">Timber Decking Types | Merbau, Pine, Hardwood - Softwoods

Types of Timber Decking

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Before we touch on the decking species that are available, it makes sense to briefly cover exactly what is required to build a deck for the uninitiated. Most timber decks are supported by strategically placed posts which are bolted to post shoes or stirrups above the ground. This ensures that the posts won’t decay and destabilise the deck. Attached to the top of the posts are bearers, which run parallel to each other along the deck. The bearers are usually the largest timbers in the deck and serve to stabilise and underpin the structure. Joists then run across the bearers and sit on top of them, normally at right angles to the bearers. Finally the decking boards are fixed to the top of the joists and run across the joists and in the same direction as the bearers. The calculation of the sizes of bearers and joists is a complicated process involving sophisticated engineering and many variables. For an overview please visit this decking blog post.

This simple decking structure can be amended in many ways to create elaborate decks that are suspended from the side of a home, have multiple levels or unusual shapes.

Softwoods Decks

The substructure of Softwoods decks is usually Treated Pine. We find that H3 Kiln Dried treated pine provides little to no movement, is resistant of rot and insect attack, and is also the most economical option. Our posts sit on hot dipped galvanised steel posts shoes (or stirrups) and we use galvanised bolts to further ensure no rusting will affect your structure. Bearers are bolted to posts and joists are secured to bearers using trip-l-grip or uni-tie brackets and galvanised nails. All of these measures have been developed over the years to ensure that a Softwoods deck is built to last.

Types of Timber Decking

The primary variable aside from size and shape of decks is the type of decking board that you use. Decking comes in many different species, both softwood (pine) and other hardwood decking species, offering variable strength, size and flexibility, as well as colour, grain and density. With these variables come different prices and performance. Softwoods provide a large range of decking options to ensure that we can provide you with what you want in a deck at a price that suits you.

Below is a brief description of the varieties of decking we specialise in, as well as some information about each. Each variety has ratings for Density, Toughness, Durability and Colour taken from a paper by the National Association of Forest Industries. The ratings are explained below:

  • Density Rating for seasoned timber is a measure of mass in kilograms per cubic metre. Density rating is a great indicator of the strength of the timber and serves as a good comparison between species. The higher the mass, the more dense the timber is.
    Toughness Rating is a measure of impact resistance or strength of the timber, measured in Newton metres but simplified to Low(up to 15) Medium (15 to 25) and High (25 and over)
  • Durability Class consists of four classes based on tests carried out on untreated heartwood. A score of 1 indicates high durability with the expectation of resistance to decay for over 40 years. Class 2 offers high durability with an expectancy of 15 to 40 years decay resistance. Class 3 is moderate durability with 7 to 15 years resistance and Class 4 is low durability with 1 to 7 years expected resistance. Please note also that the timbers tested are untreated and undried, as well as unpainted or stained. Once treated and stained timber can be expected to last for much longer than anticipated here, but these scores show well the variability and qualites of the differing species.
  • Colour is coded as below and gives an indication of the unstained natural colour of the timber.
    • W- White, Yellow, Pale Straw, Light Brown
    • P- Pink to Pink Brown
    • R- Light to Dark Red
    • B- Brown, Chocolate, Mottled or Streaky

ACQ Clear Treated Pine

ACQ Clear treated pine is a new product which offers the great colour and performance of treated pine decking without defects (knots) or green tinged CCA treatment to discolour it. Produced as a DAR (Dressed all round (meaning smooth on all sides)) decking board with a reeded (small ridges) top surface, ACQ treated pine has a density rating of 550, a toughness rating of L and a durability class of 1. Its colour varies from a Pale Straw to Yellow. As a softwood product, treated pine decking performs exceptionally well and is our highest selling decking product. It is also very economical, and comes in a variety of sizes and widths. It’s clear finish after treatment means that it takes stain exceptionally well and the treatment means that it is hard wearing and durable.


Merbau is an imported hardwood decking variety, originating from Indonesia. It is also a DAR decking board (which occasionally has a reeded surface on one face) and is available in 90mm wide boards as well as 140mm wide. Merbau is an exceptionally well performing decking board with a density rating of 850, a toughness rating of M and a durability class of 1 in above ground use. It is a deep red brown colour, and is subject to some initial tannin bleed when first unpacked.


Kapur is also imported hardwood decking, originating from Indonesia. It is a DAR decking board, with all four corners slightly pencil round. Kapur has a density rating of 750, a toughness rating of M, a durability class of 2 for above ground use and a colour of WPR, which is usually a light reddish brown colour which is a little pale. Kapur is a great value decking board that performs well and has a great grain and colour.


Ironbark is an Australian Eucalypt hardwood, selectively forested from NSW and QLD. Ironbark produces exceptionally hard wearing decking boards. The boards are a DAR product and have a density rating of 1100, a toughness rating of H, a durability class of 1. They vary in colour with a rating of WRB and usually have the appearance of light grey, red or a dark brown.

Spotted Gum

Spotted Gum is a selectively forested Australian hardwood from NSW and QLD. Spotted Gum decking is produced with a DAR finish. It is also very hard wearing with a density rating of 1100, a toughness rating of H and a durability class of 1 for above ground use. Spotted Gum boards are brown, and can range from a light to dark colour. They have a distinctive wavy pattern in the grain of the timber.

Tallow Wood

Tallow Wood is another variety of selectively forested Australian Eucalypt hardwood from South East Queensland. Tallow wood is also produced as a DAR board and has a density rating of 1000, a toughness rating of M and a durability class of 1. Tallow wood is generally a light coloured yellow brown.


Blackbutt is another selectively forested Australian Eucalypt hardwood. It is also sourced from NSW and QLD, and is produced as a DAR decking board. Blackbutt has a density rating of 900, a toughness rating of M, a durability class of 1 for above ground use and is a blonde or pale coloured hardwood.


Jarrah is also a selectively forested Australian Eucalypt hardwood. It is produced as a DAR decking board and is sourced from WA, Victoria and the Northern Territory. Jarrah decking has a density rating of 800, a toughness of L and a durability rating of 2. It is usually a vibrantly coloured red/brown decking board and makes for a very nice looking deck.

River Red

River Reds are yet another variety of Australian hardwood Eucalypt. Selectively logged from WA, NSW and QLD they are produced as a DAR decking board. River Reds have a density rating of 900, a toughness rating of L and are durability class 2. They have a great range of deep to light red and brown shades and provide great contrast and variability in a deck.

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