Timspec offers a range of decking options and there are a number of different criteria you should consider in your selecting a deck:

Species Selection:
We have a number of species available including Accoya wood, Jarrah, Kwila, Saligna and Vitex. While Kwila is the most popular, closely followed by Vitex, there are times where these are not suitable. The table below give a comparison of different benefits of our five major species.
Species Durability Movement
In Use 
Bleeding Length
Accoya wood Excellent 0.0 - 1.0% Minimal 2.4 - 4.8M (3.3M avg)
Jarrah High 5.0 - 7.5% Low 0.9 - 5.4M (2.4M avg)
Kwila High 1.5 - 3.0% High 1.8 - 5.4M (3.0M avg)
Saligna Medium 5.0 - 9.0% Low-medium 1.8 - 4.5M (2.7M avg)
Vitex High 2.0 - 4.0% Medium 1.5 - 3.6M (2.4M avg)

Profile Selection
There are generally two main profiles that we supply:

(also called Reeded One Face)
This profile was originally designed to be laid with the textured side facing down to help air circulation, however it is now generally laid textured side up to improve slip resistance (note that slip resistance is increased across the decking but decreased along the decking).

(also called Dressed Face)

This is by far the more popular profile because it gives a cleaner more modern look.
We can also machine to your custom profile, but you'll need to contact us for the details.

More about Slip Resistance
The Department of Building and Housing advises that decks not on the route to the main entrance do not require a slip resistance of 0.4 to meet the Building Code clause  D1 (Access Routes).
However any exposed timber decking on the route to the main entrance will probably need to have some form increased slip resistance, this is most easily achieved by either fixing a weatherproof matting to the timber or coating the timber with a sand/grit impregnated coating.

Refer to their website for more information:

Fastener Types:
Nails These are only suitable for decking up to 90 x 19mm because they lack the holding power for larger decking sizes.  You should always use annular grooved nails or else with time the swelling and shrinking nature of timber will push the nails upwards out of the deck.  Two nails should be driven through the decking (remember to pre-drill pilot holes) at each joist.  Where possible you should offset nails to minimise cracking and checking.
Screws These are suitable for decking boards up to a maximum size of 140x19mm, anything larger may require bolts.
Hidden fasteners These are relatively new to the marketplace and different brands work slightly different to each other but all are essentially fixed to the joists and attach to the side of the decking board.  The end result is a very modern clean-looking deck because no nail or screw heads are visible on the surface.

Expansion Gaps
Timbers commonly used in New Zealand vary enormously in term of stability (how much they shrink and swell). Three factors need to be considered in determining the gap between boards:
  • Moisture Content: Decking is supplied in a range of moisture contents to the New Zealand market, from near green to kiln dried. Generally speaking, a kiln dried will swell more than a green board.
  • Species: Kwila is a very stable species which does not shrink and swell a lot, however other species like Jarrah, Saligna, Greenheart, and others all shrink and swell a lot.
  • Size (width of board): Wider boards will shrink/swell more than narrower boards so require a larger expansion gap.
This table gives recommended expansion gaps for Timber Decking:
Species 90mm Wide 140mm Wide
Green /
Shipping Dry
Air Dried /
Kiln Dried
Green /
Shipping Dry
Air Dried /
Kiln Dried
Accoya wood N/A 2mm N/A 2mm
Jarrah Not recommended 5mm Not recommended Not recommended
Kwila 3mm 4mm Not recommended 6mm
Saligna Not recommended 5mm Not recommended Not recommended
Vitex 3mm 4mm Not recommended 6mm

For more information Download Hardwood Decking Brochure


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