Inputs
Results
Enter your deck dimensions then click Calculate.
UKUK Building Regulations
References & Sources
Standards Cited
- TRADA Technology — Timber Decking — Design and Construction Guide
Provides guidance on joist spacing, board thickness, gap sizes, and structural requirements for timber decking - BS 8417 — Preservation of wood — Code of practice
Guidance on timber treatment and preservation for external decking exposed to weather
Formulas Used
- Deck Area:
A = deckWidth x deckLength
Source: Standard geometry - Boards Across Width:
boards = ceil(deckWidth_mm / (boardWidth + gapSize))
Source: TRADA Technology decking guidance — Effective board width includes the gap between boards - Joists Required:
joists = ceil(deckLength_mm / joistSpacing) + 1
Source: TRADA Technology decking guidance — First joist at 0mm, then at each spacing interval - Screws Needed:
screws = boardsNeeded x joistsRequired x 2
Source: TRADA Technology decking guidance — 2 screws per board per joist intersection - Linear Metres of Board:
linearMetres = boardsNeeded x deckLength
Source: Standard calculation
Key Assumptions
- Recommended joist spacing: 300mm for boards <20mm thick, 400mm for <25mm, 450mm for <32mm, 600mm for >=32mm — TRADA Technology decking guidance
- Gap between decking boards typically 3-6mm for drainage and expansion — TRADA Technology decking guidance
- 10% wastage allowance for cuts at board ends — Industry standard practice
- 2 screws per board at each joist crossing point — TRADA Technology decking guidance