Straight answers to the questions we hear most about hardwood decking, durability classes and buying timber in Sydney and on the Central Coast. Every answer links to the detail behind it.
What is Class 1 hardwood?
Class 1 is the highest natural durability rating for timber under AS 5604, describing the decay resistance of a species' untreated heartwood. For above-ground use such as decking, Class 1 carries an indicative service range of more than 40 years. It is an indicative classification, not a warranty, and it says nothing about strength, hardness or maintenance needs.
In the Sydney Timber Supply range, Ironbark, Spotted Gum, Blackbutt, Redgum and Gympie Messmate all carry supplier-documented Class 1 above-ground durability. The full system, including what the classes do and do not tell you, is explained in our hardwood durability classes guide.
What is Class 2 hardwood?
Class 2 is the second-highest natural durability rating under AS 5604, with an indicative above-ground service range of 15 to 40 years for untreated heartwood. It is a genuine outdoor-grade classification suited to decking, fencing and general external work. As with all durability classes, the range is indicative, not a guarantee, and actual performance depends on installation, exposure and maintenance.
Jambu, Jambu Mixed, Merbau and Peninsula Blonde in our range are supplier-documented Class 2 timbers. See how the two classes compare in practice in our Class 1 vs Class 2 guide.
Is Class 2 hardwood suitable for decking?
Yes. Class 2 hardwood is suitable for decking, with an indicative above-ground service range of 15 to 40 years under AS 5604 when correctly installed and maintained. Merbau, a supplier-listed Class 2 hardwood, is the most widely stocked decking timber in the Sydney retail market.
Good detailing does the heavy lifting: ventilation gaps, ground clearance, sealed cut ends and a maintained oil finish. Browse Merbau decking or compare every species in our hardwood comparison table.
Is Class 1 hardwood stronger than Class 2?
Not necessarily. Durability class measures decay resistance only; structural strength is described separately by strength groups, and hardness by the Janka test. A Class 1 species can be weaker or softer than a Class 2 species, so the properties must be checked individually for the job.
Within our own range, supplier-documented values show the spread: Grey Ironbark is SD1 seasoned with Janka 16, while Class 1 rated Blackbutt is Janka 8.9. Our durability guide explains how durability, strength and hardness differ.
What is Queensland Class 1 hardwood?
QLD Class 1 Hardwood is the display wording Sydney Timber Supply uses for Ironbark and Spotted Gum, which are supplied as Queensland-sourced hardwoods with supplier-documented Class 1 above-ground natural durability. The underlying rating is the standard AS 5604 above-ground Class 1 classification, with an indicative service range of more than 40 years.
Both species are sold per linear metre in profiles from 86 x 19 to 135 x 35 mm. See Ironbark decking and Spotted Gum decking.
What hardwood decking is available in Sydney?
Sydney Timber Supply supplies Sydney customers with Australian hardwood decking in Ironbark, Spotted Gum, Blackbutt, Redgum and Gympie Messmate, plus imported Merbau, Jambu, Jambu Mixed and Peninsula Blonde. Profiles run from 86 x 19 mm narrow boards to 135 x 35 mm thick boards depending on species, priced per linear metre on each product page and delivered from West Gosford with delivery quoted per order.
The full picture, including how ordering and delivery work, is on our hardwood decking Sydney page.
What is the difference between Ironbark and Spotted Gum?
Both are supplier-documented Class 1 above-ground Australian hardwoods, so durability does not separate them. Ironbark is the denser and harder of the two, with supplier-documented Janka 16 for Grey Ironbark and deep chocolate-to-red colouring, but it is usually supplied to order with longer lead times. Spotted Gum shows pale gold to warm brown tones with distinctive gum-vein flecking and is one of the most widely available Australian-grown decking hardwoods.
The full comparison, including strength groups and profile availability, is in our Ironbark vs Spotted Gum guide.
Where can I buy hardwood decking on the Central Coast?
Sydney Timber Supply is a Central Coast timber supplier based at 12 Dyer Crescent, West Gosford NSW. We supply Australian hardwood decking, Merbau and structural pine across the region, with local pickup available and delivery quoted per order. Linear metre prices are shown on every product page.
Details of the local range and trade accounts are on our Central Coast supplier page, or call 0440 137 068.
How do I calculate linear metres for decking?
Divide your deck area in square metres by the board's cover width in metres, where cover width is the board width plus the gap between boards, then add a wastage allowance. For example, 20 m2 at a 90 mm cover width is about 222 linear metres, or about 245 lm with 10 percent wastage added.
Our timber calculator does this conversion for you and shows the working, and the calculator guide walks through each step by hand.
Does Sydney Timber Supply deliver timber?
Yes. Delivery is available and is quoted per order from our West Gosford base, based on load size, board length and site access. Pickup from 12 Dyer Crescent, West Gosford is also available if you prefer to collect.
See delivery and pickup for how quoting works, or include your postcode and quantities in a quote request for delivered pricing.
Reviewed by the Sydney Timber Supply team. Last updated 25 August 2026.