Wood Cladding Calculator — boards, battens and cost estimate

Tongue and Groove (T&G)

Interlocking profiled boards with a tongue on one edge and a groove on the other. The most popular internal and external cladding in the UK. Boards slot together tightly, producing a neat, uniform finish. Vent channels on the back side allow moisture to escape. Common thicknesses range from 8 mm to 19 mm with working widths of 86 mm to 112 mm. Available in Scandinavian pine, spruce, larch and cedar.

Shiplap

Overlapping profile where each board sits over the one below, shedding rainwater naturally. Widely used for garden buildings, sheds, fencing and external wall cladding across the UK. The overlap typically gives a shadow line and a traditional appearance. Thicknesses from 12 mm to 16 mm, working widths 109 mm to 137 mm. Commonly supplied in treated Scandinavian pine or Western Red Cedar.

Featheredge (Cladding Board)

Tapered boards, thicker at one edge than the other, nailed overlapping to form a traditional weatherboard finish. One of the oldest forms of external cladding in Britain, often seen on barns, agricultural buildings and period properties. Each board overlaps the one below by approximately 25 mm. Available in softwood (treated pine) or hardwood (oak, larch).

Wood Species

Scandinavian Pine — the most widely used softwood in UK construction, imported from Sweden and Finland. Pressure-treated for external use. Western Red Cedar — naturally durable, lightweight, sourced from Canada. Ideal for premium external cladding without treatment. European Larch — strong, resinous, grows in the UK and Alps. Good natural durability for external use. Douglas Fir — structural-grade softwood, imported from North America. Siberian Larch — very dense, highly durable, slow-grown. European Oak — traditional British hardwood for high-end cladding and structural work. Whitewood (Spruce) — lightweight, affordable softwood sold by Jewson and other trade merchants, often used for general-purpose cladding and internal lining.

Grades

A Grade — clear, no visible defects. AB Grade — minimal small tight knots. B Grade — some knots and minor colour variation. C Grade — knots, minor splits, economy grade. Unsorted — mixed grade, often the most economical option for utility buildings.

Breather Membrane

For external cladding, a breather membrane (e.g., Tyvek or similar) is required behind the battens to protect the wall from moisture while allowing vapour to escape. Calculate membrane area as your total wall area plus 10% for overlaps. Standard rolls are 1.5m × 50m (75 m²).