Which decking board actually lasts in Pakenham and the Cardinia Hills
For a normal Pakenham or Officer backyard the honest answer is merbau at $280 to $380 per m² fitted, or capped composite at $380 to $580 per m² if you never want to oil again. Treated pine at $250 to $320 saves money on day one and hands it back around year 12. Up in Cockatoo, Emerald and Pakenham Upper the choice narrows: AS 3959 names the timbers permitted in bushfire areas, and blackbutt, spotted gum, red ironbark and merbau are the four you will be offered.
Decking board specification table, 2026 Cardinia rates
Fitted rates include the substructure, the boards and the fixings on a straightforward ground-level deck. Expected life assumes the maintenance in the next column actually happens.
| Board option | Typical fitted cost | Expected life here | Maintenance load | Warranty | Who it suits |
|---|---|---|---|---|---|
| H3 treated pine, 90 x 22 | $250 - $320 / m² | 12 - 15 years | Clean and oil every 12 months, or it greys and splinters | Board warranty on the treatment only; our workmanship cover applies to the frame | Rental turnarounds, a deck you expect to replace with an extension |
| Merbau (kwila), 90 x 19 | $280 - $380 / m² | 25 - 30 years | Oil every 12 to 18 months; tannin bleeds for the first season | No product warranty on natural timber; workmanship cover on the build | The default family deck in Pakenham, Officer and Cardinia Lakes |
| Spotted gum or blackbutt, 86 x 19 | $380 - $480 / m² | 30 years plus | Oil every 12 to 18 months; hard, needs pre-drilling at ends | No product warranty; graded to AS 5604 natural durability | Front verandas, anything on show, BAL-29 hills builds |
| Red ironbark, 86 x 19 | $400 - $520 / m² | 30 years plus | Very hard, very stable, oil every 18 months | No product warranty; top natural durability class | Exposed hills decks with heavy weather and ember risk |
| Uncapped composite | $380 - $470 / m² | 15 - 20 years before it looks tired | Wash twice a year; no oil | Usually 10 to 15 years, structural only | Tight budgets that still want no oiling; shaded decks |
| Capped composite | $450 - $580 / m² | 25 years plus | Wash twice a year; no oil, no sanding | 25 year fade and stain warranty, registration usually required | Busy families, pool surrounds, anyone done with annual oiling |
| Aluminium framing under any board | add $60 - $110 / m² | Outlasts the boards | None | Manufacturer structural warranty, commonly 15 to 25 years | BAL-40 hills sites, damp shaded ground, decks over reactive clay |
Indicative Cardinia Shire rates for 2026. A firm number needs a measure and a look at the ground. Call (03) 9022 6418.
What the letters and numbers on the board actually mean
Treated pine carries an H rating that tells you where the timber is allowed to sit, not how good it is. H3 is treated for outdoor use above ground, which covers deck boards, joists and bearers that never touch soil. H4 is treated for in-ground contact and is what a buried post has to be. Getting that backwards is one of the most common faults we find under old Pakenham decks: H3 posts sunk straight into clay go soft at the ground line inside 8 to 10 years and the whole frame starts to move with them. Every cut you make in treated pine also opens up untreated timber in the middle, so each cut end needs an end sealer brushed on before it goes down. It takes a minute a cut and it is the difference between a frame that lasts and one that rots from the ends inwards.
Hardwoods are not treated, they are graded. AS 5604 sorts species into natural durability classes, with class 1 the most durable, and spotted gum, blackbutt, red ironbark and merbau all sit at the durable end for above-ground use. The rating only covers heartwood. Sapwood in any species is food for lyctid borer, which is why decking hardwood should be sold to you as sapwood-free or borer-treated, and why a suspiciously cheap pack of hardwood is worth a second look.
Board size decides the framing under it. Nineteen millimetre hardwood wants joists at 450mm centres, and we hold 450mm under 22mm treated pine as well because that is what stops the bounce people complain about. Composite is where budgets get caught: most brands call for 300mm to 400mm centres, and several require 300mm for boards laid on an angle. That is roughly a third more joist timber than a merbau deck of the same size, and it needs to be in the quote before you compare the two. If a composite quote matches a timber quote line for line on framing, the framing is wrong.
Two more words worth understanding. Capped composite has a bonded polymer shell around the core, and that shell is what the 25 year fade and stain warranties are actually written against. Uncapped composite is the same material all the way through, so it chalks, fades and holds a red wine stain. The supply difference is usually $40 to $70 per m², which makes it the best value upgrade in the composite range. And 316 stainless fixings are not a sales add-on in hardwood: merbau, spotted gum and ironbark are acidic, they react with galvanised screws, and you get black tears running down every board within two summers. Stainless adds around $120 to $250 on a 30m² deck.
The local conditions that decide the spec
Two different climates in one shire. The Pakenham and Officer flats get roughly 800mm of rain a year with hot, dry, high-UV summers. Emerald, Cockatoo and Gembrook sit in the wettest pocket of the Dandenongs at well over 1,000mm, with shade, tree litter and ground that stays damp into November. A board specification that is comfortable in Cardinia Lakes can be marginal on a shaded south-facing Cockatoo deck. Up there we lift the deck clear of the ground, keep the sub-deck ventilated, and lean towards spotted gum, ironbark or capped composite rather than pine.
