Imperial (ft/in)
Switch units or apply presets anytime.
ft²
You can enter already sloped area from drawings or takeoff.
in
ft
in
in
%
$
Auto-fills when changing Brand or Price tier.
ft
If zero, model falls back to simple single end-lap.
%
Adds an additional layer over this fraction of base area.
ft
ft
ft
ft
Model: For a course of length R, N rolls cover N·L − (N−1)·E ≥ R. Average exposure/roll = L − ((N−1)/N)·E. Double-coverage adds area for the extra layers.
Results
0
Rolls required
0
Eff. coverage per roll
0
Leftover after rounding
0
Required area incl. waste
0
Exposure width × length
0
Material cost
Exposure width = Roll width − Side lap
Exposure length uses joint model when enabled
Example Roll Specs
Illustrative values only. Adjust overlaps to match manufacturer guidance and local codes.
| Product | Roll width | Roll length | Side lap | End lap | Eff. coverage | Notes |
|---|
Formula used
- Slope factor = √(1 + (rise/run)2).
- Section sloped area = (area or L×W) × slope factor when needed.
- Base area = sum of sloped areas (or single input if batch off).
- Double coverage area = base×(pct/100) + eavesLen×eavesBand + valleyLen×valleyWidth.
- Design area = base area + double-coverage additions.
- Required area = design area × (1 + waste%).
- Exposure width = roll width − side lap overlap.
- Exposure length: simple = L − E; joint model = L − ((N−1)/N)·E.
- Coverage/roll = exposure width × exposure length.
- Rolls = ceil(required area ÷ coverage/roll).
For complex roofs or prescriptive zones, increase waste or split into additional sections.
How to use
- Select units and input mode, or enable batch sections.
- Enter areas or dimensions with slope per section.
- Pick a brand, code preset, and price tier.
- Enable joint modeling or double-coverage zones if applicable.
- Review KPIs for coverage, rolls, and cost.
- Export CSV or PDF for records and purchasing.
FAQs
Each row can be Area or Dimensions. Sloped area is computed per row and summed for the base design.
Yes. Turn on double-coverage and use percentage or linear lengths × strip widths to add extra layers.
Selecting a tier auto-fills price per roll for the chosen brand. You can override the value any time.
Yes. Waste covers cuts, starts, ends, and detailing. Presets may increase the minimum waste automatically for certain conditions.
Unit labels update immediately. Values are not auto-converted; re-enter in the proper system when switching.
No. It’s optional for long runs or multiple roll seams. For short runs, the simple end-lap is usually sufficient.