HOW TO ENSURE A LONG-LASTING WOODEN DECK

Step 1

Which wood is best?
A suitable decking timber should be able to cope with prolonged exposure to sun and rain. Heavy, durable hardwood is ideally suited for marine applications, but more affordable alternatives such as Saligna and CCA treated Pine can be used.

Step 2

What treatment does the wood need?
Heavy hardwood timbers do not need long-term preservative treatment – they can withstand rot and termite infestations. Decking treatments are often applied for cosmetic purposes and may not substantially increase the durability of the wood.

Step 3

Varnish or oil?
Varnish should be avoided for all external timber treatments as the varnish does not penetrate the timber, increasing the chance of degradation if exposed to sun and rain. Oil-based preservatives are preferable if a treatment is required, partly because maintenance is easier.

No treatment
Durable decking timber that is untreated will weather over time. The colour can either deepen or turn a silvery-white. This response is species-specific and does not reflect differences in durability.

Step 4

How do I space the slats?
Allow for a maximum 5mm gap between the slats for the best overall appearance of your deck. Remember – sound structure, correct attachment and correctly treated timber will keep maintenance costs low and ensure a long lifespan of your deck.

Step 5

Why has the wood moved since I built the deck?
All timber has a tendency to “move” when exposed to different climatic conditions. Heavy hardwoods in particular are virtually impossible to re-align once they start to twist or warp. So it is essential to attach decking correctly.

4 steps to prevent lifting or twisting

1. Use smooth-shank screws of non-rusting metal. Screws of at least 70mm (for 19mm decking slats) are recommended, longer for pine decking – a minimum of 50mm bind into bearer is required.
2. Holes must be drilled through the decking to accommodate the shank of the screw without the screw threads binding in the decking piece and without the screw being loose. The objective is for the screw to pull the decking firmly down onto the bearer – use clamps whilst screwing if possible.
3. A minimum of two attachment points for each decking section per bearer is recommended
4. Bearers should be 400mm apart centre-to-centre to avoid twisting or warping between them, and should not be more than 450mm apart.

Step 6

Sub-structure tips
The sub-structure of your deck is very important in determining its lifespan. Suitably treated timber such as creosote-or CCA-treated pine should be used. Remember that cut poles and bearers may expose untreated inner core timber. These exposed areas should be well treated to seal against rot and termites.

The design of your sub-structure should adequately cater for safety and load specifications.