What drives the cost up or down

Height off the ground. A deck 6 ft up needs taller posts, more bracing, longer stairs and often engineered plans. Height adds labour faster than area does.
Decking material. Composite and PVC boards cost two to three times pressure-treated pine per foot, and hidden-fastener systems add hardware and time on every board.
Joist spacing the material demands. Many composite boards require 12 in spacing instead of 16 in — that is a third more joists, hangers and screws in the frame.
Site access and slope. A sloped lot means stepped footings and longer posts; a tight side yard means every board is carried, not dropped by a truck.
Design complexity. Diagonal laying patterns, picture-frame borders, curves and multiple levels all convert cheap boards into expensive labour.
Local labour rates and permit rules. Labour is roughly 45% of the typical quote, so a high-cost metro can move the total 25% or more on its own.

How to keep the cost down

Keep the rectangle. A simple rectangular plan at a stock lumber length (16 or 20 ft) avoids both cuts and the labour they cost.
Price the whole life, not the build: pressure-treated is cheapest to install but asks for stain every year or two; composite reverses that.
Get the footing and framing spec in writing — depth, joist spacing, ledger fasteners — before you compare prices, so quotes are for the same structure.
Build in late autumn or winter where the climate allows; deck contractors discount in their off-season.
If budget is tight, shrink the footprint rather than the spec. A smaller well-built deck beats a large spongy one, and decks can be extended later.
Use the Deck Calculator to build your own materials list, then ask suppliers for a package price — lumber yards discount full-project lists.

Frequently asked questions

Run your own numbers

These calculators use the same quantities a contractor prices from — measure your project and compare the materials side of any quote against your own figures.