Trade 6 of 33Updated May 2026

A research dossier · 41 NSW + 32 QLD + 31 VIC homeowner posts · AS 1684 + BCA Volume 2 referenced

Hiring a Decking Builder
is half framing,
half plumbing.

The boards are what you see. The frame underneath + the junction with your house are what decide whether the deck is solid in 15 years and whether water gets into your wall cavity. The cheap decker undersizes joists, skips flashing where the deck meets the house, and ignores drainage falls. Five years later the boards cup, the joists rot, and the wall cavity grows mould.

450mm

Standard joist spacing for residential decking.

Height above ground = mandatory balustrade under BCA.

15 yrs

Lifespan of a properly built hardwood deck. 3 yrs if not.

How this page was built

A research dossier, not a referral page.

Sources

Reddit + Whirlpool, ProductReview, AS 1684 (Residential Timber-framed Construction), BCA Volume 2, manufacturer (Trex / Modwood / EkoDeck / NewTechWood) install specs.

Verification

Pricing cross-checked across NSW, QLD, VIC. Joist span tables verified against AS 1684. Balustrade height rules per BCA.

Funding

No decking builder pays for placement. No referral fees. Funded by the supply-side flyer service at flyers.needatrade.com.au.

Before we start

The boards are decoration.
The frame + the flashing are the job.

A deck is two trades stacked: structural carpentry below + finish carpentry above. The structural piece (footings, posts, bearers, joists, ledger + flashing) decides whether the deck lasts. The finish piece (boards, balustrade, screws) decides what it looks like at handover. The cheap quote saves on the bit you can\'t see.

The 10 questions below force the frame, the flashing, and the falls into the open. A working decking builder welcomes them — those are the lines they take pride in. A cowboy stalls — the cheap quote depends on you not asking.

Water + timber. The whole job is about controlling where the first one goes around the second one.

How much should it really cost?

Decking is priced per m² + the structural under-frame. Boards are the smaller line — joists + posts + balustrade + flashing carry the real cost.

Six lines a real decking quote shows

1Footings. Concrete footing pads. Depth + size + reo. Soil-class dependent.
2Structural frame. Posts + bearers + joists. Sized to AS 1684. Material + treatment grade.
3Ledger + flashing. Where it attaches to the house. Metal flashing pushed behind cladding. Critical.
4Boards. Species (hardwood / treated pine / composite brand). Fixings (top-screwed / hidden clip / face-screwed). Falls cut into joists.
5Balustrade. If over 1m above ground = BCA-mandatory. Glass / wire / timber / aluminium.
6Finish. Oil / stain (timber) or no finish (composite). First coat before handover.

Indicative ranges · per m²

AU 2026

Treated pine (low-set · standard)	$280 – $420/m²
Merbau / Spotted gum hardwood	$380 – $600/m²
Composite (Trex / Modwood / EkoDeck)	$420 – $700/m²
Balustrade (stainless wire balustrade · per m)	$280 – $480/m
Balustrade (glass · per m)	$450 – $780/m
Cheap quote (undersized frame · no flashing)	under $220/m²

Indicative. Elevated decks (over 1.5m), engineering certificate jobs, heritage match, BAL-zoned material substitution = upper end.

Ask this, exactly

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"Can you send the quote with footing spec, joist + bearer sizes (AS 1684), ledger flashing detail, board species + fixings, and balustrade compliance — line by line?"

How to tell a real one from a cowboy.

The decking villain looks identical at handover. The frame is hidden. The flashing is invisible. The damage shows in year five when the deck cups + the wall cavity grows mould.

