Cost to Build a Deck: Price Your Own Material List, Not a National Average

Every page on the cost to build a deck opens with a national average, and every one of them is an average of decks that are not yours. This guide does the opposite. It gives you the cost to build a deck as a material list for four standard sizes, priced shelf by shelf, so you can see what a deck is made of and price the same list at your own lumber yard. Installed costs, which add labor, come from the cost sites that publish them, named and dated.

We are not a contractor and we do not quote labor. Where a figure is ours, it comes from our designer. Where it is someone else’s, we name the source and the date.

What Sets the Cost to Build a Deck

Four things move the bill: how big the deck is, how high it sits, what you lay on top and how it meets the house. Only the last one is a surprise to most people.

Size and shape

Square footage drives the decking and the joists, but the framing does not grow in a straight line. The DCA6¹ guide limits the length out from the house to the width along it, so a deck grows along the wall first. Going from our 12x12 to our 12x16 adds a third post and a fifth footing, which is why the cost per square foot falls as the deck gets bigger.

Height above the ground

Height is where cost hides. The post table in the DCA6¹ guide caps a 6x6 post at a height set by the beam span and the joist span, so a high deck needs a shorter span or a bigger post. Once the deck is more than 30 in off the ground it also needs a guard, and the guard brings posts, hold-downs and balusters with it. A deck at 36 in, as in all four of our presets, already carries that cost.

Decking material

Wood decking is the cheap line and composite is the dear one. Composite also needs hidden clips and a joist spacing the maker sets, commonly 16 in, the same as treated 5/4 boards under the 2021 residential code. Pick the board before you price anything: in our four presets the composite list costs 19% to 28% more than the wood one.

Attached or freestanding

An attached deck hangs from a ledger on the house. A freestanding deck stands on its own, so it needs posts and a beam on the house side as well, and that is more concrete and more hardware. Attaching also adds flashing and the ledger bolts. Neither choice is free, and the right one is whichever your wall and your building department allow.

Cost to Build a Deck Per Square Foot, Wood vs Composite

Cost per square foot is the number everyone quotes and almost nobody defines. Here are two versions of it, ours and theirs.

Our materials per square foot

These are material lists from our designer at 36 in above grade, attached to the house, with stairs and guards on. Prices are Home Depot, Hamilton Mill store, shelf prices read between September 30 and November 4, 2026. Your store will differ.

Two things stand out. The per square foot cost falls by about a third from the smallest deck to the largest, because the stairs, the guard posts, the post bases and the ledger hardware do not scale with the area. And the decking alone is about $2 per sq ft in wood and $4.60 to $4.90 in composite, so most of the $11 to $22 is not the surface.

What the cost sites publish

Installed costs include the labor and the contractor’s margin, and the sites do not agree. Fixr, in a page dated January 2023, gives $15 to $25 per sq ft installed for pressure-treated wood and $28 to $40 for composite. HomeGuide, as of November 2026, lists $25 to $50 for wood and $40 to $80 for composite, substructure included. Trex, a decking maker, puts materials alone at $3 to $6 per sq ft for treated wood and $5 to $14 for composite, with no page date.

Those are three sources and three different decks. Do not average them. Read each as a statement about a deck we cannot see.

Why the ranges disagree

A contractor’s per square foot figure bundles everything: footings, framing, stairs, a guard, permit work, margin and the cost of the local labor market. A page that skips the guard and the stairs will land far below one that includes them. Our 12x12 materials alone come to $2,129, which is just under the bottom of Fixr’s installed range for the same area. That suggests its figure prices a simpler deck than ours, though we cannot see what is inside it.

Where the Money Goes in a Deck

The decking is not where the money goes. Split a 12x12 material list into groups and the surface is the smallest of the big ones.

Framing

Joists, the ledger, the beam and the posts come to $417 on the 12x12, about a fifth of the total. That is 12 joists of 2x8 at 12 ft ($236), four 2x12 beam boards ($146) and a 6x6 post ($36). The sizes come from the DCA6¹ tables, not from a rule of thumb, so they stay the same whether the deck is wood or composite.

Decking

Decking is $290 in wood and $676 in composite on the 12x12, which is 14% and 26% of the total. That is 26 boards of 5/4x6 at 12 ft, $10.28 each, or the same 26 composite boards at about $23.99 each. The composite price for 10 and 12 ft boards is an estimate, because the store did not list that length: price it at your yard.

