MEASURE ONCE. PLAN YOUR PURCHASE.

Roof Sheet Side and End Lap Order calculator.

Count whole rectangular roof sheets on supplied measured planes with specified side and end laps. No pitch, fixing pattern, roof structure or weather performance is selected.

ROOFING

Your inputs

Metres, litres

Use measurements from your plan and properties from your chosen product. Any prefilled values are illustrative.

Sheet width

Where to get this value

Measure this dimension in your plan or on site and use the displayed unit. For irregular shapes, divide the geometry into the supported sections.

Sheet length along slope

Where to get this value

Measure this dimension in your plan or on site and use the displayed unit. For irregular shapes, divide the geometry into the supported sections.

Specified side lap

Specified end lap

Your additional whole spare sheets

Independent rectangular roof plane 1

Measured width across sheets

Where to get this value

Measure this dimension in your plan or on site and use the displayed unit. For irregular shapes, divide the geometry into the supported sections.

Measured slope length

Where to get this value

Measure this dimension in your plan or on site and use the displayed unit. For irregular shapes, divide the geometry into the supported sections.

Identical components

YOUR ESTIMATE

A clear estimate starts here.

Enter your dimensions and product details to see the quantity and purchase breakdown.

CONTINUE YOUR PLAN

Find the next material.

Keep the quantity, then use another tool for the remaining parts of your purchase.

Explore all calculators

Formula and assumptions

BEHIND THE NUMBERS

How this calculation works.

Count whole rectangular roof sheets on supplied measured planes with specified side and end laps. No pitch, fixing pattern, roof structure or weather performance is selected. Across = max(1, ceil((plane width − side lap)/(sheet width − side lap))); down = max(1, ceil((plane slope length − end lap)/(sheet length − end lap))); sheets = Σ(across × down × count) + supplied spare sheets.

Across = max(1, ceil((plane width − side lap)/(sheet width − side lap))); down = max(1, ceil((plane slope length − end lap)/(sheet length − end lap))); sheets = Σ(across × down × count) + supplied spare sheets.Calculated with normalised units

A worked example

Illustrative inputs only. Product properties and design dimensions are not recommendations for your project.

Sheet width: 1 m
Sheet length along slope: 2 m
Specified side lap: 100 mm
Specified end lap: 200 mm
Your additional whole spare sheets: 1
Measured width across sheets: 2.8 m
Measured slope length: 3.8 m
Identical components: 1

Whole roof sheets: 7 sheets

Full sheets, fixed orientation and no offcut reuse between planes. Enter slope length, not horizontal run. Effective rib coverage and permitted laps must be supplied.

Before you purchase

Use dimensions from your plan and properties from your chosen product. Any design spacing, section or fixing pattern must already be specified.

Counts quantities from an existing supplied specification. Does not design construction, certify safety, recommend application requirements or establish code compliance.

Example dimensions and product properties are illustrative arithmetic inputs only. Obtain actual yield, density and coverage from your selected supplier.

Method: dimensional arithmetic and user-supplied specifications. Software checks: 2026-10-08. Calculation and review policy.