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Pine, Kwila or Vitex? Choosing the timber for a deck
The boards are the part of a deck everyone sees, and the easiest part to choose. We build in treated pine, Kwila and Vitex, and on the four decks below the timber was decided by what was already there, how the deck would be used and what the owners wanted it to look like in ten years. What sits underneath barely changed.
Four decks, three timbers
Torbay: treated pine, chosen to match the decks already around the house.
One Tree Hill: smooth Kwila, cut in a half-moon around a round stainless plunge pool.
Mission Bay: smooth Kwila again, finished before the pool arrived.
Meadowbank: smooth Vitex, curved around an existing concrete pool.
Torbay: pine, because the house already had it
Two doors opened onto old timber steps and a patch of uneven pavers that nobody used. The new deck sits flush with the house, runs out to both sides and steps down at the end to the rest of the yard. It's about 30 m², 700 mm off the ground.
The boards are 140 × 32 grip-tread premium pine. The owners already had pine decks around the house and wanted the new one to match, within a budget. Hardwood would have given a more premium look, a longer life and less movement and cracking over time, but it would have looked out of place next to everything else. That was their call, and the right one for this house.
The grip-tread is laid grooves down. It can go either way: grooves up for slip resistance, grooves down to help water run off under the boards. Down is our preferred way, and it matched the existing decks.
2 weeks on site
One Tree Hill and Mission Bay: Kwila around a round pool
Both of these are half-moon decks around round Outback stainless pools, and both are 140 mm smooth Kwila. Kwila is a dense hardwood with a deep red-brown colour that suits a pool edge, where the boards are cut short, scribed to a curve and looked at closely.
At One Tree Hill the boards are 140 × 19 on 140 × 45 joists and laminated 190 bearers built from two 45s, all H3.2, on 125 × 125 H5 house piles. PlaceMakers supplied all the timber. Each board around the pool was scribed to the shell and cut individually with a jigsaw.
At Mission Bay the deck is 6 m by 4 m with a 5 m by 1 m return along the house, so every door now opens onto one surface that leads to the pool. It sits on 140 × 45 H3.2 SG8 joists and 190 × 45 H3.2 SG8 bearers, on 125 × 125 H5 concrete piles, fixed with 65 mm stainless Torx-head screws.
5 to 6 weeks at One Tree Hill, 3 weeks at Mission Bay
Meadowbank: Vitex for a deck of many shapes
Meadowbank is a deck that's several shapes rather than one: it wraps an existing concrete pool with curved coping, meets new porcelain paving, and carries two flights of stairs about 1.2 m each, all with wrapped details. It's 140 × 19 smooth Vitex on 190 joists over double 190 bearers, with a cantilevered edge and a double boundary joist throughout.
Some of the curved boards carry up to three different angles, and the frame was built with extra bearers so every cut board is supported.
About 10 weeks on site
What actually decides it
What's already there. A new deck next to an existing one reads as a patch if the timber doesn't match. Torbay went pine for exactly that reason.
How it's used and seen. A pool edge, a curve or a step is looked at up close, and hardwood holds a clean cut and a tight line. A broad deck that mainly needs to be flat and dry is where pine earns its place.
How long, and how much movement. Hardwoods generally last longer and move and crack less over time than pine. Pine costs less, and on the right job it's the sensible choice, not a compromise.
The part that doesn't change. On all four decks the piles are 125 × 125 H5 in concrete, the framing is H3.2, and the fixings are stainless. The frame costs the same under pine as under Kwila, and it decides whether the deck is still flat years from now. More on that in what holds a deck up.
Where we fit
We build decks in all three timbers, from a small pine deck to a curved hardwood surround, and we build the frame under every one the same way. At the site visit we'll talk through the timber against the house, the use and the budget.