04 Oct 2026
Planning a composite deck: boards, clips and trims explained
Composite decking is the shortest shopping list in the Garden & Outdoor range, and the easiest one to order incompletely — because the boards are only part of a deck. Decking holds five board finishes and one pack of clips, and the trim that finishes the exposed edge lives in a different section under a name that mentions wall panels. Here is what a deck needs, where each piece sits, and how to count it.
First, the honest limits. We sell materials, not labour: there is no fitting service, and there is no groundwork or sub-frame in the range. Joists, bearers, ground preparation, falls, spans and fixings into the structure are a tradesperson's call, and the manufacturer's instructions govern how the boards and clips go down. What this article can do is tell you what the parts are and how many packs an area takes.
The boards
All five decking boards are the 85 series, 290cm long, sold four pieces to a pack. The listings give each board as 15 × 290 × 2.3cm, with a pack covering 1.74m². The finishes are Decking 85A – Oak 03, 85B – Grey, 85D – Dark Brown, 85E – Black and 85F – Khaki. The descriptions call them composite with a wood grain texture and state that the boards are UV resistant; that is the product's own specification rather than a claim we are adding to it.
290cm is the number to plan around. If one dimension of the deck is at or just under 2.9m, boards can cross it in single lengths and the only cutting is at the ends. If it is longer, boards have to be joined, and where a join is allowed to fall is a sub-frame question rather than a shopping one.
What goes with them
| Part | Pack | What the listing states |
|---|---|---|
| Decking 85 board | 4 pieces | 15 × 290 × 2.3cm per board; 1.74m² covered per pack |
| Decking Fittings | 80 pieces | Slide into the decking groove and secure with a screw; screws not included |
| Wall Panel 73/83 Trim | 10 pieces | 4 × 4 × 290cm per trim; "can also be used with our decking" |
The clips
Decking Fittings (80pcs) is the fixing system. The description is plain about how it works: slide the fitting into the decking groove and secure it with a screw, no specialised tools needed. Eighty pieces to a pack — and this is the line to read twice — screws are not included. The listing does not state how many clips a board takes, so do not scale from a guess. That ratio belongs in the manufacturer's fitting instructions, which also govern spacing; the pack of 80 is the unit you order.
The trim, which is filed under wall panels
A finished deck has an exposed edge where the board ends and the frame would otherwise show. The part for that is Wall Panel 73/83 Trim – 290cm, over in Outdoor Trims & Fittings. The name is genuinely confusing, and the listing says so itself: "This can also be used with our decking." It is 4 × 4 × 290cm, ten pieces a pack, and every decking board listing names it as the compatible trim. If you search the site for a "decking trim" you will not find one under that name, because there isn't one — this is it.
A worked example: a deck 2.9m by 4m
Take a deck 2.9m across and 4m long — 11.6m² — with the boards running the 2.9m direction so that each board is a single uncut length.
- Boards by area: 11.6m² divided by 1.74m² a pack is 6.67, so seven packs.
- Boards by count, which is the figure to trust: 4m of length divided by the 0.15m board width is 26.7, so 27 boards. At four a pack that is seven packs, giving 28 boards and one spare.
- Clips: start with one pack of 80 and take the per-board figure from the fitting instructions. Buy screws separately.
- Edge trim: the perimeter is 13.8m. At 290cm a length that is five lengths, so a single pack of ten covers it with room for mitres and mistakes.
The two board calculations agreeing is a good sign. When they disagree, count boards rather than dividing area: a part-width board at the edge of a deck still costs a whole board, and an area sum quietly assumes you can use every offcut.
One more thing the arithmetic hides. A deck whose long dimension runs 4m means 27 board ends at each side, and both of those edges want trimming. Measure the perimeter you will actually see — a deck against a wall on two sides needs roughly half the trim of a free-standing one.
What the range does not include
Worth being blunt about, because it is most of a deck's real work:
- No joists, bearers, frames, posts or ground fixings. The range is boards, clips and trim.
- No screws. The clips listing states this plainly, and it is the commonest thing to be caught out by.
- No fitting, groundwork or site survey. We supply materials.
- No guidance from us on spans, falls, drainage or what a given base will carry. That is a tradesperson's judgement, read alongside the manufacturer's documentation.
Matching the deck to the fence and the walls
The five decking finishes — Oak 03, Grey, Dark Brown, Black and Khaki — use the same names as the 86 board series in Fencing and the 83 series in Outdoor Wall Panels. That means a deck, a boundary and a clad wall can be specified from one shade list, which is the main reason people buy across the three ranges at once. Compare the listing photographs before committing: shared names across three product series are a sensible starting point, and still worth confirming by eye, because two separate batches can read differently in the same light.
If you are matching a deck to cladding, note that the 73/83 trim does double duty — the same profile finishes the deck edge and the panel edge, so one part number covers both jobs.
A short ordering checklist
- Measure both dimensions and decide which way the boards run. Keep runs at or under 2.9m if you can.
- Count boards across the 0.15m board width, then round up to whole packs of four.
- Add clips, and add screws from somewhere else.
- Measure only the exposed perimeter for trim, in 290cm lengths.
- Have the sub-frame specified by someone qualified before any of it is delivered.
Everything here is bought in from a supplier and sold as materials. Delivery is free within 50 miles of our Glasgow store and £50 beyond. If a listing's compatibility note is not clear, the "Ask question about this product" button goes straight to us.