It's the first thing nearly everyone asks, and fair enough. You want a number before you let a tradie loose out the back.
Trouble is, "a deck" can mean a low platform off the back door, or a raised entertaining area hanging off posts over a sloping block with a balustrade and stairs. Those two jobs aren't in the same postcode price-wise.
So rather than pretend there's one figure, here's what actually moves the cost around the Gong. Once you've got your head around the levers, the ballpark makes a lot more sense — and you'll see why a real quote is the only number worth much.
What you're roughly looking at per square metre
Rough guide for the Illawarra: a simple low-set treated pine deck tends to land somewhere around $350 to $500 per square metre supplied and built. Go to a hardwood like merbau or spotted gum and you're more like $500 to $750 per m². Composite (Trex, Modwood and the like) usually pushes past $700 and can sit closer to $900 per m² once the board cost's in there.
These are honest middle-of-the-road numbers. Not the cheapest quote you'll ever be handed, and not a horror story either — they assume a fairly straightforward job. The minute the block slopes, access gets tight, or the deck sits up high, that per-metre rate climbs. Sometimes a fair bit. A 20m² deck on flat lawn is a completely different animal to a 20m² deck three metres off the ground on a Mount Keira slope.
Size catches people out too. Bigger isn't automatically dearer per metre — there's a fixed chunk of setup, design and footings in every job no matter what, so a little 8m² deck can feel pricey by the square metre. Spread that same setup over 30m² and the rate comes down.
The things that really drive the price
Material's the obvious one, and it's a proper fork in the road. Treated pine is the budget option and there's nothing wrong with it — it just wants oiling and a bit of love, and out here the salt air and the southerlies chew through everything, so pine ages quicker near the coast. Merbau and spotted gum look the part and go the distance; spotted gum especially is a local favourite, and deservedly so. Composite stings more up front, then you're basically done with maintenance — which plenty of folks near the water reckon is money well spent.
Then there's height off the ground. This is the sneaky one.
A deck sitting just above the lawn is mostly getting your bearers and joists level and laying boards. Lift it up and you've suddenly got deeper footings, taller posts, a beefier subframe, stairs. Push past one metre off the ground at any point and you're legally into balustrade territory — and that handrail isn't a few extra boards, it's design, materials and labour piled on top.
A few other things that nudge the number:
- Slope and footings — flat block, easy day. Cut into the escarpment side of a hill and you're up for stepped footings, retaining to think about, and a lot more digging.
- Site access — can the ute and a barrow get round the side, or are we walking every length of timber through the lounge room? Tight access on a narrow block adds hours, and hours are dollars.
- Demo of the old deck — pulling up a rotten one, carting the waste off and seeing what's lurking underneath all eats time before a single new board goes down.
- Council and approvals — depending on height, size and where you sit (Wollongong, Shellharbour, Kiama and Shoalhaven all have their own quirks), you might need approval. Worth sorting early so it doesn't stall the job halfway.
Those post-war fibro and brick places dotted all over the Illawarra often hide quirky levels and tired old footings. The newer estates down Shellharbour and Nowra way come with their own access headaches instead. Both can be done well. They just need eyes on them in person.
Why a quote beats any number on the internet
You can run every "deck cost calculator" out there and still be twenty per cent off, because none of them have stood in your backyard. The slope, the soil, how high you want to sit, whether there's an old deck to tear out, where the boards have to be carried from — that's the stuff that sets the real figure. You can't see any of it from a webpage.
Here's what trips people up: two decks the same size on the same street can quote thousands apart, just because one's flat with side access and the other's up on posts over a drop with a balustrade round it. Neither chippy is having you on. The blocks are simply different.
Good news is a proper quote costs you nothing and doesn't take long. Dave'll come out, have a look at the block, run through timber options against your budget and how you actually want to use the space, then give you a real number instead of a guess. No obligation, no sales spiel.
If you're weighing up a new deck anywhere from Helensburgh down to Nowra, give us a bell on 0414 007 351 or grab a free quote. Happy to talk it through and tell you straight what we reckon it'll take. We're local, licensed and insured, and you'll be dealing with Dave the whole way.
Want a hand with this at your place? Get a free quote or call 0414 007 351.