Installing composite decking might look complicated, but with the right preparation and a few essential tools, you can transform your outdoor space in just a weekend.
This guide walks you through everything you need to know, from preparing the base to adding those finishing touches, using the same principles we follow for the Patio Store Composite Decking Range
Before You Begin
Before installation, unpack your decking boards and store them flat outdoors for at least 24 hours. This allows them to acclimatise to local conditions.
Check you have:
- A solid, free-draining base
- If your design includes posts or balustrades, install these first using Composite Metal Post Bases
- Good airflow under the decking (minimum 100mm clearance)
- A slight fall of around 5% to allow water drainage away from the property
Tip: Avoid installing below 0°C, composite decking can expand and contract slightly with temperature.
Tools You’ll Need
Everything can be installed with standard DIY tools:
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Tape measure and pencil
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Electric drill and screwdriver bits
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Level and square
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Circular or handsaw
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Joists and fixings
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Hidden fixing clips and starter clips
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Fascia trim and finishing angles
Step-by-Step Installation Guide
Step 1: Plan and Prepare Your Subframe
Decide the layout and direction of your decking boards, whether straight, diagonal, or chevron. Ensure joists are spaced 400mm apart (300mm for commercial use), supported on a level, stable base. Leave a 10mm perimeter gap around all fixed edges, walls, or posts for natural movement.
Step 2: Fix Starter Clips
Secure starter clips in line with each joist to hold your first decking board. Make sure the gap between the wall and the first board is around 10mm.
Step 3: Install the First Deck Board
Tilt the first board slightly to fit the groove under the starter clip. Ensure it’s straight and seated properly before moving on.
Step 4: Add Hidden Fixing Clips
Slide decking clips into the groove of the first board.
Position a clip over each joist and fasten lightly, don’t overtighten yet. These clips automatically space boards by 5mm, ensuring even expansion gaps.
Step 5: Continue Laying Boards
Push the next board into the clips from the previous one. Repeat across the deck, inserting and tightening clips as you go. Use a move-stop clip near the centre joist of each board to limit expansion.
Step 6: End-to-End Joints
Where boards meet end-to-end, ensure each sits on its own joist and leave a 5–6mm gap for seasonal expansion. Sister joists are recommended where two boards meet.
Step 7: Finishing Edges
Once all boards are fitted, use starter or finishing clips to secure the final board.
Trim any overhang with a circular saw, then fit fascia boards or edge trims with stainless steel screws every 300–400mm (pre-drilling required).
Step 8: Posts & Railings (Optional)
If adding balustrades or steps, ensure all posts are anchored to the subframe, not directly through the decking surface.
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Composite Spindle Shoes for smart detailing under your handrails
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Composite Handrail Brackets in black or silver for a secure, seamless joinLeave small drainage holes in handrails to prevent water buildup.
Finishing Touches
A neat finish makes all the difference.
You can use:
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Fascia boards for clean edges
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End caps for hollow boards
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Colour-matched angle trims for a seamless look
Pre-drill all screw holes in composite material to prevent splitting and ensure a perfect finish.
Aftercare & Maintenance
Composite decking is designed for low maintenance, but regular cleaning helps it look its best:
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Wash occasionally with mild soap and water
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A light power wash (under 80 bars) removes dirt buildup
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Avoid solvent-based cleaners
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Rinse evenly to prevent water marks
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Wipe oil spills quickly to prevent stains
Water marks or slight fading are natural and will blend over time under UV exposure.
Download Installation Guides
Prefer to follow along with diagrams? You can download full PDF instructions below:
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