How long does a deck last

There are two decks, and they age differently

The frame — posts, beam, joists, ledger — is treated lumber under cover of the decking, out of direct sun and mostly out of standing water. The surface — decking boards, guard, stairs — takes the sun, the rain, the furniture and the feet.

The surface almost always goes first, and that is good news: re-decking a sound frame is a fraction of the cost of a new deck. It is also why "how long does a deck last" has no single answer — the two halves are on completely different clocks, and a well-built frame commonly outlives two surfaces.

The six details that kill decks

Decks rarely wear out. They rot, and rot needs trapped water. Every one of these is a place where water sits instead of leaving:

Notice that four of the six are decided at build time and cannot be maintained into existence afterwards. That is the real answer to the question: how long a deck lasts is mostly set in the week it is built.

What material actually changes

Material changes the surface's clock and barely touches the frame's, because the frame is treated lumber regardless of what you walk on.

Treated pine resists decay well and is the standard frame material. As decking it is the shortest-lived aesthetically — it checks, splinters and greys — but it is cheap to replace board by board.

Cedar and redwood are naturally durable in the heartwood, stable, and pleasant underfoot. Sapwood is not durable, and grade matters more than species name.

Composite and PVC do not rot, which removes the surface from the equation entirely. They are not maintenance-free — they stain, they can fade, and the frame under them ages exactly as before. Their failure mode is cosmetic, and a scratched composite board cannot be sanded back the way wood can.

Tropical hardwoods are extremely durable and extremely dense, which makes them slow to install and hard on tools. They also want regular oiling to keep their colour, or they silver like everything else.

The comparison in decking materials compared puts these side by side.

Extending it

At build time, which is where the leverage is: post bases instead of buried posts, sealed cut ends, flashing over the ledger, corrosion-rated hardware throughout, joist tape over the joist tops so fastener holes are not sitting in a puddle, and a frame that drains rather than one that ponds.

Every year: clear the gaps between the boards, clear the leaf litter from under the deck, check that grade and downspouts still carry water away, and look at the post bases and the ledger line. Ten minutes with a torch under the deck once a year finds things five years before they are visible from above.

On its own schedule: clean and recoat the sunny horizontal areas when the water stops beading — see the stain guide.

When to repair and when to replace

Repair when the frame is sound and the problem is on top: soft boards, a wobbly guard, popped fasteners, worn finish. Re-decking a good frame is the best-value job in the whole category.

Replace when the frame itself is going: soft posts at the base, a rotten ledger or a rotten rim joist behind it, footings that have heaved out of line, or a frame built to a standard the current code would not accept. Patching a failing frame spends real money on a deck that still has to come out.