How long does a timber deck last and what maintenance does it need?

A deck faces the harshest exposure of any surface on a house: direct ultraviolet light, wetting and drying cycles, foot traffic and, on the underside, ground moisture. Australian sun is the dominant factor, and it degrades both the coating and the timber surface beneath it.

The maintenance that matters

• Recoat on a schedule rather than when it looks bad. Once the timber is grey, the surface has already degraded and needs far more preparation.
• Clean before recoating, and let it dry properly. Coating over a damp deck traps moisture.
• Keep the gaps between boards clear. Debris holds moisture against the timber and against the fixings.
• Ensure water drains away underneath rather than pooling, and keep vegetation off it so air can move.
• Check the fixings and the bearers annually, because the structure fails long before the surface looks dangerous.

Where decks actually fail

Rarely in the middle of a board. The failures are at the ends where end grain absorbs water, at the fixings, at the junction with the house where the ledger is fixed to the wall, and at the posts where they meet the ground or a footing. Those are the places to inspect, and the ledger connection in particular is a safety matter rather than a maintenance one.