Project Inputs
White theme
Wall Geometry
0 for flat/parapet walls.
Windows/doors deducted from coverage.
Plank Options
Typical fiber‑cement plank length is 12 ft.
Visible height per course after lap.
Results
Net wall area
—
sq ft
Linear length required
—
ft
Approximate courses (rows)
—
Full‑length planks needed
—
Includes waste factor
Typical planks per row (rectangular portion)
—
Row Plan (Rectangular Portion)
Gable rows shorten progressively; adjust onsite. This plan assumes constant wall width.
| # | Row height (exposure) | Planks this row |
|---|
Example Data
| Wall width | Wall height | Gable height | Openings area | Plank length | Exposure | Starter | Waste | Result: Planks |
|---|---|---|---|---|---|---|---|---|
| 24 ft | 10 ft | 4 ft | 48 sq ft | 12 ft | 7 in | 0.75 in | 8% | ≈ 196 planks |
Common Plank Widths & Typical Exposures
| Nominal width | Typical exposure | Notes |
|---|---|---|
| 6.25 in | 5.0–5.5 in | Classic lap appearance |
| 7.25 in | 6.0–6.5 in | Balanced coverage & look |
| 8.25 in | 7.0 in | Very common residential choice |
| 12 in | 10–10.75 in | For wider profile aesthetics |
Formulas Used
We model two approaches:
- Lap Plank (Area/Exposure method):
Compute net area
A= rectangular area + gable triangle − openings − starter strip area.
Rectangular area =W × H. Gable triangle =0.5 × W × G.
Starter strip area =W × S(S = starter height).
Linear length neededLreq = A / E, whereEis exposure.
Full planks before waste =ceil(Lreq / Lplank).
Final planks =ceil( beforeWaste × (1 + waste%) ). - Sheet Panel (Tiling/Area method):
Net area
Aas above. Panel areaApanel = Wp × Hp.
Base panels =ceil( A / Apanel )(orientation affects seam layout, not area).
Final panels =ceil( base × (1 + waste%) ).
Notes: The row plan table assumes constant wall width; gable shortening is handled implicitly by the area method and will require onsite trimming.
How to Use This Calculator
- Select your unit system and calculation mode.
- Enter wall width, wall height, optional gable height, and total openings area.
- For planks: set plank length, exposure, starter height, and waste.
- For panels: set panel size, orientation, and waste.
- Click Calculate to compute counts, rows, and linear length.
- Review the row plan; adjust parameters for different elevations.
- Export CSV and PDF for estimating, purchase orders, or crew cut‑lists.
FAQs
It closely estimates total plank length by dividing net area by exposure. It inherently accounts for triangular gables and irregular widths through area, but seam layout and pattern preferences may change actual counts.
Use the visible height after lapping per manufacturer guidance. For 8.25‑inch planks, 7‑inch exposure is a common choice; smaller exposures increase rows and total linear length.
Yes. The starter consumes vertical height without adding exposed coverage. We subtract its area (width × starter height) before calculating required linear length.
Provide the sum of all window and door areas. The calculator deducts this from the wall area so you don’t over‑order boards.
Trim packages affect layout but typically have small impact on total plank length compared to exposure and openings. Consider adding a little extra waste if trims are unusually wide.
Yes. Switch to Sheet Panel mode and enter panel size. Orientation updates seam layout; counts use a tiling/area approach with your waste factor.
For straightforward walls, 5–10% often suffices. Complex elevations, tight staggering rules, or many openings can require 10–15% to cover offcuts and pattern constraints.