Composite Decking Gap Inserts

Decking board gap inserts are a small component that make a big difference to the final look and performance of a decking system. Designed to fill or finish the gaps between decking boards.

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Thu, 28 Jul 2026

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This guide explains what decking board gap inserts are and how to install them for a long-lasting finish.

What are Decking Board Gap Inserts

A decking board gap insert is a narrow profile or strip that sits between adjacent decking boards.

Deck board gap inserts prevent valuables falling between decking boards and can be inserted with ease. A deck gap insert is a rigid strip of material, typically made from rubber, that sits between the deck boards.

Note: Our decking gap inserts only work on our Explorer range in conjunction with 6mm hidden fasteners.

How to Install Decking Gap Inserts

Step 1: Prepare the Decking Surface

Before fitting inserts, ensure:

  • All decking boards are fully installed and secured.

  • Board gaps are clean, dry and free from debris.

  • The structure is level and properly drained.

Step 2: Measure and Cut Inserts to Length

  • Measure each deck board run accurately.

  • Cut inserts to the required length using a fine-tooth saw or utility knife.

  • Smooth any sharp edges before installation.

Step 3: Position the Inserts

  1. Start from one end of the decking run.

  2. Align the insert directly above the gap between boards.

  3. For longer inserts, work in sections to maintain a straight fit.

  4. Ensure that each insert sits evenly along the full gap length without twisting or lifting.

Step 4: Install the Inserts

For Push-Fit Systems

  • Press the insert gently into the gap (use a rubber mallet if necessary).

  • Tap along the length until the insert locks securely in place.

  • Check that it sits flush with the board surface.

A Sleek and Functional Deck Finish

Decking board gap inserts are the perfect finishing touch for composite decking systems. Proper installation guarantees a clean, professional look that endures season after season.

EnviroBuild offers a complete range of decking accessories, including gap inserts, joists and adjustable decking pedestals, designed for long-lasting performance and effortless installation.