Composite Decking Resources

Do’s and Don’t for Deck Installation

Advising your best interests. 

Please read the instructions fully before starting to install. Failure to install composite decking correctly will result in the deck becoming structurally unstable. A 10mm gap around the whole deck must be left for expansion and a 5mm gap between board ends.

1. DO this when installing. 

Here is  a list of what we advise you doing when installing your deck. All of this information is also available in our latest composite decking brochure. If you have any questions or queries regarding this information, please give us a call and we can help you resolve your issue.
List of things you should DO when Installing

Leave a 10mm Gap around the deck perimeter to allow for movement.

Ensure there is good air circulation around and under the whole deck.

Leave a 5mm Expansion Gap between board ends.

Double joist where board ends meet. Each board end should have its own clip and joist.

Use Steel installation kits for fixing to steel aluminium joists.

Use good quality joists or aluminium. Pre drill fascia boards before fixing.

Use recommended clips to secure boards to joists.

Pre Drill Steel joists to receive stainless steel screws.

Acclimatise boards to the environment for 3 days prior to installation.

Leave a natural fall to allow water to drain off boards.

Use locking clips to control even expansion & contraction along the length of the board.

20mm Maximum overhang from joist at deck edges with last fixing clip max 30mm from board end.

*Steel / Aluminium joists >2mm: A hole must be pre drilled in the joist and specific  Steel Joist Installation Kits must be used.

2. DO NOT do this when installing. 

We advise you to not do the following when installing your Whiteriver deck.
List of things you should NOT DO when Installing

Screw directly through boards and composite joists.

Store boards on solid or uneven surfaces.

Install in areas that have wall on all sides

Leave butt jointed and cut ends unsealed.

3. Bridging Supports

Bridging supports can be put in as required.

4. Structural Sound Subframe

A structurally sound sub frame must be installed ensuring there is no movement prior to fixing boards to the joists. A 1.66% (1:60) fall to allow water to drain and a minimum 100mm free air space between the boards and the ground beneath to allow sufficient airflow to prevent the build up of moisture is essential.

5. Clips and Fixings

Composite decking should only be installed using correct clips and fixings. Failure to do this will affect the structure of the deck as well as warranty. Never screw directly through the boards. Steel joists >2mm must be pre drilled and specific Steel Joist Installation Kits must be used.

Note: Due to the production process for Ultrashield decking board widths can vary slightly. Boards widths should be measured and matched accordingly.

6. Joists

Joists must be set to a maximum of 400mm centres for Portland and Ultrashield Eco (350mm Ultrashield Naturale and Wide Plank). This is to ensure stability and also to avoid warping and cracking of the deck boards. Note: 300mm are recommended for commercial installations.

7. Board Overhang

The overhang of the board should be a maximum of 20mm.

8. 5mm Gap For Expansion

Board ends butted together must be supported by separate joists and have a min 5mm gap for expansion, or use Aluminium Double Joist. Failure to do this may result in structural failure, swelling and warping. There should be a spacing gap left between the double joists to allow rainwater/debris to fall through the boards.
WRG Resources

Composite Decking Guide 

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Deck Preparation Avoid Installation errors