Iron Bark Decking

Grey ironbark decking in 86 × 19 mm and 135 × 19 mm: one of the hardest Australian hardwoods, with Janka hardness 16 kN, Class 1 durability both above ground and in-ground, and rated for bushfire decking up to BAL-19.

• Sizes: 86 × 19 mm and 135 × 19 mm
• Timber: grey ironbark (Eucalyptus paniculata and E. drepanophylla), grown in NSW and Queensland; reddish-brown to dark brown; about 1105–1120 kg/m³, the densest timber in our decking range
• Durability: Class 1 above ground, which the Queensland Government rates at more than 40 years’ expected life; Class 1 in-ground too; the heartwood is termite resistant and the sapwood isn’t susceptible to lyctid borer
• Bushfire: qualifies under AS 3959’s high-density rule for BAL-12.5 and BAL-19, but it is not on the bushfire-resisting timber list, so it can’t be used for decking at BAL-29. For BAL-29, choose Spotted Gum, Blackbutt or Merbau
• Joist spacing: 450 mm centres, as WoodSolutions recommends for decking; its deck design guide allows up to 500 mm for 19 mm hardwood, or 350 mm if the boards run at 45°
• Gaps: 3–4 mm between 86 mm boards and 4–5 mm between 135 mm boards at installation (WoodSolutions deck design guide)
• How much for a deck: a 20 m² deck needs about 140 lineal metres of 135 mm board or about 225 lineal metres of 86 mm, plus about 10% for offcuts
• Low decks: under 400 mm off the ground, WoodSolutions suggests 5–6 mm gaps and at least 40 mm between the deck and the house, for airflow
• Fixing: two fixings per board at every joist, at least 12 mm from edges and ends. Pre-drill this dense hardwood. Use stainless steel within 1 km of the coast or 1 m of a pool. See our decking screws
• Finishing: coat every face and cut end, ideally before fixing, then recoat at least once a year or as the oil maker directs (WoodSolutions); left bare, it weathers to silver-grey. Oils we stock: CUTEK CD50, Intergrain Universal Timber Oil or Sceney’s Timber Decking Oil
• At Greenhill: stocked at 170 Settlement Road, Thomastown, with pickup or delivery across Melbourne and regional Victoria. Compare species on our hardwood decking page.

Grey ironbark decking: sizes, lengths and prices

Sold in random lengths, cut to suit. Prices are our website prices on 14 October 2026, per lineal metre; a 20 m² deck needs about 140 lineal metres of 135 mm board or 225 of 86 mm, plus 10% for cuts.

What Grey ironbark decking is like

Grey ironbark, mainly Eucalyptus paniculata with E. drepanophylla and E. siderophloia, is the heaviest timber in our decking range at about 1,106 kg/m³ seasoned, and the hardest: WoodSolutions gives a seasoned hardness of 16 kN, roughly double Merbau. The colour is light grey to light chocolate with darker red and brown boards mixed through, and the grain is interlocked and dull rather than figured.

Durability is Class 1 both above ground and in the ground, which is why the same timber is sold as posts and bridge timber. The heartwood is termite resistant and the sapwood is not susceptible to lyctid borer, so there is little that needs to be cut out of a pack.

Where it suits

This is the board for decks that get punished: commercial walkways, pool surrounds, shaded decks that stay damp, anywhere a dropped tool or a dragged chair would mark a softer timber. The limit is bushfire: grey ironbark qualifies under the AS 3959 density rule for BAL-12.5 and BAL-19 but is not on the bushfire-resisting timber list, so it cannot be used for decking at BAL-29. For BAL-29 choose Spotted Gum, Blackbutt or Merbau.

Fixing and finishing

Pre-drill everything and expect to replace drill bits; at 16 kN the timber blunts tools quickly. Two stainless or Class 3 galvanised screws per board per joist, 450 mm joist centres, 4–5 mm gaps on the wide board. Being so dense it takes oil slowly, so apply thin coats of CUTEK Extreme CD50 or Intergrain Universal Timber Oil and wipe off the excess. Screws are in decking accessories.

The same timber for other jobs

• Grey Ironbark solid floorboards – 130 × 14 mm Feature grade in stock, other sizes ordered in
• Ironbark cladding
• Hardwood decking – all six species side by side

Compare the species

Our decking timber comparison puts hardness, durability, bushfire rating and price per metre for all six hardwoods on one page; Merbau decking is the budget alternative.

Questions we get asked

How much does ironbark decking cost?

On our website on 14 October 2026, 86 × 19 mm is $10.62 per lineal metre and 135 × 19 mm $15.90 per lineal metre, the same price per metre as Grey Box and below Blackbutt in the wide board.

Is ironbark the hardest decking timber?

Of the species we stock, yes: 16 kN seasoned hardness against 15 for Grey Box, 10.1 for Spotted Gum and 8.5 for Merbau.

Can I use it at BAL-29?

No. It is not on the AS 3959 bushfire-resisting timber list, so it stops at BAL-19 for decking, which it meets on density.

Is it red or grey?

Both come through in a pack: light grey and light chocolate boards with some darker red-brown ones. Oiled, the mix evens out.

Why is it harder to lay?

Weight and density. A 5.4 m 135 × 19 board is about 15 kg, every screw needs a pilot hole, and saw blades dull faster.

Pickup and delivery

Stocked at 170 Settlement Road, Thomastown, Mon–Fri 7 am–4:30 pm and Sat 9 am–1 pm. We pack and load it for you, or deliver across Melbourne and regional Victoria; delivery is quoted with the order. Call (03) 9465 9875 with your sizes and we will work out the lineal metres and the price.

Pick up from 170 Settlement Road, Thomastown. Stocked lines are usually ready the same day. Delivery across Melbourne and regional Victoria is quoted on the order; call (03) 9465 9875 for a price on your suburb.

All prices include GST. Flooring is priced per square metre, decking and dressed timber per lineal metre, framing and posts per length. Trade accounts get trade pricing on the site and at the counter: apply here.

Bring your room or deck sizes in, or call (03) 9465 9875, and we will work out boards, lengths, fixings and oil, with about 10% allowed for cuts.