Red flags — in order of how often you'll meet them

!
No ledger flashing in the quote
The metal flashing behind the ledger board (where the deck attaches to the house) is the single most-skipped element. Without it: water tracks into the wall cavity. Wall plate rot in 3–5 years.
!
Joist spacing > 450mm
Standard residential = 450mm centres. Some board manufacturers spec tighter (composite often 350mm). Wider = bouncy deck + premature board failure.
!
No falls cut into the joists
Boards need to shed water. 1:80 fall away from the house cut into the top of the joists. Cowboys lay flat → water pools → rot.
!
No balustrade where BCA requires it
Over 1m above ground = balustrade mandatory. 865mm minimum height. 125mm max gap. Cowboys build to "how it looks" not the code.
!
Wrong fixings (galv on hardwood)
Hardwood boards need stainless screws (304 minimum, 316 coastal). Galv screws stain hardwood permanently. Composite boards need their hidden-clip system — top-screwing voids the warranty.

The verification routine — 10 minutes, free

✓
State licence above threshold. Often a builder\'s licence (decks are structural).
✓
ABN on abr.business.gov.au. Public liability + workers comp.
✓
Manufacturer authorised installer for composite brands. Worth real money — keeps the manufacturer warranty alive.
✓
Two reference jobs at year 5+. Drive past one. Deck still flat + flashing still hidden behind cladding = built right.
✓
Council approval if elevated. Decks over 1m / over 10m² floor area often need CDC or DA depending on council.

Ask this, exactly

"Can you confirm the ledger flashing detail in writing, the joist spacing + fall cut, the balustrade compliance, and the fixings (stainless or hidden clip)?"

When does decking need council approval?

NSWNew South Wales

NSW Fair Trading

Builder\'s licence above $5k for residential decks.
Exempt development possible if under 1m height + under 10m² + 1m from boundary.
HBC required above $20k.

QLDQueensland

QBCC

QBCC licence above $3,300.
Building approval (private certifier) typically required.
Same threshold triggers Home Warranty Scheme.

VICVictoria

VBA

Building permit usually required above 800mm height + over 10m².
VBA-registered builder above $10k.
DBI required above $16k.

Half-time

Frame + flashing + falls. Skip any one, the deck doesn't last.

Quote anatomy, the cowboy test, council approval. The first three sort the working decking builders from the cheap operators who skip the bits you can\'t see. The next seven are how working builders tell themselves apart — and how the deck still feels solid in 2046.

When can they fit you in?

Decking builders 6–12 weeks out for standalone jobs. Spring + early summer = peak. Council approval (when needed) adds 4–8 weeks upfront. Composite material lead times occasionally stretch in peak season.

Approval window.

4–8 weeks if council approval needed. Add to install lead time.

Build duration.

20–30m² deck: 5–8 days. Larger / elevated: 2–3 weeks. Composite is faster than hardwood at install.

Weather + season.

Concrete footings need cure window. Wet conditions delay timber install. Composite less sensitive.

Ask this, exactly

"What\'s your real start window after approvals + the cure regime for the footings?"

What happens next, step by step.

1Step
Site visit + design
Levels, soil, attachment to house. Engineering input if elevated.
2Step
Approval (if needed)
CDC / DA / building permit lodged. 4–8 weeks. Composite manufacturer specs verified.
3Step
Footings
Concrete footing pads dug + poured. 7-day cure before frame work.
4Step
Structural frame
Posts erected. Bearers + joists installed. Ledger fixed to house with flashing behind. Falls cut.
5Step
Boards + balustrade
Boards laid with correct fixings + spacing. Balustrade installed where required. Stair installed if needed.
6Step
Sign-off + finish coat
First oil / stain coat (hardwood). Photos. Defects walk-through. Maintenance schedule handed over.

Hardwood, treated pine, or composite?

Option A · most popular

Hardwood

Merbau, spotted gum, blackbutt. Beautiful grain. Needs oil every 1–2 years. 15+ year lifespan when maintained.

Right when: premium natural look + you\'ll maintain it.

Wrong when: low maintenance is critical.

$380 – $600/m²

Option B

Treated pine

H3 / H4 treatment. Affordable. Cup + shrink more than hardwood. 10–15 years with regular staining.

Right when: budget-led, low-traffic, will paint or stain.

Wrong when: heavy use, high foot traffic, want natural timber look.

$280 – $420/m²

Option C

Composite (Trex etc)

Wood-plastic composite. Zero maintenance. 25-year manufacturer warranty typical. UV fade in first year then stable.

