Choice of Timber

What Should I look for when building a deck?

Timber should be of specific moisture content to suit your local environment. Local authorities can inform you of this information.

Kiln Drying – Provides consistency, stabilises the timber, reduces twisting, when a supplier goes to the trouble of kiln drying your timber it is more expensive but the end result is well worth the cost. Deck-Max™ believes that….

Kiln Drying of the decking, stablises the timber and reduces twisting. This extra process will add cost to the material however does minimise a lot of the typical problems of timber that is not Kiln Dried.

Deck-Max merbau decking
  • Use Hardwood timbers that are Durability class 1 and 2 above ground. All Deck-Max™ hardwood decking meets this criteria.

  • Bamboo and Composite decking materials are in a different class however the materials made by Deck-Max™ meet all standards.

  • Decking boards should be seasoned to the requirements of the applicable Australian Standard (i.e. Hardwood 10% to 18%, ) Note: TQL recommends a maximum MC of 15% for residential decking.

  • Refer to your local ambient city guide – this will provide you with the ambient (the local city moisture content recommended) moisture content recommended in the timber before laying, preferably before delivery. Your decking supplier can provide you with:

    • Local ambient moisture content for your city / town / region

    • Moisture content of the material at store level. Note: it will change in transit and when it arrives on site at which time it will achieve the ambient moisture content for your area.

  • Grading of Wood is based on Australian standards of AS 2796, that will provide you with what is referred to as Standard and Better in reference to outdoor decking. This will provide you with some inconsistencies of colour, knots, holes and all the natural attributes of hardwood.

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Decking should not be installed too close to ground

  • (meaning that if the natural ground is moist and can affect the moisture content of the underside of the board then you are installing too close to ground).

  • 400mm off ground or less you can run into trouble.

  • Consider if the deck is to be fully exposed to the weather or not. Then you must consider the following including what gap setting you will use.


Important when trying to fix over a concrete base or the natural ground does not flow away from the house.

  • When fixing over concrete be sure to run the hose over the surface to be sure the water runs away and does not pond.

  • Excavate the ground to be sure that any water will run away from under the deck and does not retain moisture.

  • Refer to Technical Data Sheet 13 by timber Queensland.

  • After excavation lay down geofabric or plastic sheet then cover with course to fine rock or gravel over and around the post supports prior to laying the decking boards.

Air Flow Ventilation

This ensures that the air flow over and under the deck keeps the top side and the underside of the decking boards at consistent moisture content.

  • Do not close in around a deck – this blocks air flow and will cause the decking boards to cup and twist.

  • Do not build up your gardens to the same level as the deck – this will block the air flow and cause damage to decking boards.

Gap settings for decking boards

Gap settings have always been decided by the installer / carpenter to suit the environment etc.

  • If you are in a fire rated zone – Deck-Max™ has the 5mm biscuit to use as standard gap set and is also fire rated.

  • All Deck-Max™ Biscuits have the capacity to be set from 3mm gap out to 6 or 7mm wide.

  • A wider gap setting should be selected when installing close to ground. Deck-Max™ 5 mm is ideal.

  • Choose the substructure of choice – Pine [A.C.Q. & C.C.A.] – Hardwood – Metal

Deck-Max ™ DECKING can only be used in conjunction with the Deck-Max™ ”Pro Biscuit”. This biscuit is designed to the profile.

  • Deck-Max ™ decking and fixings are protected by patents and licenses.

  • Profile – The unique profile is engineered for strength, gap settings and ease of installation.

  • Waste – When using Deck-Max™ decking with the End Match profile your waste savings are as high as 75% saving.

  • Fast installation – Our contractors lay up to 45 sq.m. a day with this very high quality finish.

*Note: All measurements and quantities are subject to your order quantities and the timber supplier takes no responsibility for your quantities.

Bamboo decking sustainable air VentilationDecking gap settings
Deck-Max decking preparation


  • Deck-Max™ “Pro” Biscuit – Only buy board from Deck-Max™ licensed timber supplier with the correct specifications.

  • The Original Biscuit – This can also be pre grooved AND/OR the board is prepared by preparing a lateral cut to both sides with a standard biscuit cutter. Run a test sample cut prior to preparation of timber.

  • An exterior construction adhesive Bostik ULTRASET must be laid on top of the joist prior to fixing the board.

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  • The moisture content of a floor must be assessed, because if the moisture content is outside allowable limits, there is a greater probability of cupping, crowning or twisting. Where possible, moisture readings should be checked and recorded on both the top and bottom surfaces and these readings should be checked and recorded on both the top and bottom surfaces and these readings should vary by less than 3%. Moisture readings should be taken and recorded in at least four places in each deck area and should include areas near walls as well as the centre of each deck. A variance of less than 1% between readings is desired and the mean of readings should correlate to the mean EMC for the situation. Where the recent history of the boards or the acclimatisation practices are unknown, the moisture contents of the boards should be compared to that of other timber components used in the same building, eg: joists, bearers, skirting, door frames, etc. This procedure can also be used to aid in establishing the moisture content of timbers such as brush box, for which moisture readings made with electrical resistance metres can be unreliable due to extractives contained in the timbers which can influence conductivity.

  • Many dwellings are bricked in underneath and a lack of sufficient ventilation can result in high humidities in the sub-deck space. This may result in excessive expansion and cupping of floor boards.

Deck-Max composite decking Brisbane and Australia wode

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