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Roofing calculator: how many roof tiles and battens do I need?
Estimate tiles, battens, membrane, ridge and fixings for a pitched roof. Enter the roof area, choose the tile type and add the eaves, verge and ridge lengths.
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How the calculation works
The number of tiles per square metre depends on the tile size and the headlap (how much each row overlaps the one below). Large interlocking tiles need around 10 per square metre; small plain tiles need many more.
Battens are worked out from the roof area and the batten gauge, and membrane from the roof area plus overlaps. Ridge, verge and eaves items are counted from the lengths you enter.
Things to check
Follow the tile manufacturer's minimum pitch and headlap for your roof, and use graded, treated battens.
Measure the roof slope, not its footprint on plan: a pitched roof has a larger area than the floor below it.
Worked example
A 50 m² roof in interlocking tiles with 10 m of eaves and 10 m of ridge:
| Material | Quantity | Price (ex VAT) |
|---|---|---|
| Easy Trim Grafter Breather Membrane 50m X 1m | 1 | £78.37 |
| Graded BS5534 Treated Roofing Batten 25mm x 50mm x4.8m | 31 | £191.58 |
| Easy Trim 3 In 1 Ventilation Accessory Pack | 2 | £86.46 |
| Easy Trim Easyridge Plus Dryfix Ridgekit Black 6m | 2 | £112.68 |
| Paslode Galvanised-Plus IM350 Collated Nails 2.8mm x 63mm 1100 Pack | 1 | £35.83 |
| Marcrist CK650SF Multi-Material Diamond Blade 115mm x 22.2mm | 1 | £46.90 |
| Materials total | £551.82 | |
Today's prices, excluding VAT and delivery. Labour, plant hire and some items are priced when you request a quote. Use the calculator above for your own measurements.
Frequently asked questions
How many roof tiles per square metre?
About 10 for large interlocking tiles, and far more for plain tiles. It depends on the tile size and headlap.
How do I measure a roof area?
Measure along the slope from eaves to ridge, multiply by the length of the roof, and repeat for each slope.
Do I need a breather membrane?
Most modern pitched roofs use a breathable underlay beneath the battens to keep out wind-driven rain while letting moisture escape.