Composite Deck Cost & Material Calculator

26 boards and 372 clips — $1,830 of board and $276 of fastener, $2,106 together. Survey estimates rather than quotes.

The board count is not area divided by board width. It comes from the same stock-length optimiser the deck lumber calculator uses, which works out which lengths to buy and how much of each one ends up in the offcut pile. Composite comes in its own lengths, so that arithmetic is worth doing rather than estimating.

What is not in that figure is the deck. Composite is a surface. Underneath it sit joists, beams, posts and footings, all pressure-treated timber, all ageing at wood speed — and none of them priced here. A composite deck is a wood deck with a different top on it, which is the single most useful thing to know before reading any comparison including this one.

372 clips at $276, against 744 face screws at $96 for the same deck. Survey estimates both.

A face screw goes in twice at every crossing; a clip goes in once, seated in a groove milled down the board edge. So the count roughly halves and the cost roughly triples. What you get for it is a surface with nothing visible in it and a side gap set by the clip rather than by your eye.

The deck screw calculator covers that trade properly — what clips cost in time as well as money, and why a board in the middle of a run is harder to lift afterwards. It is worth reading before you commit, and this page will not repeat it.

Composite's whole pitch is that you never finish it. That is true, and it is worth something — the question is how much, and the answer needs both halves: what composite costs extra to buy, and what wood costs to keep.

This site already holds both. The purchase side comes from the same board and fastener engines every other page runs. The upkeep side comes from the deck staining cost calculator over the same deck — and the deck stain calculator owns why composite needs none of it.

Nobody selling composite publishes this comparison, and the reason is arithmetic rather than malice. Publishing what the upkeep saving is worth means publishing the purchase gap beside it, and the purchase gap is the number that loses. It is easier to say "never needs staining" and let the reader assume the saving is larger than it is.

Over 25 years, on the default deck: composite $3,183, pressure-treated pine $8,012, redwood $8,034, cedar $9,152, ipe $13,788. All survey estimates, and every one of them rests on assumptions the next two sections take apart.

Over 25 years this composite deck costs $3,183 and the same deck in pressure-treated pine costs $8,012. That is a $4,828 gap and it looks decisive.

It is not the gap. It is the gap if you pay somebody to refinish the pine.

Do the refinishing yourself and the pine deck costs $4,625 over the same window. The gap falls to $1,442 — under a third of what it was — and the composite premium takes most of those 25 years to earn back rather than most of the first decade.

Nothing else in the comparison moves like that. Not the board price, not the clips, not the species. One checkbox, a factor of three and a half.

Which is why it is a control on this page rather than a default somebody picked for you. Whether you hold the brush is a fact about your life, not about decking, and it is the fact that decides the answer.

The window is a control too, and it is the second-largest lever. Everything above is 25 years because that is where the default sits, but you can move it between 10 and 30. At 10 years the gap against pine is $802 rather than $4,828, because upkeep needs time to accumulate and the purchase premium is paid on day one. If you expect to sell inside a decade, that is your number and not the headline one.

Both figures are our own survey estimates, and so is the interval between refinishes — it moves with sun, with traffic, and with how well the last coat went on.

None of the figures above prices replacing a deck that wears out inside the window. Each one buys a deck, keeps it, and stops.

That assumption holds for some rows and not others, and the table shows service life on every one so you can see which. At 25 years, composite (25–30 years) and ipe (40–75 years) are still standing. Pressure-treated pine (15–25 years) and redwood (20–30 years) reach into the low end of theirs. Cedar (15–20 years) does not make it at all — so the cedar total is short by most of a second deck, and it is the row to trust least.

We could put a replacement in and we have chosen not to, because doing it means picking the year the money gets spent. Service life here is a survey range up to a decade wide; turning that into a date and charging for it would be manufacturing precision, which is worse than the gap it fills. Naming where the assumption breaks is honest. Filling it with an invented year is not.

Read it the other way as well, because it does not favour composite. At 25 years a composite deck is at or near the end of the life we hold for it, while an ipe deck has decades left and a redwood deck is still going. The totals say what each deck costs over the window. They do not say how much deck you have at the end of it, and that is part of what you are buying.

The calculator has a joist spacing control, and it will price whatever you put in it. It does not check whether your boards can span that far, and it is not going to pretend otherwise.

Composite board spans are product-specific. They are set by the manufacturer, they are a warranty condition rather than a suggestion, and they differ between product lines from the same company. Some composite wants closer joists than the pressure-treated board it replaces, and finding that out after the frame is built is an expensive way to learn it.

The answer is on the installation instructions for the boards you are buying, and it is worth having before you order the frame rather than after. Same as the ledger and the permit: we will tell you the question matters and where the answer lives, and we will not invent a figure to fill the gap.

It means no finishing. No stripping, no sanding, no coat every few years, none of the 8 refinishes a pine deck takes over 25 years. That is real and it is the reason composite exists.

It does not mean nothing happens to it. Composite scratches, and the scratch does not weather out the way a scratch in wood does. It fades, most in the first year. It gets hot in direct sun — hotter than timber. It still wants washing. And it sits on a wood frame that is ageing on exactly the schedule it always did.

None of that is an argument against composite. It is the difference between "no maintenance" and "no refinishing", and only the second one is what you are buying.

This calculator works from generic composite profile dimensions, not from any one product line, and it names nobody.

That is not squeamishness. We hold no brand-specific data — not board widths, not clip rates, not which profiles are sold grooved, not what any of it costs at your yard — and the only way to publish a brand comparison would be to invent the numbers in it. Every other page here refuses that, and this one is not the exception just because the query is popular.

What the query is actually asking is answerable without a name: how many boards, how many clips, what it costs, and how it compares with wood over time. That is this whole page.

Then check your own boards. Widths, thicknesses, clip rates and span limits all vary between manufacturers, and clip coverage is a warranty condition — so the figure on the box you are buying beats any figure here, including ours.

• Which brand to buy, or whether one is better than another. The section above says why.
• How far your composite can span. Manufacturer's figure, warranty condition, on the installation sheet.
• What size the framing should be. Composite sits on a wood frame and this page prices neither its size nor its adequacy.
• Anything about the ledger. The board bolting the deck to the house is the connection that fails all at once. AWC DCA 6 and your building department.
• How long a specific product lasts. The service lives here are our own survey ranges for the material, not a warranty for a product.

The deck underneath all of it — 192 sq ft, 26 board rows, 13 joists and 3 posts on a 16 × 12 ft (4.9 × 3.7 m) deck — comes from the same function the deck calculator, the deck lumber calculator, the deck screw calculator and the deck cost calculator use. Five pages, one deck, and the build fails if they ever disagree.