11 September 2026 · Composite deck maintenance

Composite Deck Board Gaps in Tamarin: Why Boards Buckle in Tropical Heat and How to Fix Them

Composite decking was sold as low-maintenance, and for many Tamarin villas and resort terraces that promise holds. But there is one issue that catches owners off guard more than any other: thermal expansion. In Mauritius, a composite board sitting in direct sun can reach surface temperatures above 60°C. When that heat builds up, the boards expand along their length. If the gaps are wrong, something has to give — and it is usually the board itself.

Why composite boards buckle

Unlike timber, composite expands mainly along its length rather than across its width. Manufacturers specify a minimum expansion gap at every board end — typically 5 to 8 mm, depending on brand and board length. When those gaps are absent, blocked by debris or filled with sealant, the expanding board has nowhere to go. It pushes against the adjacent board or the wall, and the pressure lifts or buckles the surface.

The problem is amplified on Tamarin rooftops and pool decks where reflected heat from tiles or water surrounds pushes surface temperatures even higher. A board that was fine in July can buckle in December when the sun angle changes and shade disappears.

How to spot the early signs

Walk the deck in the morning before it heats up. Look for board ends that are touching with no visible gap, boards that have lifted at the join, or a slight ridge where two boards press together. Listen for creaking or popping sounds as the deck warms — that is the sound of boards under compression.

Check the perimeter: where the deck meets a wall, pool coping or planter box, there should be a 10 mm clearance gap. If the boards are tight against the structure, they were installed without accounting for summer expansion.

Fixing buckled boards

For a single buckled board, the fix is straightforward. Remove the board, clean out the gap, cut 5 to 8 mm off the end if it has swollen, and refit it with the manufacturer’s clips at the correct spacing. Do not face-screw the board down to hold it flat — that prevents natural movement and will cause the next board along to buckle instead.

If multiple boards in a row are pressing, the entire run needs to come up and be relayed with consistent end gaps. This is common on decks where the installer ignored the manufacturer’s gap specification or butted boards end-to-end for aesthetic reasons. The repair cost is modest if the subframe is sound.

Preventing the problem on new installs

On a new Tamarin deck or a refurbishment, insist on three things: proper end gaps to the manufacturer’s spec, correct clip spacing that permits the board to slide, and a perimeter expansion allowance of 10 mm at walls and fixed structures. Do not let boards run tight to a glass balustrade channel or pool edge — the expansion will crack the seal or lift the channel.

For roofs and west-facing terraces at properties like Tamarina Golf Estate, choose a lighter board colour to reduce surface temperature and expansion range. Dark charcoal and walnut composites absorb more heat and expand more than silver-greys and sands.

When to call a professional

If only one or two boards are affected and the subframe is solid, a targeted repair is worth doing. If the buckling is widespread, the deck was likely laid without expansion gaps throughout — and a full relay is the only lasting fix. For more on diagnosing other composite problems, see our warping and fading guide and our Tamarin decking service.