Composite vs Wood Decking: What the Premium Really Buys

By the TheJobCalc editorial team · Updated September 3, 2026

Short answer: Composite decking costs roughly two and a half to three and a half times pressure treated boards, but boards are only about an eighth of a deck bill, so the finished deck costs around half again as much, more if the railing goes composite too. In exchange you drop sealing every one to two years for the life of the deck. On a horizon of fifteen years or more the upkeep usually pays for the difference.

The board price is not the deck price

Composite boards are startlingly more expensive than pressure-treated pine per square foot, and that number gets quoted as if it were the whole story. It is not. The frame under the boards is the same treated lumber either way, the footings are the same, and so is most of the labour. Only the decking line, the fasteners and, if you choose it, the railing change.

What changes on the whole deck

Take the deck cost calculator’s 16 × 12 ft example and swap only the boards from the placeholder pressure-treated price to a composite price three times higher, with hidden fasteners at roughly double the screw cost:

Line	Wood	Composite boards only	Composite boards and railing
Decking	1.0×	3.0×	3.0×
Fasteners	1.0×	2.0×	2.0×
Railing materials	1.0×	1.0×	2.5×
Everything else	same	same	same
Whole deck, approx.	1.00×	1.27×	1.51×

So the honest premium for composite is about a quarter to a half more for the finished deck, not three times. The railing decision matters as much as the boards, because railing is already a larger line than decking on an elevated deck.

What the premium buys

No sealing. Treated pine wants a cleaner and a water-repellent finish every one to two years to keep from greying, checking and splintering. That is a weekend and a few hundred square feet of product each time, for the life of the deck.
No splinters, no checking, no cupping — boards stay flat and the gaps stay even.
Colour that holds on capped products; early uncapped composites faded and stained, which is where the material’s bad reputation came from.
Longer life, typically warranted 25–50 years against rot and structural failure, against a treated deck surface that is usually tired at 15–20.

What it does not buy

A maintenance-free deck. Composite still needs washing, and the treated frame beneath it still rots if it is not flashed and drained properly.
Freedom from the frame. Most composites require joists at 16 in centres or closer (12 in for diagonal boards) and specific hidden fasteners; check the span table before pricing.
Coolness underfoot. Dark composite in full sun gets hotter than wood.
Stiffness. Composite is heavier and more flexible than wood, which is another reason for the tighter joist spacing.

The per-year comparison

Put a value on your time and the finish products, count the sealing rounds over the years you expect to own the deck, and add them to the wood price. On a fifteen-to-twenty-year horizon the sealing rounds alone usually close most of a 25–50% gap; on a five-year horizon they do not. Run the deck cost calculator twice with your two board prices and your railing choice, and compare against your own number of sealing weekends.

Deck Cost Calculator

Build an itemised estimate for a new deck — footings and posts, framing, decking with waste, fasteners, railing by the foot, stairs by the step and labour scaled for height — from prices you collect locally, so the total fits your lumber yard and your contractors rather than a national average.

Open the Deck cost →

Frequently asked questions

How much more does a composite deck cost than wood?

The boards cost roughly two and a half to three and a half times pressure treated pine, but boards are about an eighth of a deck bill. The finished deck typically comes out around a quarter to a half more, the higher figure when the railing is composite as well. The frame, footings and most labour are unchanged.

Does composite decking need maintenance?

Less, not none. It needs washing and it can scratch or fade slightly, but it never needs sealing, sanding or staining, which treated wood wants every one to two years. The treated frame under any deck still needs proper flashing and drainage.

Can I put composite boards on my existing deck frame?

Often, if the joists are sound and at 16 inch centres or closer, which most composites require. Joists at 24 inches must be added to or replaced. Check the manufacturer span table and the condition of the ledger and beams before spending on boards.

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Deck cost breakdown Board gap Joist spacing

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