Does the roof calculator provide a quotation?

No. It produces approximate planning quantities for simple roof geometry. A quotation requires an assessment of the roof, access, junctions and existing construction.

Why is a waste allowance included?

Cutting, breakage, laps and roof details can increase material needs. The correct allowance depends on the product and roof layout.

Can I use the result to order materials?

Use it as an early planning guide only. Confirm product coverage, laps, gauge, roof measurements and quantities with the installer or supplier before ordering.

Useful planning tools

Roof project planner

Estimate the surface area of a simple pitched roof, explore approximate material quantities and prepare a clearer loft-conversion brief.

Calculation used Roof surface ≈ footprint ÷ cos(pitch)

The result is an early guide. Complex roofs, valleys, dormers, abutments, product specifications and site access require a proper assessment.

Roof area and materials

Pitched-roof calculator

Enter plan measurements for the building beneath the roof. Use the manufacturer’s stated coverage for the exact tile or slate being considered.

Approximate finished roof surface area
Indicative tile or slate unit quantity
Indicative membrane roll count
Approximate linear metres of battens

Building length in metres

Building width in metres

Uniform roof pitch

Planning allowance

Tiles or slates per m²Check the exact product datasheet.

Membrane coverage per roll, m²Use effective coverage after specified laps.

Batten gauge in millimetresGauge must be confirmed for the selected roof covering and pitch.

Roof surface—approximate m²

Tiles or slates—units including allowance

Membrane—whole rolls

Battens—approximate linear metres

Planning guide only. Do not order materials or price work from this result without verified roof measurements, product specifications and a site assessment.

Before construction

What a loft enquiry should cover

Existing roof

Roof form, covering condition, head height and visible structural arrangement.

Design and approvals

Planning position, structural design, building regulations, fire safety and any party-wall requirements.

External weathering

Dormer covering, roof windows, insulation, ventilation, flashings, gutters and junctions with the existing roof.

Next step

Turning an estimate into a real quote

Send the approximate measurements, property location and a few clear photographs. We can then discuss access, roof details and whether an assessment is suitable.

Request a roofing quote