Decking Subframe

Let’s be honest: a premium deck is only as good as the foundation beneath it. If you’re still using tanalized timber for your decking subframe, you’re taking a risk. Our composite decking subframe range is engineered specifically for the trade. Made from 100% recycled high-density plastic, it is completely resistant to rot, moisture, and ground contact decay. Whether you’re working with damp British clay or a low-clearance balcony, these joists will not warp, twist, or split.

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Showing 4 of 4 product(s)

Decking Subframe Joist (Black)

From £22.40

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Decking Subframe Post (Black)

From £21.25

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6mm Structural Wood Screws TX Star Flange Head Zinc

Structural Wood Screws TX Star Flange Head Zinc 6 X 100 mm (per 100)

£18.00 ev.VAT

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6mm Structural Wood Screws TX Star Countersunk Head

Structural Wood Screws CSK Head Zinc 6 X 100 mm (per 100)

£16.50 ev.VAT

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Why Every Pro Needs a Composite Decking Subframe

In this trade, your reputation depends on how the job looks and feels, five years after you leave the site. Traditional timber decking subframe joists are the leading cause of deck failures in the UK. Modern chemical treatments simply don’t withstand ground contact as well as older methods did. By switching to a composite decking subframe, you provide your clients with a structural guarantee that timber cannot match.

Technical Specs for the Installer

We understand that you need materials that align with your workflow. Our Arena range is designed for speed and reliability:

Low-Profile Solutions: We offer 47 x 97mm joists, the ideal “problem solver” for roof terraces or over-paving areas where clearance is limited.
Heavy-Duty Bearers: Our 50 x 120mm profiles provide exceptional rigidity for long spans and a wide surface area for securely fixing boards.
Uniformity: Every length is straight and true, no more wasting time searching through packs of timber to find a joist that isn’t bowed.

Pro Tip: Installation Efficiency

Fixings: These boards securely bite into structural wood screws or coach bolts for a permanent, vibration-free hold. There’s no risk of “screw pull” due to timber expansion.
Spacing: For standard residential builds, we recommend a spacing of 400mm between joists. For high-traffic commercial applications, reduce it to 300mm for a “rock-solid” feel underfoot.
Thermal Stability: Unlike wood, which absorbs moisture and expands, our composite material is incredibly stable, meaning your expansion gaps remain consistent throughout the year.

Build the Full System with LB Supplies

Don’t stop at the joists. Pair your composite decking subframe with our dedicated composite posts for a completely rot-proof structure from the ground up. At LB Supplies, we maintain a deep inventory of the Arena subframe system. We understand that you need gear on-site quickly, so order today for trade rates and fast UK delivery.