Tools you’ll need

Materials checklist

• ECOGEN Deck WPC boards — 138 × 22mm × 5.4m (calculate quantity below)
• Hidden fastener clips — 1 clip per board end + intermediate supports
• Stainless steel screws — for securing clips to joists
• Fascia boards — Co-Ex, 3D or Eco fascia to finish perimeter edges
• Treated pine or steel frame joists — H4 treated for in-ground contact areas
• Post and bearer materials — as required for subframe height
• End caps — to seal board ends (optional but recommended)

How much decking do you need?

Formula: Deck area (m²) ÷ board area (0.138m × 5.4m = 0.745m²) × 1.08 (waste factor). Round up to the nearest board.

WPC composite boards require a solid, level subframe. Unlike timber, WPC boards have minimal flex, so an uneven or poorly spaced frame will show through as an uneven surface.

Joist spacing

Frame must be:

• Level — check with a long spirit level; any high or low spots will transfer through the boards
• Square — measure diagonals before securing; out-of-square frame = out-of-square deck
• Ventilated — leave adequate airflow beneath the deck to prevent moisture build-up under boards
• Drainage slope — minimum 1:100 fall away from the house for water runoff

Before cutting a single board, plan your layout. This saves waste and ensures an even appearance on both sides of the deck.

• Determine board direction — boards typically run parallel to the long side of the deck or toward the primary view. Diagonal layouts are also possible (requires 300mm joist centres).
• Calculate cut boards — divide deck width by board width (138mm + gap). If the last board requires a cut narrower than 50mm, adjust the starting position so both first and last boards are equal.
• Mark your starting line — snap a chalk line parallel to the house wall (or your chosen start edge) to keep rows straight.
• Expansion gap allowance — WPC boards expand and contract with temperature. Leave 5–8mm gap at all fixed structures (walls, posts, steps). Board-to-board gaps are managed by the clip system.
• Check board lengths vs deck length — 5.4m boards. If your deck run exceeds 5.4m, plan board end joints over a joist and stagger the joins on alternate rows.

The first board sets the alignment for the entire deck. Take your time here — a crooked starter board means a crooked deck.

• Position the first board — align the outer edge with your chalk line. Maintain 5–8mm gap from any wall or fixed edge.
• Secure with face screws at the outer edge — the outer edge of the starter board is face-screwed directly into the joist. These screws will be hidden by the fascia board.
• Insert first hidden clip — slot the clip into the groove on the inner edge of the starter board. Drive the clip screw down into the joist at 45°.
• Check alignment — measure from both ends before securing further. Adjust if needed; it’s much easier to correct at the start than after 10 boards are down.

• Slide each board into the previous clip — the groove on the board engages with the raised clip from the previous row. Press firmly along the length to seat fully.
• Tap to seat if needed — use a rubber mallet and a scrap piece of board to protect the groove. Never strike the board edge directly.
• Insert new clips on the free edge — clip into the groove on the new board’s free side, screw down into each joist. This fastens the current board and spaces the next.
• Check straightness every 4–5 boards — measure from a reference line. If boards are drifting, adjust the clip position slightly on the next row.
• Board end joints — if joining boards end-to-end, centre the join over a joist. Leave a 3–5mm gap between board ends for drainage and expansion. Stagger joins on alternate rows by at least 1 joist bay.
• Cut boards to length — use a fine-tooth circular saw blade. Cut with the face side down to reduce chipping. Mark with a square for clean 90° cuts.

Last board

The final board will need to be face-screwed on its outer edge (like the starter board). Use 50mm stainless steel screws, pre-drill to avoid splitting, and countersink so the screw sits flush. These screws will be covered by the fascia board.

Fascia boards

ECOGEN Deck matching fascia boards finish the perimeter edges and hide all face screws. Three fascia options available to match your decking range:

Fascia boards are face-fixed to the perimeter joist or rim board using 50mm stainless screws, pre-drilled and countersunk. Colour-match screws where visible.

End caps

Fit end caps to all exposed board ends to prevent moisture ingress and improve the finished appearance. Tap end caps in with a rubber mallet — no adhesive required on most cap types.

One of the main advantages of ECOGEN Deck WPC boards over timber is minimal maintenance. No oiling, no sealing, no repainting.

• Routine sweeping — sweep away leaves and debris regularly. Organic material left sitting on composite decking can stain if left for extended periods.
• Wash twice yearly — hose down with water and a soft brush. For stubborn marks, a diluted household detergent is sufficient.
• Avoid abrasive cleaners — do not use wire brushes, bleach, or solvent-based cleaners. These can damage the co-extrusion surface layer.
• Check frame annually — inspect timber joists and bearers each year for any signs of moisture or movement. WPC boards are permanent but timber subframes need monitoring.
• Furniture pads — use rubber or felt pads under outdoor furniture legs to prevent scuff marks on the board surface.
• Do not paint or stain — ECOGEN Deck co-extrusion boards have a factory colour finish engineered to last 25+ years. Painting over them voids the warranty.