Facade Cladding Calculator — Boards, Wind Barrier & Fixings
Calculate cladding boards in linear metres, wind barrier area and screw quantities for back-ventilated facade systems. Supports timber, fibre cement and metal cladding on new-build and retrofit projects.
How the facade cladding calculator works
- 1Facade area = sum of all wall faces (m²), subtract windows and doors
- 2Board coverage: net area ÷ effective board width (visible width after overlap)
- 3Linear metres: board count × board length; order as running metre
- 4Wind barrier: facade area + 15% for laps and stapling waste
- 5Fixings: 1–2 fixings per stud line (follow manufacturer fastener specification); studs typically at 600 mm centres
- 6Battens (counter battens): facade area × lm per m² at batten spacing
Worked example
House facade: 80 m² net wall area. Horizontal boards 200 mm wide with 170 mm visible cover.
Board courses: 80 m² ÷ 0.17 m = 471 lm. Wind barrier: 80 × 1.15 = 92 m². Fixings: ≈ 780 screws at 1 fixing per stud line (600 mm spacing), or ≈ 1,570 screws at 2 fixings per stud line.
Frequently asked questions
What is a back-ventilated facade?
A cladding system with a continuous air gap (typically 25–50 mm) between the insulation/wind barrier and the cladding. The gap allows moisture to drain and evaporate, protecting the structure and dramatically extending cladding life.
What is wind barrier membrane and why do I need it?
Wind barrier (breather membrane) is a vapour-open, wind-tight layer installed over the insulation and behind the cladding. It prevents wind infiltration and protects insulation from moisture while allowing vapour to escape from inside the wall.
How much ventilation gap do I need behind cladding?
Minimum 25 mm for horizontal boards, 20 mm for vertical boards. Local standards may require more — Scandinavian and UK guidance typically specifies 25 mm ventilated plus 25 mm drained gap total (50 mm battens).
What screws should I use for timber facade cladding?
Stainless steel A4 (marine grade) screws are required for exterior cladding exposed to rain. A2 stainless is acceptable in sheltered locations. Never use standard zinc-plated or electro-galvanised screws — they corrode and stain the cladding.
How many fixings do I need per board?
Two fixings per board per stud is standard (one near each end of the board between studs). For boards wider than 150 mm, some specifications require three fixings to prevent cupping.