How Many Tongue and Groove Boards Do I Need?
Quick Answer
You need approximately 20 boards for a 3m × 2.4m wall
Based on: standard 119mm coverage width T&G boards fitted horizontally across a 2.4m high wall
How We Calculated This
Tongue and groove boards overlap, so the coverage width is less than the overall board width. The calculation is:
- Wall height: 2.4m (2,400mm)
- Board coverage width: 119mm (from a 125mm nominal board)
- Boards needed: 2,400 ÷ 119 = 20.2, round up to 20 boards
- Board length: 3m to match the wall width (or longer, to be trimmed)
Common T&G Board Sizes
- Standard softwood: 125mm × 16mm (119mm coverage)
- Shiplap profile: 125mm × 19mm (112mm coverage)
- Wide board: 150mm × 16mm (144mm coverage)
- Matchboard: 100mm × 12mm (94mm coverage)
Lengths are typically available in 1.8m, 2.4m, 3.0m, 3.6m, and 4.8m.
Horizontal vs Vertical Fitting
The number of boards depends on the orientation:
- Horizontal: divide the wall height by the coverage width
- Vertical: divide the wall width by the coverage width
For a 3m × 2.4m wall fitted vertically, you would need: 3,000 ÷ 119 = 26 boards at 2.4m length.
Wastage Allowance
Allow 5–10% extra for cuts, defects, and end-matching. For 20 boards, order 22 to be safe. If you have openings (doors, windows), subtract their area but keep the wastage allowance — short offcuts are rarely reusable.
Fixing Materials
You will also need:
- Battens: 25mm × 50mm treated softwood at 400–600mm centres
- Panel pins or secret nails: 30–40mm, approximately 6 per board
- Adhesive (optional): grab adhesive for additional hold
- Skirting/beading: to finish edges at floor, ceiling, and corners
Typical UK Costs
- Standard softwood T&G (3m): £3–£5 per board
- MDF T&G panels: £8–£15 per panel
- Oak T&G: £12–£25 per board
- Pine V-groove T&G (pack of 5): £15–£25
Last updated: April 2026