Footings and concrete

The four footings cost $235, 24 bags of 80 lb mix at $6.47 and four 12 in tube forms at $19.98. That is 11% of the total, so the footing guide matters more for safety than for cost. See deck footings for how deep and how wide they go.

Hardware

Hardware is the biggest group on the 12x12, at $700, or 33% of a wood deck. It includes two 6x6 post bases at $59.42 each, joist hangers, lag screws, hold-down devices for lateral loads, hurricane ties, stringer connectors, deck screws, and the guard post hold-downs ($176) and through-bolts ($121). The same list with composite adds hidden clips and reaches $810.

Guards and stairs

The guard and stair group is $487 on the 12x12: stair stringers and treads, rail lumber, 4x4 posts and six packs of 2x2 balusters at $39.69 each. The hold-downs that tie the guard posts down are counted in the hardware group above. A guard is required above 30 in, so a low deck saves this group in whole or part. Our deck stairs guide covers the stairs themselves.

DIY or Contractor: What Labor Adds

A deck you build yourself costs the material list. A deck someone else builds costs the list, their labor and their margin, and that is where the national averages come from.

What published sources say about labor

Fixr lists labor at $10 to $35 per sq ft, depending on the material (January 2023). HomeAdvisor lists $15 to $35, and HomeGuide $11 to $22 for wood and $24 to $48 for composite, all as of November 2026. On a 144 sq ft deck, that is a sum anyone can do: Fixr’s range gives $1,440 to $5,040, HomeGuide’s wood range $1,584 to $3,168 and its composite range $3,456 to $6,912.

Installed totals by the same sources

Put the material list and those labor ranges next to each other and you get the installed picture. On 144 sq ft, Fixr’s installed rates give $2,160 to $3,600 for treated wood and $4,032 to $5,760 for composite. HomeGuide’s give $3,600 to $7,200 and $5,760 to $11,520. These are the sources’ own per square foot rates multiplied by the area, not a quote from us.

How to read a contractor’s bid

Ask for materials and labor as separate lines, then hold the materials line up against a list like ours. A materials line far above the list may include a margin or a better board, which is fine, but you should know which. A bid that does not say whether it includes the guard, the stairs, the footings and the permit is not comparable to another.

What our totals leave out

Our lists are floors. One line, the structural screws at the rim, has no shelf price and is left out. On the 10x10 and 12x16 the special-order 6x6 post caps are left out too. Tax, delivery, tools, a dumpster, stain or sealer and the permit are not in them either. Add them before you call it a budget.

Permit and Drawing Costs

A permit is a small line next to the lumber, but it can decide how long the job takes.

The permit fee

Fixr lists a deck permit at $100 to $500 depending on the area (January 2023), and the real fee is whatever your building department charges. Some offices charge by the value of the work, others a flat fee. The only way to know is to ask. For the rules on when you need one at all, read deck permit requirements.

Drawings

Many offices ask for a plan with the framing sized, the footings shown and the connections called out. That is the work of a drawing set, and doing it by hand or paying a drafter is a cost of its own. Our deck drawings for permit guide lists what a reviewer looks for, shows sample sheets and says what you have to supply yourself.

The cost of getting it wrong

A deck built without a permit where one is needed can be ordered opened up or removed, and that costs more than every other line in this guide. We do not state a figure, because it is local, so ask before you buy lumber.

Example Deck Sizes to Price

Each size below has a plan page with the full material list, the framing sizes and the 3D model. The numbers are the ones in the table above.

Small decks: 10x10 and 12x12

The 10x10 deck plans list $1,813 in wood and $2,160 in composite. The 12x12 deck plans list $2,129 and $2,625. Both stand on four footings and two posts, and both carry guards and stairs because the deck is 36 in up. Small decks are the most expensive per square foot, since the fixed items spread over fewer boards.

Larger decks: 12x16 and 16x20

The 12x16 deck plans list $2,472 in wood and $3,095 in composite, with five footings and three posts. The 16x20 deck plans list $3,643 and $4,654. The composite premium grows with the size, from 19% on the 10x10 to 28% on the 16x20, because the decking is the one line that grows with the area.

Any other size

For a 14x20, a 12x24 or an odd shape, use the deck material calculator. It counts the boards and prices them live, and switches between wood and composite. Take the list to your yard and price it there.