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Timber Cladding Calculator

Calculate boards, linear metres, and battens for board on board, shadow gap, open joint, and horizontal lap cladding. Supports multiple walls with opening deductions.

Timber Cladding Calculator

Board on board, shadow gap, open joint, and lap profiles - with full batten system quantities

Two layers of boards - front boards cover the gaps between back boards. The standard contemporary UK timber cladding detail.
Durable Class 3 · Natural oil finish recommended · Allow to weather to silver-grey or treat annually to retain colour.
Face width of each board
Standard: 3.0, 3.6, 4.2, 4.8, 6.0 m
How much the front board covers the back board on each side - typically 30-50 mm
Visible gap between boards - typically 15-30 mm for shadow gap, 20-50 mm for open joint
Overlap between courses - typically 25-40 mm
- enter board dimensions
Counter battens fix to the wall studs; cladding battens run perpendicular and carry the boards.
Fix to studs - typically 400 or 600 mm centres
Perpendicular to boards - typically 300-600 mm
10%
10% standard; 15% for complex shapes or many penetrations

Wall Sections

Job Costing (optional)

~8-12 m² per litre depending on porosity

Results

Cladding Boards

Net Cladding Area
-
m² (less openings)
Boards to Order
-
inc. waste
Linear Metres
-
boards total

Batten System

Counter Battens
-
lengths
Cladding Battens
-
lengths
Total Batten LM
-
linear metres

Wall Breakdown

Wall Gross Area Openings Net Area Boards Counter Battens (lm) Cladding Battens (lm)

Profile Guide

  • Board on board - Vertical boards fixed to cladding battens, with a second layer of front boards covering the gaps. Very popular contemporary detail. Two boards per "slot".
  • Shadow gap - Vertical boards fixed with a precise gap between them. The gap creates a shadow line for a clean, modern look. A breather membrane behind is essential.
  • Open joint rainscreen - Similar to shadow gap but with wider gaps (20-50 mm), used on ventilated rainscreen systems. The wall behind must be weatherproof independently.
  • T&G vertical - Tongue and groove boards fixed vertically. Secret-fixed through the tongue for a clean face. Very tight, weathertight profile.
  • Larch / Cedar lap - Horizontal lapped boarding, similar to featheredge but in premium timber species. More traditional look than vertical profiles.

Species & Durability

  • Larch - Durable Class 3-4. Good value, weathers to silver-grey. The most commonly specified UK cladding timber.
  • Western Red Cedar - Class 3-4. Lightweight, stable, aromatic. Naturally resistant to decay; treat to retain colour.
  • Oak - Class 2. Extremely durable but heavy. Tannin staining from fixings - use stainless steel only.
  • Douglas Fir - Class 3. Strong and stable. Good alternative to larch at lower cost.
  • Accoya - Modified pine, Class 1 durability. 50-year guarantee above ground. Very stable, minimal movement.
  • Thermowood - Heat-treated pine or ash. Class 2-3. Dark colour, reduced movement, eco credentials.
  • Treated Pine - Pressure-treated softwood. Class 3-4 with treatment. Most economical option.

Batten System

  • Counter battens - Fixed horizontally to the wall structure through a breather membrane, creating a ventilation cavity behind the boards.
  • Cladding battens - Run perpendicular (vertically for horizontal boards; horizontally for vertical boards) to carry the cladding.
  • Minimum 25 mm ventilated cavity behind all external timber cladding
  • Use stainless steel or hot-dip galvanised fixings throughout - never standard zinc
  • Allow 10-15 mm gap at ground level for drainage and airflow

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