UK Decking Board Sizes & Profiles
Softwood and composite decking board sizes, profiles, lengths and fixing centres for UK garden decking projects.
Softwood Decking Boards
| Nominal Size (mm) | Finished Size (mm) | Lengths (m) | Profile |
|---|---|---|---|
| 32 x 100 | ~28 x 95 | 2.4, 3.0, 3.6, 4.8 | Grooved / smooth reversible |
| 32 x 125 | ~28 x 120 | 2.4, 3.0, 3.6, 4.8 | Grooved / smooth reversible |
| 32 x 150 | ~28 x 144 | 2.4, 3.0, 3.6, 4.8 | Grooved / smooth reversible |
| 38 x 150 | ~34 x 144 | 3.0, 3.6, 4.8 | Heavy-duty, commercial use |
Hardwood Decking Boards
| Species | Typical Size (mm) | Durability Class | Notes |
|---|---|---|---|
| Yellow Balau | 21 x 145 | Class 2 | Dense, naturally durable, smooth finish |
| Ipe | 21 x 145 | Class 1 | Extremely hard and durable, pre-drill required |
| Garapa | 21 x 145 | Class 2 | Light colour, good durability |
| European Oak | 27 x 150 | Class 2 | UK-sourced, use stainless steel fixings |
Composite Decking Profiles
| Type | Typical Size (mm) | Profile | Fixing |
|---|---|---|---|
| Solid composite | 20–25 x 140–150 | Grooved or smooth | Hidden clips or face screws |
| Hollow-core composite | 22–28 x 140–150 | Grooved edges | T-clips in grooves |
| Capped composite | 24 x 140 | Polymer-wrapped surface | Hidden clip system |
Decking Joist Sizes
| Joist Size (mm) | Max Span (mm) | Notes |
|---|---|---|
| 47 x 100 | ~1200 | Low-level decks only |
| 47 x 150 | ~2000 | Standard domestic decks |
| 47 x 200 | ~2800 | Larger spans, raised decks |
Related Calculators
Use the Decking Calculator for board and joist quantities, or the UK Timber Sizes reference for structural timber.
How We Calculate This
Frequently Asked Questions
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Last updated: April 2026
All calculations are estimates. Verify with your supplier.