Reactive clay. Most of the growth corridor sits on Class M to H1 reactive clay under AS 2870, which swells and shrinks with the seasons and moves footings with it. That does not change which board you pick, but it does change what has to go under it: deeper pad footings or screw piles below the active zone, not the short stumps that look fine in October and heave in July. The build process page covers what we do at footing stage.
Bushfire overlay. If your address sits in a Bushfire Management Overlay, and most of Cockatoo, Emerald, Gembrook, Pakenham Upper and Beaconsfield Upper does, then AS 3959 sets the construction for your BAL rating. AS 3959 names seven bushfire-resisting timbers, and the four regularly sold as decking are blackbutt, spotted gum, red ironbark and merbau. From BAL-29 upwards the deck has to be built from those, from non-combustible material, or from a tested system, and the boards immediately against the house are treated more strictly than the rest of the deck because that is where embers collect. Expect 15 to 25 per cent more in material cost than the same deck in Pakenham. Our Cockatoo and Emerald pages go into the hills specifics.
Sun. A north or west-facing deck in Pakenham cops UV index 11 and above through January. Dark boards, timber or composite, run far hotter underfoot than light ones in that sun, and dark composite is the worst of them. If the deck is for kids and bare feet and it faces west with no cover, either go a lighter colour or plan a pergola over it at the same time.
The cheap specification that fails early here
There is a version of a deck that is always about 20 per cent cheaper than everyone else, and it is the same five decisions every time. Untreated or H2 pine in the frame, because it sits in the rack next to the H3 and looks identical. Joists at 600mm centres instead of 450mm, which saves a few lengths of timber and gives you a deck that flexes underfoot from the first summer. No end sealer on cut ends. Short stumps poured at 600mm into clay that moves more than that. And boards butted hard against the house with no drainage gap, which traps water against the bearer and the wall frame.
None of those five is visible when the deck is finished. All five are visible at year six. The repair is not really a repair, it is a rebuild of the substructure with the boards lifted, which is why we spend the first part of a quote under the existing deck rather than looking at colours. If your current deck already feels soft underfoot, read spongy deck boards before you spend anything.
Not sure what is under your existing deck, or which board suits your block and aspect? We will tell you on site, free, including when the answer is that you do not need us yet.
☎ Call (03) 9022 6418What "commercial grade" and similar words are worth
Nothing, on their own. There is no Australian Standard behind "commercial grade", "premium grade", "architectural" or "builder’s select" as applied to decking. They are marketing words and they vary by supplier. The words that do mean something are the ones with a standard or a number attached: H3 or H4, the species name, the durability class, 316 stainless, the board dimensions in millimetres, the joist centres in millimetres, and the actual warranty document.
So when you compare quotes, ignore the adjectives and ask for six things in writing: species and grade of the boards, board size, treatment level of every framing member, joist and bearer centres, fixing type, and the footing type and depth. Any builder who works to a specification can answer all six in a minute. On the warranty, read whether it is pro-rata, whether labour is included or only the boards, and whether it requires registration within 30 to 90 days of installation, because plenty of composite warranties are quietly void because nobody registered them. Our quote comparison guide sets out the same list in a form you can take to three quotes.
What we would specify on a typical local house
For a standard 25 to 35m² rear deck on a 2010s or newer Pakenham, Officer or Cardinia Lakes estate home, ground level, family use: merbau 90 x 19 on H3 treated pine joists at 450mm centres, H4 posts on 1.2m concrete pad footings or screw piles, 316 stainless fixings, boards pre-oiled before laying, and a drainage gap where the deck meets the house. That lands in the $280 to $380 per m² band, so $8,000 to $12,000 for a 30m² deck, and it will still be a good deck in 25 years if it gets oiled.
Change one thing and the answer changes. If nobody in the house is going to oil a deck, specify capped composite instead and accept $380 to $580 per m²: over 25 years the oiling you skip is worth roughly $350 to $700 a year in product and a weekend, so the payback usually lands somewhere around year 8 to 12. If the address is in the hills with a BAL-29 rating, specify spotted gum or ironbark and budget the extra 15 to 25 per cent. If the deck is over 1m above ground, the balustrade is not optional and the substructure needs engineering, which is a different conversation and a different price. Our timber versus composite comparison works through that trade-off with the numbers side by side.
When a cheaper answer is the right one
We turn work down most weeks. If your existing deck has a sound frame and tired boards, restoration at $25 to $55 per m² is a far better use of money than a new deck, and the restoration cost guide shows where that line sits. If you are selling within twelve months, a sand and re-oil will do more for the sale than a new deck will return. If the deck is under 20m² and under 800mm high you are inside the building permit exemption, so keep it there rather than pushing to 22m² and adding permit and surveyor cost for two extra metres. And we do not do concrete, paving or landscaping: if what you actually need is a paved alfresco rather than a deck, we will say so and you will need a different trade. Sizing it first? Use the how much decking do I need page, and if the budget is the constraint, start with the budget deck options.
Get a board specification for your block, in writing
Send your suburb and rough deck size and we come back within 1 business day with a specification and a price band, before any site visit.