The gap a carpenter's fee actually costs you
Our decking calculator's own worked example already prices this job both ways: about $620 in materials alone against $2,400 to $3,360 fully installed by a carpenter, a gap of roughly $1,780 to $2,740 that's entirely labour. Unlike a concrete pour, decking doesn't hand you a race against a curing clock, but there is one job most people skip doing by hand: boring the stump holes for the posts underneath. A one-person post-hole borer covers that for about $100 to $120 a day dry hire, a small dent in a saving worth fifteen to twenty times as much, as our decking calculator's own docket already prices in.
What it actually costs
Same worked example as our decking calculator: a 4 m × 3 m deck in treated pine, 12 m² once boards, joists and the standard 10% wastage allowance are counted.
| Option | What it includes | Cost |
|---|---|---|
| DIY, materials only | 141 linear metres of treated pine board, joists and fixings for the same 12 m² deck, you supply the labour | $620 |
| DIY, plus borer hire | Same materials, plus a one-person post-hole borer to dig the stump holes (about $100–$120/day dry hire) | $720–$740 |
| Hire a carpenter (supply & build) | Materials, footings, framing, boards and fixing all done for you | $2,400–$3,360 |
Carpenter figures are supply-and-build quotes for a standard timber deck, not labour-only; DIY figures assume you already own basic hand tools and only need to hire a post-hole borer for the footings. A council permit application, where one's required, is a separate cost again, not included in either total.
Why the permit is the step worth checking first, not last
Paving and concrete's real DIY risk shows up months or years later, once an under-compacted base finally settles. A deck's real risk can show up on day one, because unlike laying pavers, putting one up is often a regulated building activity in its own right, not just a landscaping job, and the rules genuinely don't match from state to state. NSW's own planning department exempts a deck from council approval entirely if it's no bigger than 25 m², sits no more than 1 metre above the ground at floor level, and reaches no more than 3 metres at its highest point. Victoria draws the line differently again: a building permit applies to deck construction "regardless of the deck's height or size", with a separate planning permit layered on top once a deck rises above 1 metre or covers more than 20 m². A carpenter who builds decks for a living already knows which of those rules applies in your council area. A DIYer starting from a hardware-store guide has to go and find out themselves, and the two states above don't even agree with each other on the answer.
Footings are the other place a licensed builder's experience shows. The posts under a deck typically need to sit 450 to 600 mm into stable ground, with the timber frame itself kept at least 450 mm above soil level so it can ventilate rather than sit against damp earth. Get the depth wrong and the fault doesn't show up while you're building, it shows up later as a deck that rocks, settles unevenly, or fails an inspection the day you try to sell the house. Skipping a required permit carries its own separate cost on top of any rework: Victoria's own penalties for unauthorised building work run up to $18,000 for an individual, well past what a carpenter's fee was ever going to add to the job.
Common questions
Is it cheaper to build your own deck or hire a carpenter?
Yes, on labour alone. Building your own 4 m × 3 m treated pine deck costs about $620 to $740 in materials, including a post-hole borer hire, against $2,400 to $3,360 to hire a carpenter to supply and build the identical deck, a saving of roughly $1,780 to $2,740. That gap excludes any permit application and assumes the footings are done to code, which is what the carpenter's price is largely paying for.
Do you need a permit to build a deck in Australia?
It depends heavily on your state and the deck's size, and the rules genuinely don't line up between states. In NSW, a deck can be exempt from council approval if it's no more than 25 m², sits no more than 1 metre above ground at floor height, and reaches no more than 3 metres at its highest point. Victoria applies a building permit to deck construction regardless of size, with an added planning permit once a deck exceeds 1 metre in height or 20 m² in area. Always confirm the current rule with your own council before you start.
How deep do deck footings need to be?
Typically 450 to 600 mm into stable ground, with the timber frame itself kept at least 450 mm above soil level for ventilation. A carpenter sizes this to your actual soil and council requirements; guessing the depth is one of the more common ways a DIY deck ends up needing rework.
Does the decking material change whether it's worth DIYing?
It changes the saving's size, not the decision itself: labour is the bigger cost either way. See our companion guide on timber vs composite decking costs for how much material choice adds to the ten-year total, on top of whoever builds it.
Sources
NSW exempt-development area and height thresholds for a deck (25 m² max area, 1 m max floor height, 3 m max overall height): NSW Department of Planning and Environment, Balconies, decks, patios, pergolas, terraces and verandahs: rules for exempt development. Victorian deck building/planning permit thresholds and unauthorised-work penalties (up to $18,000 for an individual): SQM Architects, Decking Regulations in Victoria, which also gives the 450–600 mm footing depth and 450 mm timber-clearance figures. General council permit thresholds and non-compliance risk: BUILD, Do I need a council permit for a deck or pergola? Materials and installed cost bands: same Bunnings/live-fetched sourcing as our decking calculator. All fetched July 2026.