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Installing Assured Hollow Composite Joists

Installing Composite Joists To Support Composite Decking

Assured Hollow Composite Joists require a solid concrete foundation to fix to. We advice creating a decline of 1% – 1.5% running away from a property acting as a drainage slope. Drainage holes or gutters can be placed in the concrete foundations if required.​

When installing composite joists ensure the area is clear and free of any obstacles including any cables and pipes.​

Laying The Composite Joists

Measure and cut composite joists where required.

Lay the composite joists into position leaving 300mm max intervals between each composite joist centre to centre. Leave 10mm expansion gaps close to a property and at joist butt joins.

Fix composite joists into place by drilling holes through the middle groove of each composite joist and into the solid foundation. Start at 80mm approx and then at 500mm approx intervals.

​Double joist where deck boards meet at butt joins allowing a 3mm gap between composite joists.

Why Choose Composite?

We are the UK's leading supplier of cost effective high quality composite decking, composite cladding and composite fencing for residential and commercial projects. Our products are made to the highest possible standard and go through rigorous and in depth testing phases before, during and after manufacture. Our forward thinking experienced team deliver efficiency, quality and the best customer care at all times providing customers a hassle free end to end solution when purchasing our products.

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If you have any questions regarding our Assured Composite® ranges then please give us a call on 0166 440 0140 or email us at

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