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We love to hear from you any feedback or questions regarding BiForm solid composite decking solutions. 

International Customers
+64 9 636 3511

New Zealand
09 636 3511/  0800 449 274

Unit 8, 69 Captain Springs Road, Onehunga
New Zealand

09 636 3511

Eco-friendly solid composite decking solutions based in New Zealand.



Learn about installing BiForm composite decking products by reading through the information below.

Installation & Specifications of BiForm Decks

Learn about installing BiForm composite decking products by reading through the information below or print off a copy of our installation and specifications guide below.


WPC (Wood Plastic Composite) decking needs to be transported flat – it can’t be tied on an angle, for example on a Ute. Also needs to be on edge, (the narrow edge horizontal and the flat edge vertical).


If working parallel to the building leave a 12mm gap between the building and the first board.Secure the first board using anti-mushrooming Composite Screws. Continue to fix the boards using the concealed fixing clip and screw on each joist. For ease of installation, don't over tighten the fixing screw as this can make the next board difficult to slide into place. You can tighten the screw later if required. Any screws or nails should be located no less than 25mm from the edge or end of the board.

Temperature Expansion and Contraction

The composite decking expands and contracts lengthways due to the temperature changes during the day. Before cutting, the temperature of each board should be assessed. Hot boards will shrink as they cool and cool boards will expand as they heat up. The boards should be laid out in the area they will be installed and allowed to acclimatize. If installing during the heat of the day the boards can be cooled with water from a garden hose to avoid movement after installation - do not leave expansion gaps.

To reduce the effects of movement of long boards over 4m the preferred method of installation is:

  • A picture frame design to encase the boards
  • A breaker board at right angles to the deck boards instead of staggered joins
  • Avoid butt joins. 

Safety and Tools

Usual safety precautions used when working with wood should be applied when working with BiForm composite decking.

BiForm composite decking can be drilled, sawn, fastened and routed with normal wood working tools.

Breaker Boards

Recommended after each 4.85m length. These boards run at a 90 degree angle to the deck boards and need to be attached with composite screws to the extra joists below.


View the care and maintenance instructions


BiForm composite decking requires joists at 400 and the deck should have a fall of 1mm per meter of decking along the long edge. For timber joists we reccomend kiln dried, uniform height and thickness MSG8 joists. Ground clearance - over damp ground with little ventilation 300mm is required. However it can be used over sealed substrates such as concrete or a waterproof membrane with as little as 50mm ground clearance.

Overhang on the ends or sides of the deck should be no more than 50mm.

Please note lengths are 4850mm however up to 5mm variation can occur, please dock to uniform length on site.

Using BiForm concealed fixings ensures the required 5mm space between boards.

If using the preferred design of picture frame and or breaker boards, double joists will be required.

If your deck is situated on a second story and will be exposed to strong winds, applying wind break cloth over the joists, before installing the deck will reduce the effects of any wind noise later. 

Storage and Handling

BiForm Decks composite decking should be stored flat, on edge, off the ground and under shelter away from direct sunlight. The boards require nine to ten supports along the length of the board.

Orientation/ Direction of Boards

Lay the boards at the same orientation as they are removed from the pack. If a board is turned and laid in the opposite direction from the others there may be a texture or colour change which becomes apparent after the weathering process.

Staggered Butt Joins

These are not recommended, but may be used for surface fixed edge boards or smaller decks (3m or less).

Fixing Base Boards

Fix using the anit-mushrooming composite screws.

When fixing base boards try to do so when it has been in the sun and expanded to its maximum. Fixings should be every 300mm to keep the base board stable.