DuoDeck and DuoGroove Fitting Specifications

When fitting Duodeck much the same as any type of composite certain specifications must be adhered to. This will not only stop and failure in the deck boards but will also ensure that there is no bounce, flex and movement within the decking.

The Frame Supports:
The frame of composite deking whether you are using traditional timber carcassing or composite joists must be supported by a leg at every 1200mm centre in both directions. If, on uneven ground, the legs must be dug into the ground and concreted in using either a wet mix or pre-mix bag of Post Mix. We recommend either a 100x100mm post, concrete deck support or universal post cut to length. The depth of the supporting leg will differ depending on the height but should be a minimum of 350mm on low level decks.
If the deck is on top of an existing concrete pad then an Adjustable Joist Support must be used every 1000mm, these are fixed down to the concrete pad and are adjusted to give a level support.

The Framework:
The framework, again if using either traditional timber or Composite Joist, should have a maximum centre of 400mm, in most cases a 350mm span between is best practice. These are fixed to the support legs and should also be fitted with a structural screw such as a Timber-lock. If using composite joists, you must use our metal joist connectors, which allow for a bolted fixing and also keep the framework true and square.

The Deck Boards
The Deck boards, whether using DuoDeck or DuoGroove are run perpendicular to the framework underneath, they require a Tee Clip at every intersection with a joist. Composite will expand and contract over the varying seasons and therefore expansion gaps must be left if extending the run of boards in a linear direction. Boards can swell to as much as 10mm so it is important to allow for this, Gaps can always be covered with a corner strip at one end.

Facia Boards
Facia Boards must be pre-drilled with a countersink bit to prevent any cracking or splitting. The provide an attractive finish to all projects and cover the end of boards. For ease of fitting and best results they can be screwed into the joist below and therefore it avoids trying to fix into end grain of the boards.