Decking Installation Guide

Park Deck and Standard 19mm Decking
86mm x 19mm
136mm x 19mm

  • Park Deck has a sawn faced wire brush surface and should be laid on joists and bearers of hardwood class 2 species or better at 450mm centers as per state regulations.
  • When using Park Deck we would recommend using Lanotec – Timber Seal Plus to promote a longer life of deck otherwise it can weather itself naturally.


Iron Deck and Peak Deck
136mm x 32mm
185mm x 32mm

Ironwood’s exclusive pre-greyed wharf-style Iron deck and Peak Deck should be laid on joists of hardwood class 2 species or better at 750mm – 900mm centers as per state regulations.

  • We would recommend to double joist for a good finish so there is no end grain splitting.
  • Double joists should be 50mm apart with a 50mm gap.
  • If using a 50mm joist on the side, double the gap to ensure a nice finish on the end joints.
  • We recommend stainless steel screws 14 gauge.
  • We recommend Lanotec – Timber Seal PLUS for longevity of the wood or weather it.
  • In high moisture environments we would recommend a 3mm gap between boards.
  • In a well ventilated area we would recommend a 1mm gap allowing for shrinkage naturally.
  • The top of the board is of a lower moisture content than the bottom of the board allowing it to cup reversely.

Important installation information.

  • When building an exterior deck, you should consult your states building codes and obtain any required building approvals before starting your project.
  • When purchasing and installing Ironwood decking it is important to check the installation area and apply the best practices required for installation. Customers should consider the below facts when installing decking boards.
  • Timber naturally absorbs and releases moisture depending on its environment, causing the timber to expand and contract therefore timber performs at its best when installed accordance to building codes.
  • Sub floor ventilation and drainage is very important when installing a deck. We recommend our decking boards be installed 400mm above ground, and that adequate ventilation be provided both above and below your deck.
  • When decking is installed below 400mm to the ground, Ironwood will not guarantee the consistent performance of any timber product in this environment.

Please refer to Australian Standard 1684 and the National Construction Codes before installing a deck.

On Site Handling

  • Ironwood decking is packaged with plastic wrapping designed to protect the product during transportation only. On site the product should be stored in a cool, dry area, away from the elements or well covered, stored at least 100mm off ground by timber gluts. We do not recommend the storage of our decking product outside, exposed to weather as this may affect its integrity before installation.

Decking Installation

  • Ironwood decking is a product designed to be installed onto bearers and joists and the standards for these products is outlined in the Australian Standard 1684: Residential Timber – Framed Construction and AS1720: Timber Structures – Design Methods.
  • However we recommend Class 2 durability or better.
  • These design methods are based around the installation of the product in a residential application, not a commercial application, therefore any commercial application may require additional design support and a change to the installation requirements.

Installation Preparation

  • Industry standards indicate a 15% waste factor to be considered when measuring the required decking. The surface below the timber deck should be clear of weeds, other debris and most certainly, moisture pooling. Good site preparation is essential to ensure the integrity of your deck. It is an Ironwood requirement that you gain suitable ventilation and drainage beneath the deck that prevents the pooling and build up.

Installation Methods and Requirements

Ironwood decking installation methods are rigorous and need to be adhered to in order to ensure the integrity of the timber is maintained and the life span of the decks is maximized.

Prior to installation of the decking boards, Ironwood recommends all sides of the board be coated including end sealing ,we recommend the timber is sealed with Lanotec – Timber Seal Plus protectant.

Ironwood recommends timber decks be placed 400mm above ground and will not warrant decks close to ground.

In this process, Ironwood requires:

  • All boards be checked prior to installation to ensure their integrity has not been compromised during delivery or site storage; warping and milling should be assessed before installation.
  • Adequate ventilation to be provided to the underside of the deck. Insufficient ventilation typically leads to warping and other timber irregularities.
  • Good surface drainage so water does not pool below the deck.
  • Where possible, access to be made available to support the maintenance of the timber deck.
  • Residential joist span to be 450mm centre to centre unless Iron Deck and Peak Deck.
  • 3-5mm gap between boards for decking boards.
  • That cutting and shaving metal objects on a timber deck be avoided as this will often result in black spotting.

For Extreme Conditions:

Ironwood does not recommend that our timber boards be placed below 400mm from the ground or in extreme conditions as previously mentioned, but there are a number of practices you can use to assist the timber’s performance in this application:

  • Ensure excellent drainage to prevent water/moisture from pooling.
  • The use of plastic membrane on the surface below the deck to assist drainage and prevent the pooling moisture.


Before fixing and for maximum serviceability and protection against weathering, Ironwood decking should be fully sealed as per specifications previously mentioned.  All bolts, screw, framing anchors and other hardware are required to be hot tip galvanised or stainless steel.

Electroplated fasteners are not recommended due to the early breakdown of the plating.

Each board 86mm – 185mm should be fixed at every joint crossing with two screws.  Screws should be located at least 12mm from the board edges.

Due to the density of Ironwood’s decking products, we recommend pre-drilling before installing screws.

Product: Ironwood decking products (all species)
Grade: Standard and Better
Thickness: 19mm, 32mm
Max Joist Span: 450mm to 900mm for 32mm
Screw Requirements: For decking boards 19mm thick a screw length of 50mm is required.  Decking boards 32mm thick require a screw length of 65mm plus.  We recommend 316 grade stainless steel screws.

Please note, it is important to regularly check and maintain fixings to ensure the performance of the decking structure.

Coating and Oil Recommendations:

refer to

As previously mentioned, any application of coatings should be applied in accordance with the manufacturer’s recommendations.  In addition to this, Ironwood recommend oil-based products with mould inhibitors, preferably light-coloured pigments, and that the oil contains as a minimum:

  • 10% copper naphthenate in a light organic solvent
  • 20% zinc naphthenate in a light organic solvent
  • All sides of the board covered prior to installation
  • End sealing when boards are cut, pre-installation

Maintenance of an Ironwood Deck:

The long-term performance and integrity of an Ironwood deck is dependent on the consistent maintenance and care.  Regular and effective maintenance is key, especially when the product is exposed to weather or harsh conditions.

Typically, we recommend maintaining a decking every 6-12 months, however the frequency of maintenance is dependent on the type and quality of product used and the weather exposure of the deck.  For highly exposed decks, maintenance might be required more regularly than every 6 months.  Please follow the maintenance guide of the coating manufacturer.

Before re-coating, the deck and gaps between the boards should be thoroughly cleaned, especially over the joist areas (areas where debris may build up).  Re-coating should be carried out in accordance with the coating manufacturer’s recommendations.

Ironwood suggests that the storage of pot plants and landscape structures direct on a deck be avoided.  It is recommended these items be placed in drip dry trays and in good ventilation areas.  Where possible decks should be cleaned by broom or blower, rather than by hosing.

Bushfire Area Information:

Please note other installation factors my need to be considered including the construction of timber decks in a bushfire prone area (AS3959), and Dead and Live Load requirements (AS1170).

Some Ironwood species are BAL 29 rated and suitable for bushfire prone areas.  We recommend the use of Ironwood Iron decking and Peak decking in these areas.  We also recommend that local council requirements be understood before installation and adhered to during installation.

Installing Around Pools or Near Sea Water:

If installing Ironwood decking around pools or near sea water; it is important to note the following things:

  • Timber boards need to be well coated on all four sides before installation to help minimise cupping.
  • Moisture uptake by timber is likely when installing within 1.5 metres of a pool or near sea water.
  • Fixings should be assessed and well maintained.  Check fixing manufacture’s guide for details.