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What lengths do decking boards come in?
Timber and composite are sold in different lengths. Wickes’ timber boards come in 1.8, 2.4, 3.6 and 4.8 m. The composite boards we have verified are:
| Length | Boards we have checked |
|---|---|
| 3.6 m | Millboard Lasta-Grip, Millboard Enhanced Grain, Millboard Weathered Oak |
| 3.65 m | Trex Transcend, Trex Transcend Lineage, Trex Enhance |
| 4 m | Envirobuild Explorer, Cladco Signature Solid, Cladco ProDeck, Cladco Signature, Envirobuild Frontier |
| 4.8 m | Eva-Last Apex, Eva-Last Infinity I-Series |
| 4.87 m | Trex Transcend, Trex Transcend Lineage, Trex Enhance |
Ecoscape’s composite boards are sold as 3 m boards at £18 to £33.25 plus VAT, in an article without a date. The 2.4 m board is a timber length: Wickes’ standard board is 25 by 120 mm at £8. That makes 2.4, 3, 3.6, 4 and 4.8 m the lengths you’ll actually search for.
How wide and thick are they?
Widths run from 134 mm (Eva-Last Infinity) to 200 mm (Millboard Weathered Oak and Lasta-Grip) among composite boards. Thickness is 21 to 32 mm: Envirobuild’s Explorer is 21 mm, Millboard’s boards are 32 mm. Wickes’ timber boards are 25 mm or 27 mm thick and 120 or 144 mm wide. Thickness affects stiffness and the joist centres a maker allows, so don’t swap boards on an existing frame without checking.
Which length wastes least?
The one that equals your run, or divides into it with the smallest offcut. The table at the end of this page shows boards per row and the share of each board you cut off.
How heavy are the boards?
EnviroBuild gives hollow 150 mm boards at 2.5 to 3.5 kg per metre and solid at 4.5 to 6. A 4 m solid board therefore weighs roughly 18 to 24 kg, which is awkward to carry alone, and a 4.8 m board is longer still.
How do I turn lengths into a shopping list?
Enter your deck and board size in the board calculator. EnviroBuild suggests allowing 5 to 10 percent for cuts and 15 percent or more for diagonal or herringbone layouts. Millboard says a cut board needs at least three joists under it, so very short pieces are a problem. See the boards comparison for sizes of each product.
Offcut waste by deck run and board length
Each cell shows the boards one row needs and the share of the bought length cut off, if offcuts are not reused. Green cells waste 5% or less.
| Deck run | 2.4 m boards | 3 m boards | 3.6 m boards | 4 m boards | 4.8 m boards | 5.4 m boards |
|---|---|---|---|---|---|---|
| 2.4 m | 1 · 0% | 1 · 20% | 1 · 33.3% | 1 · 40% | 1 · 50% | 1 · 55.6% |
| 3 m | 2 · 37.5% | 1 · 0% | 1 · 16.7% | 1 · 25% | 1 · 37.5% | 1 · 44.4% |
| 3.6 m | 2 · 25% | 2 · 40% | 1 · 0% | 1 · 10% | 1 · 25% | 1 · 33.3% |
| 4 m | 2 · 16.7% | 2 · 33.3% | 2 · 44.4% | 1 · 0% | 1 · 16.7% | 1 · 25.9% |
| 4.2 m | 2 · 12.5% | 2 · 30% | 2 · 41.7% | 2 · 47.5% | 1 · 12.5% | 1 · 22.2% |
| 4.8 m | 2 · 0% | 2 · 20% | 2 · 33.3% | 2 · 40% | 1 · 0% | 1 · 11.1% |
| 5 m | 3 · 30.6% | 2 · 16.7% | 2 · 30.6% | 2 · 37.5% | 2 · 47.9% | 1 · 7.4% |
| 6 m | 3 · 16.7% | 2 · 0% | 2 · 16.7% | 2 · 25% | 2 · 37.5% | 2 · 44.4% |
Lengths with verified products in our UK list: 3.6 m, 3.7 m, 4 m, 4.8 m, 4.9 m. Other lengths are shown for comparison only.
Questions
What size are decking boards?
Timber boards at Wickes are 25 by 120 mm and 27 by 144 mm. Composite boards we have checked are 134 to 200 mm wide, 21 to 32 mm thick and 3.6 to 4.87 m long.
Do 3 m decking boards exist?
Ecoscape quotes composite boards by the 3 m board. None of the composite boards we verified is 3 m, and Wickes sells timber in 1.8, 2.4, 3.6 and 4.8 m, so check the exact length the seller gives.
Is there a 5 m decking board?
None of the UK boards we checked is 5 m; the longest is 4.87 m. If a seller lists 5 m boards, check the exact length against your deck run.
Is a longer board always better?
No. Longer boards mean fewer butt joints, but if the length doesn't divide your run you pay for offcut. A 4.8 m board on a 4 m run throws away about 17 percent of each board.
Sources
- Timber Decking Boards - Wickes
- Hollow Vs Solid Composite Decking - Ecoscape
- Composite Decking Board Guide - EnviroBuild
- Millboard Installation and User Guide (hosted by Cladco)
- Eva-Last Apex (manufacturer)
- Eva-Last Infinity I-Series (manufacturer)
- Trex Transcend (manufacturer)
- Trex Transcend Lineage (manufacturer)
- Trex Enhance (manufacturer)
- Envirobuild Explorer (manufacturer)
- Cladco Signature Solid (manufacturer)
- Millboard Lasta-Grip (manufacturer)
- Millboard Enhanced Grain (manufacturer)
- Millboard Weathered Oak (manufacturer)
- Cladco ProDeck (manufacturer)
- Cladco Signature (manufacturer)
- Envirobuild Frontier (manufacturer)