Per square foot is the only composite decking number you can act on — multiply it by your deck area and you have a figure you can hold a quote against. The problem is that three different things get sold under that name.
| What you’re pricing | Per square foot | What’s included |
|---|---|---|
| Boards only | $5 – $14 | Decking boards |
| Boards + substructure | $7 – $19 | Boards, joists, framing, clips, fasteners |
| Fully installed | $16 – $45 | Everything above, plus labour |
This page is the board-level version of that table: how a per-square-foot figure is built from a board price, what moves it up and down, and what to check before you accept one. If you want the deck totals first, the main cost guide covers finished decks by size and against timber.
The per-square-foot price, by board type
| Board | Material cost / sq ft | Typical lifespan |
|---|---|---|
| Entry-level uncapped | $5 – $9 | 10–15 years |
| Mid-range capped | $9 – $16 | 25–30 years |
| Premium PVC / mineral core | $16 – $32 | 30–50 years |
The gap between those three rows is not marketing. It is the difference between a board with a co-extruded polymer cap bonded on all four faces and one without a cap at all — and it shows up eight or ten years later as staining, swelling or a colour that has gone grey.
How a board price becomes a per-square-foot price
This is the conversion almost no listing does for you, and it is where two quotes for the “same” board end up 30% apart.
A decking board is sold by the piece or by the lineal metre, but a deck is bought in area. The bridge between them is the board’s covered width × length:
- Coverage per board = width (m) × length (m) = m²
- Convert to square feet = m² × 10.764
- Price per square foot = board price ÷ coverage in sq ft
- Add waste = × 1.08–1.10 for offcuts and rip cuts at the edges
Here is what that does to the same two prices — a $28 board and a $52 board — across four common profiles:
| Profile (W × T) | Length | Coverage per board | At $28/board | At $52/board |
|---|---|---|---|---|
| 138 × 23 mm | 2.9 m | 0.40 m² / 4.31 sq ft | $6.50 /sq ft | $12.07 /sq ft |
| 146 × 25 mm | 3.6 m | 0.53 m² / 5.66 sq ft | $4.95 /sq ft | $9.19 /sq ft |
| 150 × 25 mm | 4.0 m | 0.60 m² / 6.46 sq ft | $4.34 /sq ft | $8.05 /sq ft |
| 165 × 25 mm | 5.8 m | 0.96 m² / 10.30 sq ft | $2.72 /sq ft | $5.05 /sq ft |
Read the bottom two columns rather than the middle one. The identical board price swings the per-square-foot cost by 2.4×, purely on length and width. That is not a trick — a 5.8 m board covers more than twice the area of a 2.9 m board of similar width, and short boards lose more to offcuts on a real deck.
It is also why per-square-foot comparisons between a big-box listing and a supplier quote so often look wrong: they are frequently quoting different profile lengths against the same deck.
What moves the per-square-foot number
Four things, in order of how much they move it.
Board type and cap. $5–$9, $9–$16 and $16–$32 per square foot are three different products, not three prices for one product.
Length and width. As above — worth up to 2× on its own.
Colour and surface finish. Variegated and multi-chrome boards, brushed or deep-embossed surfaces and non-standard colour matching all add cost, and they usually add it as a line item rather than in the headline rate.
Volume. A single board from a retailer, a pallet from a distributor and a container from a factory are three different price bases. Retail per-square-foot pricing includes the retailer’s margin and often a rebate structure; factory pricing is quoted per m² FOB and is not comparable without freight and duty added.
Price per square metre — for Australia, the UK and Canada
Most of the world quotes decking in m². Convert with × 10.764, or use these:
| What you’re pricing | Per sq ft | Per m² |
|---|---|---|
| Entry-level uncapped, boards | $5 – $9 | $54 – $97 |
| Mid-range capped, boards | $9 – $16 | $97 – $172 |
| Premium PVC / mineral core | $16 – $32 | $172 – $344 |
| Boards + substructure | $7 – $19 | $75 – $205 |
| Fully installed | $16 – $45 | $172 – $484 |
One more conversion that catches buyers out in Australia: boards are often listed per lineal metre, not per m². Divide the lineal price by the board width in metres — a 138 mm board at $18/lm is $18 ÷ 0.138 = $130/m². Do that before comparing anything.
