Sale!

Greybox Decking

Starting From Just $15.90

Request a Quote
03 9465 9875

Width

Clear your selection

SKU: GHT-1929 Categories: Decking, Timber Decking Brand: Greenhill Timbers Product Brand: Green Hill Timbers Janka Rating: 15

Price by L/M

Open a 30 day trade account

Grey Box decking in 86 × 19 mm and 135 × 19 mm: one of the hardest, most durable Australian decking timbers, with Janka hardness 15 kN and Class 1 durability both above ground and in-ground, rated for bushfire decking up to BAL-19.

Sizes: 86 × 19 mm and 135 × 19 mm in random lengths
Timber: Grey Box (Eucalyptus moluccana), grown from Jervis Bay in NSW to the Atherton Tableland; usually pale brown, sometimes yellowish; about 1105 kg/m³
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
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.

The Greenhill Timbers Advantage

✓Nationwide Delivery Network – Fast reliable delivery across Australia
✓Price Match Guarantee – Cheapest Prices Guaranteed
✓Quality Graded Products You Can Trust
✓Melbourne Warehouse & Showroom – Visit Us Today

Product Description

Grey Box decking: sizes, lengths and prices

Size	Lengths	Price	Availability
135 × 19 mm	Random length	$15.90 per lineal metre	in stock
86 × 19 mm	Random length	call for price	ordered in

Sold in random lengths, cut to suit. The 86 × 19 mm board is ordered in; call for a price. 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, plus 10% for cuts.

What Grey Box decking is like

Grey Box, Eucalyptus moluccana, grows from Jervis Bay in NSW up to the Atherton Tableland and is one of the hardest Australian decking timbers: WoodSolutions gives a seasoned hardness of 15 kN at about 1,105 kg/m³, with durability Class 1 above ground and in the ground and a termite-resistant heartwood. The boards are pale yellowish-brown to light brown, plainer and more even than Spotted Gum, with a fine interlocked grain.

The sapwood is susceptible to lyctid borer, so decking is cut from heartwood. It moves less than Silvertop Ash and Blackbutt once seasoned, which helps a wide deck stay flat.

Where it suits

Choose Grey Box where ironbark would do the job but you want a lighter colour: pool decks, commercial areas and decks that stay damp. Like ironbark it qualifies for BAL-12.5 and BAL-19 under the AS 3959 density rule but is not on the bushfire-resisting timber list, so it cannot be used for decking at BAL-29; for that, choose Spotted Gum, Blackbutt or Merbau.

Fixing and finishing

Pre-drill, two stainless or Class 3 galvanised screws per board per joist, 450 mm joist centres, 4–5 mm gaps on the 135 mm board. It takes oil slowly, so brush thin coats of CUTEK Extreme CD50 or Intergrain Universal Timber Oil and wipe off what does not soak in. Screws and joist tape are in decking accessories.

The same timber for other jobs

Grey ironbark decking – the other 15–16 kN board, darker in colour
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 Grey Box decking cost?

On our website on 14 October 2026, 135 × 19 mm is $15.90 per lineal metre. The 86 × 19 mm board is ordered in; call for a price.

Grey Box or ironbark?

Almost the same hardness and durability. Grey Box is paler and more even in colour; ironbark runs grey to chocolate with red boards. Neither can be used at BAL-29.

Is it termite resistant?

The heartwood is, in the WoodSolutions and Queensland Government tables. Treat the subframe anyway if it is in contact with the ground.

Does it bleed?

Less than Merbau and Blackbutt. Wash it down before the first oil as with any hardwood.

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.

Reviews (0)

Reviews

There are no reviews yet.

Be the first to review “Greybox Decking”

Janka Rating

Greybox Decking — Janka hardness: 15 kN

What Is the Janka Rating?

The Janka rating is a way to measure how hard a timber is, specifically, how much force it takes to push a small steel ball halfway into the wood. The number you get is shown in kilonewtons (kN). A higher Janka score means a harder, more durable timber. Builders and floor installers use it to work out which timbers hold up better in busy areas.

Here’s a rough guide to how some timbers sit on the scale:

Brazilian Walnut – around 16.0 kN
Spotted Gum – roughly 11.0 kN
Tasmanian Oak – about 5.5 kN
Radiata Pine – close to 3.0 kN

Keep in mind: these values can vary depending on moisture content and grain direction.

It's One Part of the Decision

Hardness is useful to know, but it’s just one factor. Janka doesn’t tell you how a timber reacts to heat or humidity, how stable it is, or how easy it is to cut and install.

Some of the hardest woods can be difficult to work with. Others, even if softer, might be more stable or forgiving on-site.

At Greenhill Timbers, we look at the whole picture, not just the numbers. All our timbers are structurally graded and covered by a 25-year guarantee. We'll help you pick something that works for your project, not just on paper.

Delivery Options

Melbourne-Wide Delivery

We carefully prepare your order and organise pick-up or delivery that suits your schedule, ensuring your satisfaction when you choose to purchase from us. If you're located in Melbourne and its surrounding areas, you can collect your order from our Thomastown Showroom at 170 Settlement Road. Otherwise, we can facilitate delivery by leveraging our strong partnerships with various sub-contractors to get you the most competitive delivery rate and suitable time frame. For more information, get in touch with us.

Why Choose Us

Get Your Timber Packed

We pack, wrap and load your products into your vehicle on-site. As a Green Hill customer, you won’t have to pack your timber or lug it into your vehicle after you’ve purchased it.

One Stop Shop

We are a one-stop shop for all your timber needs. Get dozens of types of wood, both imported and local, and the right cuts for your decking, flooring, cladding and fencing projects.

Competitive Pricing

In most cases, we can help you save hundreds or even thousands of dollars on the same materials compared to other timber suppliers.

Expert Staff

Our expert staff will assist you in finding the perfect timber to match your projects based on a relaxed chat to find what you need.

Transparent Quotes

We give you the whole picture when we quote you. So you can avoid any nasty surprises down the line.