Cladding Coverage CalculatorTimber Cladding Coverage Calculator
Estimate the linear metres and number of cladding boards for any wall, working in effective cover width for shiplap, tongue-and-groove, featheredge and board-and-batten profiles. Deducts openings and adds waste.
Why this calculation matters
Coverage decides the order quantity, and coverage is the covering width, not the board width. Ignoring the lap under-orders every job.
Cladding Coverage Calculator
Timber Cladding Coverage Calculator
Total door + window area.
Exposed width after overlap. Auto-set by profile.
This picker does not change the answer. Coverage depends only on the dimensions you enter, not on the species — that is what makes it a rule rather than an estimate. The species is here so you can note it on a printout.
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About Cladding Coverage Calculator
Timber cladding boards overlap or interlock, so the width they actually cover on the wall (the effective cover) is less than the board's full width. This calculator works in effective cover to give an accurate count of linear metres and boards for any wall, after deducting openings and adding a waste allowance - so you order the right amount of shiplap, tongue-and-groove or featheredge. It tells you how many cladding boards a wall needs and the effective cladding coverage per m2 once profile overlap is deducted.
Where Is This Used?
Class temperature is species-specific. The ITWA handbook sets the Thermo-D temperature per species, not once for the class: Pine and Spruce 212 ±3 °C, Radiata Pine 230 ±3 °C, Hemlock 225 ±3 °C, Ayous 208 ±3 °C, Iroko 190 ±3 °C, Ash and Frake 212 °C (−2/+5). Thermo-S is 190 ±3 °C for all species. Enter the temperature your supplier actually used — a class name alone does not fix it.
Formulas Used
Net area = (Wall width x height) - OpeningsLinear m per m2 = 1000 / Effective cover width (mm)Total linear = Net area x Linear per m2 x (1 + waste%)Boards = ceil(Total linear / Board length)Courses = ceil(Wall height / Effective cover)How the calculation works
Coverage is driven by the covering width, not the board width — the lap is overlapped material and is not usable area. Ordering on board width is the single most common way a cladding order comes up short.
Show the formula
Net area = wall area - openings. Linear metres per square metre = 1000 / covering width in mm. Total linear = net area x that x (1 + waste). Boards = ceiling(total linear / board length).Rectangular walls. Corner details, mitre waste and battens are not modelled, and profile tolerance differs between mill runs.
References and what each one provides
- EN 350CENDurability classification of wood and wood-based materials. Classes 1–5 describe heartwood resistance to fungal decay.
Unverified values are marked as such rather than presented as sourced.
Limitations of this calculation
Counts boards from covering width and area. It does not account for openings, corner details, mitre waste, batten and fixing requirements, or profile tolerance differences between mill runs.
Do not use this for Firm ordering without a site measure and a check of profile coverage with the supplier.
Figures are engineering estimates from the inputs and assumptions shown. Verify against the actual material and, where the result affects structure or safety, against a qualified professional.
- Effective-cover geometry; rows = ceil(height ÷ cover)
Formula checked against the sources above by an automated regression test (tests/verify-phase2.js) that derives each expected value independently of this page. Last reviewed .
How to use this tool
- Enter your project details below, then press Calculate.
- Pick your profile from the dropdown.
- Fill in wall width, wall height, openings to deduct, effective cover width.
- Press Calculate.
Worked example
Common mistakes to avoid
- Ordering by wall area without the profile's cover width. A 140 mm board may cover only 125 mm.
- Forgetting openings are not free. Windows and doors still generate cutting waste around them.
- Ignoring the fixing battens in the material list. Cladding needs its substructure too.
Frequently Asked Questions
Wood species data
Density, hardness and movement for 60 timbers