What’s inside an “installed” per-square-foot figure
An installed rate is a bundle. Roughly:
| Line | Share of the installed total |
|---|---|
| Decking boards | 40 – 55% |
| Substructure (joists, bearers, posts) | 15 – 25% |
| Fixings, clips, fascia, stair nosing | 5 – 10% |
| Labour | 20 – 35% |
| Waste and disposal | 2 – 5% |
Two consequences follow. The first is that the boards are usually just under half of what you pay — which is why shaving $1/sq ft off a board rarely moves the total as much as people expect. The second is that a quote which only prices a boards rate has not quoted a deck; it has quoted material.
Why two quotes for the same deck differ by 30% or more
In practice, four things:
The frame spec. Treated timber, aluminium and steel framing are priced very differently, and the frame is the line most often left vague.
Fixings in or out. Hidden clips, starter clips, screws, fascia and nosing are commonly separate lines. Included or bolted on moves the effective unit rate by 8–15%.
Waste allowance. A quote built on 5% waste and one built on 15% are not in disagreement about the board price — they are disagreeing about how much of your money goes in the skip.
Stairs and railing. Railing runs $30–$70 per linear foot installed on its own; a deck with stairs can carry a third of its cost in the access rather than the floor.
The factory version: per m², FOB
If you are buying by the container rather than by the deck, per square foot stops being the useful unit. Trade quotes are written per m², FOB, with three other numbers doing the work: the minimum order quantity per profile, how many m² load into a 40HQ, and the payment terms.
To compare a factory quote with a retail per-square-foot price, convert first: an FOB price of $11/m² is $1.02/sq ft before freight, duty and port charges. That gap between a landed trade cost and a retail per-square-foot rate is the retail channel, not the product. If you are sourcing at volume, the quote you want states the profile, the m² per container and the lead time — ours runs 25–30 days before freight.
Six things to check before you accept a per-square-foot quote
- Which of the three figures is it — boards, boards + substructure, or installed?
- What board — capped or uncapped, solid or hollow, and what thickness?
- What profile and length — a per-square-foot rate without them
is not a comparable number. - Waste allowance — 5% or 15%? On a 400 sq ft deck that difference alone is 40 sq ft of board.
- Is the frame quoted — treated timber, aluminium or steel, and at what joist spacing?
- Does it include stairs, railing and fascia — the three lines most often left out and later added.
A quote that survives all six can be compared with another quote. One that doesn’t is a number, not a price.
FAQ
How much is composite decking per square foot?
$5–$14 per square foot for boards alone, $7–$19 including substructure, and $16–$45 fully installed. Board type decides which end of the range you land on: uncapped $5–$9, capped $9–$16, PVC or mineral core $16–$32.
How many square feet does a composite deck board cover?
Depends on the profile. A 138 × 23 mm board at 2.9 m covers 4.31 sq ft; a 150 × 25 mm board at 4.0 m covers 6.46 sq ft; a 165 × 25 mm board at 5.8 m covers 10.30 sq ft. Divide the board price by the coverage to get a true per-square-foot price — the same board price can differ by 2.4× depending on profile.
Is composite decking cheaper per square foot than wood?
No, not up front. Capped composite is $9–$16 per square foot against $3–$6 for pressure-treated pine. It narrows or reverses once maintenance is counted — pine needs staining or sealing every two to three years, composite needs soap and water.
How much does composite decking cost per square metre?
Multiply the per-square-foot figure by 10.764: $5–$9/sq ft is roughly $54–$97/m², $9–$16 is $97–$172, and $16–$32 is $172–$344. Installed rates of $16–$45/sq ft become $172–$484/m².
Why is a big-box per-square-foot price lower than my installer’s?
Usually three reasons: the retail figure is boards only, it is quoted on the longest profile in the range, and it excludes clips, fascia, waste and labour. Compare the board profile and what’s included before comparing the rate.
Does composite decking cost less by the container?
Yes, on a different basis. Trade pricing is quoted per m² FOB with a minimum order quantity per profile, tiered by container utilisation, and freight, duty and port charges sit outside the unit price. An $11/m² FOB price is about $1.02/sq ft before those are added.