Free cladding calculator. Linear metres, sheets, and fixings for weatherboard and sheet cladding.
This calculator counts the rows, lineal metres and fixings for weatherboard and sheet cladding on a wall. The number that matters most on this page is cover width, and there is a reason it comes from where it does.
A weatherboard covers less than its nominal size, because it laps the board below it. This page takes cover from CostMate's own per-profile cover table — the same data a paid estimate uses — rather than from the size printed on the board.
It did not always. The options here used to be four hand-written entries that treated the nominal size as the cover: a 150 by 25 pine bevel-back counted as covering 150mm. The engine already knew it covers 125mm. On a 12m by 2.7m wall that is 15 rows against a true 18 — a 20% under-order, on the free tool a builder is most likely to reach for first.
There is a lesson in the intermediate fix, too. Relabelling those entries to say cover made the label honest about what the number meant without making the number right. Reading a page's own labels is not a substitute for checking the data behind them.
Driving the options off the engine's table means this calculator and a paid estimate cannot drift apart, and a profile added to the engine appears here without anyone touching this page.
Four materials are offered — pine bevel-back, cedar vertical, cedar horizontal, and fibre cement — each with its own profiles and cover widths.
Openings are deducted by count and area, and a 10% wastage allowance is applied to the lineal metres.
Fixings come from the stud centres and the nails per board-to-stud crossing you set. Both are inputs, because fixing patterns vary with profile, with exposure, and with whether the cladding is direct-fixed or on a cavity.
Cavity construction, flashings and weathertightness detailing are design decisions. Check them against your plans, NZ Building Code E2 and the cladding manufacturer's system, and confirm cover widths with your supplier, before you order or fix.