Expert Decking Advice
Here are our most commonly asked questions.
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Good Design Practice for Decks
Most wood products undergo some degree of expansion and contraction with changes of weather and season. To compensate for these effects the following installation recommendations should be followed to ensure optimum performance of the deck.
Underside Ventilation
It is recommended that you build your deck a minimum of 300mm off the ground. This allows the deck to ‘breathe’ and will mitigate mould and mildew issues that occur as a result of humidity build up under the deck. If you are not able to have a 300mm gap under you deck then you should consider using a vapour barrier. We recommend a vapour barrier that allows water to pass through it such as weedmat.
Gap spacings
Between boards — minimum 3mm
Between boards and side of building — 12mm minimum
Board Ends — if KD allow 1-2mm gap.
Fall
Your deck should have adequate fall to stop pooling of surface water. We recommend a minimum of 10mm fall per lineal metre of deck.
Note: Decking shrinks and expands by varying amounts depending on the species. Laying kiln dried decking boards tight (ie with no gap) will not allow water to be shed from the deck.. If decking is green or wet after treatment then this is not such an issue as the deck will shrink as it dries out.