Right when: no maintenance, pool surround, rental property.

Wrong when: heritage area requires real timber, very hot climates (composite gets hot in summer sun).

$420 – $700/m²

Warranty — workmanship vs board.

Layer 01
Statutory structural
6 years (NSW · VIC) / 6.5 years (QLD) on structural framing + ledger + footings.
Layer 02
Builder's workmanship
Typically 12 months to 5 years on the build itself.
Layer 03
Board manufacturer
Composite: 25 years typical (Trex / Modwood / EkoDeck). Hardwood: nature-warranted (no manufacturer cover).
Layer 04
Insurance-backed
HBC / HW / DBI above state thresholds.

Ask this, exactly

"Could you list workmanship + composite manufacturer warranties (if applicable) + the maintenance regime needed to keep them alive?"

Height, attachment, neighbour.

Over 1m above ground
BCA-mandatory balustrade. Council approval often required. Engineering input for elevated decks.
House attachment
Ledger fixed through cladding into structural framing. Flashing pushed behind cladding. Termite-shield required in QLD.
Boundary setback
Most councils require deck 1m from boundary. Some heritage areas tighter.
Strata + apartment
Owners corporation approval. Common-property deck = building manager involvement.

Ask this, exactly

"Do we need council approval given the height + area + setback, and what\'s the balustrade requirement?"

Edge cases — get a second opinion for…

Bushfire zone (BAL-rated)
BAL-12.5+ restricts deck materials. Hardwood species + spacing rules. Some composites approved, others not.
Termite-prone areas
Termite shield mandatory at ledger + post bases (QLD especially). Steel posts often preferred over timber.
Pool surround
Within 1.2m of pool fence: anything climbable (lattice, planter, BBQ) is non-compliant. Specialist pool-deck builder may be needed.
Heritage area
Material match. Often timber-only. Decking visible from street may need council heritage approval.
Strata / multi-unit
Common-property issues. OC approval. Balcony decks have specific membrane requirements over occupied space below.
Elevated decks (over 1.5m)
Engineering certificate typically required. Posts + footings sized for wind + live load. Building permit usually needed.
Roof / balcony retrofit
Existing waterproofing membrane must not be compromised. Specialist installer required.
Sloped / stepped ground
Multi-level deck design. Stepped footings. Engineered design.
Composite material substitution
Some installers swap brands mid-job. Manufacturer warranty void if not installed per brand spec. Confirm brand on the day.

After they leave.

Decking aftercare splits by material. Hardwood: oil every 1–2 years. Treated pine: stain every 2–3 years. Composite: rinse occasionally + that\'s it. The structural frame underneath needs no maintenance — if it was built right.

Hardwood oil schedule.

First coat at handover. Re-coat 12 months later. Then every 18–24 months. Skip = grey weathered look + cracking.

Composite registration.

Trex / Modwood / EkoDeck warranties need to be registered with the manufacturer within 30 days. Cheap installer often forgets.

Defects period.

3-month walk-through after first wet season. Cup or warping shows here. Touch-ups + adjustments.

Annual rinse.

All materials: gentle hose-down + occasional deck cleaner. Pressure-washing voids most warranties.

Ask this, exactly

"What\'s the maintenance schedule for the material I chose, will you register the composite warranty for me, and what\'s your defects-period walkthrough?"

If you've read this far

A decking builder who shows you the flashing detail before the boards is not a unicorn. It's the bar.

We can introduce you to deck builders in your area who already work this way. No paid placement.

✓ No referral fees✓ Verified means all 10✓ No spam

Find a vetted deck builder Hardwood · composite · pool surround

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Trade 6 of 33.

Hiring a Decking Builderis half framing, half plumbing.

A research dossier, not a referral page.

The boards are decoration.The frame + the flashing are the job.

Hardwood

Treated pine

Composite (Trex etc)

A decking builder who shows you the flashing detail before the boards is not a unicorn. It's the bar.

Hiring a Decking Builder
is half framing,
half plumbing.

The boards are decoration.
The frame + the flashing are the job.