Weatherboard Calculator

Enter board type, dimensions, and overlap - effective cover is calculated automatically

Board Type

Tapered board nailed at the bottom - overlap the thicker edge of the board above. Most common UK external timber cladding.

Board Width (mm) Full face width of the board

Overlap (mm) 0 for shiplap, T&G, and square edge

Board Length (m) Standard: 3.6 m, 4.2 m, 4.8 m, 6.0 m

Effective Cover per Board

- enter width and overlap

Stud / Batten Spacing (mm) Fixings per board = wall width ÷ stud spacing

Fixings per Stud 1 per stud for featheredge; 2 for T&G face-fixed

Waste Factor (%)

10%

10% for straightforward runs; 15% for complex shapes, many cuts, or diagonal boarding

Cost per board

Cost per fixing (nail/screw)

Primer / treatment per litre ~10 m² per litre for end-grain primer

Labour per m²

Delivery (flat fee)

Net Cladding Area
-
m² (less openings)

Boards to Order

inc. waste

Linear Metres

boards ordered

Fixings

nails / screws

Wall	Gross Area	Openings	Net Area	Boards	Fixings

Featheredge - Tapered board, thicker at the bottom, overlapped. The most traditional UK external cladding. Fixed with one nail per stud through the bottom only - do not nail through the overlap.
Shiplap - Rebated profile that interlocks; no exposed overlap. Very clean, contemporary look. Fix through the rebate.
Tongue & Groove - Boards slot together; can be laid horizontally or vertically. Secret-fixed through the tongue for a clean face, or face-fixed with two nails.
Square edge - Plain boards fixed with a visible gap or butted. Simple, rustic finish. Requires two fixings per board per stud.
Composite / fibre cement - Hardie Plank and similar. Pre-primed, very durable. Fixed as per manufacturer's spec - typically secret fixed or face nailed.

Featheredge - 100, 125, 150, 175, 200 mm
Shiplap - 100, 125, 150 mm (face width)
T&G - 95, 120, 145 mm (cover)
Composite - 150, 180, 230 mm (coverage)
Always use the cover / face width, not the overall board width, to calculate effective coverage.

Use stainless steel or hot-dipped galvanised nails - standard zinc nails corrode and stain timber
Ring-shank nails give better holding power than smooth-shank
Pre-treat all cut ends with end-grain preservative before fixing
Leave 1-2 mm gap between boards for expansion (featheredge)
Stud / batten spacing: 400-600 mm centres - closer spacing for longer boards
Primer coat before and after installation gives the best finish life