1. Product & Storage - Use Sunrays Timber WPC hollow decking boards and approved clips/screws only. Store boards flat, fully supported, in a shaded and well-ventilated area. Avoid leaving uninstalled boards in direct hot sun. Check color, profile, and length before cutting or fixing.
2. Subframe & Site Preparation - Surface: Suitable over concrete slab, pavers, or footings with bearers/joists. Substrate must be solid, stable, and free-draining (no standing water). Fall (Slope): Build a consistent fall away from buildings of approx. 1:100 to 1:80 (10–12.5 mm per meter). Joist Spacing (Centre-to-Centre): Residential decks: max 450 mm centres (unless otherwise specified). Add blocking/noggins at board joins, perimeters, and stairs. Ventilation & Clearance: Maintain minimum 80–100 mm clearance from ground to underside of boards. Allow air circulation under and around the deck. Do not fully box-in the subframe.
3. Expansion Gaps - Boards expand and contract mainly along their length. Never butt boards tight. End gaps between boards (approximate guide): Boards 2.2–3.0 m: leave 3–5 mm. Boards around 5.4 m: leave 5–8 mm. Between boards and walls/solid structures: leave 10–15 mm. Side gap between adjacent boards is created by the Sunrays hidden clip system (typically 4–6 mm). Install in normal ambient temperature where possible and follow any project-specific Sunrays recommendations.
4. Fixing System – Sunrays Hidden Clips
4.1 First (Starter) Board - Mark a straight line along the first joist using a string line or laser. Fix Sunrays starter clips along that joist, in line and firmly screwed. Engage the first board’s groove into the starter clips. Confirm the board is straight and square – this sets the whole deck.
4.2 Field Boards - Insert Sunrays standard hidden clips in the groove of the laid board at each joist. Slide the next board’s groove onto the same clips. Tap boards gently together with a rubber mallet. Tighten clip screws firmly, but do not over-tighten; boards must still move for expansion.
4.3 Board Joins - Use double joists or wider joists under board ends so each board end is fully supported. Maintain the specified end gap (typically 5–8 mm). Stagger board joins where possible for a more natural appearance and better load distribution. Do not fix through the thin hollow walls of the board. Use the approved Sunrays groove and clip system or any direct-fix method specifically stated for the product.
5. Cutting, Edges & Finishing - Use a fine-tooth carbide-tipped blade for clean cuts. Support boards fully while cutting and keep edges square. Lightly sand cut edges if required. Hollow Ends & Perimeter: Fit Sunrays end caps into exposed hollow ends (use suitable exterior adhesive if recommended), or install fascia/edge boards to conceal board ends and framing. Maintain small ventilation gaps behind fascia to keep airflow under the deck.
6. Cleaning & Maintenance - Sweep regularly to remove leaves, dirt, and debris from gaps. Wash with mild detergent and water using a soft broom or brush. For stubborn marks, use a non-solvent cleaner suitable for WPC surfaces. If using a pressure washer, keep the nozzle at a safe distance and use moderate pressure only.
7. Common Errors to Avoid - Exceeding recommended joist spacing (can cause bounce or sagging). No fall or poor drainage, leading to ponding and staining. Forgetting expansion gaps, causing boards to push and buckle. Over-tightening fixing clips so boards cannot move. Blocking ventilation with cladding or stored items under the deck.
8. Warranty Note - Correct installation in accordance with this guide and current Sunrays Timber documentation is essential for warranty coverage. Retain this guide, your purchase invoice, and any site drawings or photos as proof of installation method.