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Waterproof Deck System – DryJoist

Waterproof Deck System – DryJoist

Structural Deck Drainage System

NexGEN DryJoist is a structural deck drainage system that provides the structure of the deck, a waterproof solution and a finished ceiling with a traditional bead board appearance, all in one step! DryJoist is easy to handle and cut and can be installed in any weather conditions, wet or dry. It is perfect for balconies and decks for both residential and commercial applications.

Built-in Waterproof Solution

Replacing traditional wooden joists while creating a 100% dry space in the area below. It’s a single system, integrative design that eliminates add-on gutter systems, waterproofing membranes or drainage substructures.

Three products in One!

Waterproof Deck System – DryJoist


Waterproof Substructure – Deck drain allows for 100% waterproof area underneath

Waterproof Deck System – DryJoist


Joist System for Decking – Low profile structural system will span up to 1.8metres long

Waterproof Deck System – DryJoist


Finished Ceiling Underneath – Powdercoated beadboard finished soffit ceiling


The cross-sectional profile of DryJoist is such that it is 50mm in height with two board widths, 100mm (multi-joist) or 150mm (main-joist).

Once installed, each board acts as a box gutter; therefore, only a slight fall is required for water to be effectively shed/diverted in a given direction (nominally, 1 in 100 is recommended for effective water shedding).


We supply DryJoist waterproof deck system on a job-by-job basis; hence the product is customised to every project and provided as a complete package. This dramatically reduces installation time and product wastage.

In the package, everything required for the installation would be provided: DryJoist Boards, Ledger Flashing, Header Flashing, Trim, Fixings, etc.

NB: the typical lead time is 12-18 weeks from the order date.

(If this lead time is too lengthy and your project does not involve a habitable space, consider using our Select capped composite boards and Weatherstrip. These products are readily available here in Australia)


DryJoist waterproof deck system is an extruded marine-grade aluminium product that, when laid, creates a structurally sound, waterproof subframe system that will never rot, warp, crack, rust, or be prone to termites – just like our timber composite decking.

DryJoist is also lightweight and durable, which reduces overall building costs as the associated support frame system requirements are considerably reduced compared to alternative products.

DryJoist will comfortably span 1,800mm under all regular commercial applications or load conditions (5 kPa).

NexGEN Decking


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