Roof underlay rolls.
Measure the selected roof planes and record the supplied strip direction.
Read the right quantitative data
Roll dimensions, selected side laps and end laps.
Check this ordering assumption
A roof-area figure without seam geometry cannot determine whole roll order.
Use a supplied membrane arrangement; no roof system is chosen.
A worked quantity method
This illustrative set of supplied inputs demonstrates Roof Membrane Roll Lap Calculator. Replace the example measurements and product figures with your own before ordering.
| Supplied input | Metric display | US display |
|---|---|---|
| Plane length along roll | 12 m | 39.37 ft |
| Plane width across courses | 3 m | 9.84 ft |
| Roll length | 10 m | 32.81 ft |
| Roll width | 1 m | 3.28 ft |
| Specified side lap | 100 mm | 3.94 in |
| Specified end lap | 200 mm | 7.87 in |
Membrane rolls without cross-course offcut reuse: 8 rolls
- Courses
- 4
- Rolls per course
- 2
Your measurement and product-data sheet
Record what you know and mark verified items ready. Notes save on this browser after you edit them. Download a copy before clearing browser data.
Measure the selected roof planes and record the supplied strip direction.
Roll dimensions, selected side laps and end laps.
A roof-area figure without seam geometry cannot determine whole roll order.
Input for Roof Membrane Roll Lap Calculator. Record the value with its unit and quantity basis.
Input for Roof Membrane Roll Lap Calculator. Record the value with its unit and quantity basis.
Input for Roof Membrane Roll Lap Calculator. Record the value with its unit and quantity basis.
Input for Roof Membrane Roll Lap Calculator. Record the value with its unit and quantity basis.
Input for Roof Membrane Roll Lap Calculator. Record the value with its unit and quantity basis.
Input for Roof Membrane Roll Lap Calculator. Record the value with its unit and quantity basis.
Choose your next calculation
Roof Membrane Roll Lap Calculator
Count membrane courses and rolls for supplied roof-plane dimensions and specified side and end laps.
Roof Plane Area Calculator
Sum the geometric area of specified roof planes from horizontal run, rise and ridge length.
Turn the estimate into an order
- Confirm that all quantities use the same measured basis and the selected product's current data.
- Keep different products, finishes and handed variants in separate purchase lines.
- Review exact demand and whole-pack purchase quantities before entering your quoted prices.
- Record compatible stock already on hand, then save the remaining order in your browser project.
Measurement and purchase guides
Other materials in this family
Reviewed 6 October 2026. Geometry and purchase arithmetic use your measurements and selected specifications. Calculation scope.