Ensure you have the correct amount of slate tiles for your roof.
Our online calculator lets you work out exactly how many your roof will require, along with other useful calculation such as batten gauge, number or battens and a tile holing gauge.
Calculate Number of Slates
How to Use
- Tile Size: the dimensions of your slate tile.
- Headlap: the desired headlap (overlap between tiles) in millimetres.
- Roof Area (Optional): the total area of your roof in square metres.
- Calculate: Click the 'Calculate' button to get the number of tiles per square metre, the batten gauge, the holing gauge, and, if roof area is provided, the total tiles and battens needed for the roof.
Calculator checked on By Jamie
Calculations Used
| Batten Gauge | (Length of Slate - Headlap) / 2 |
| Holing Gauge | Batten Gauge + Headlap + 10mm |
| Tiles Needed per Square Metre | Depends on tile size and headlap |
| Total Tiles Needed | Tiles per Square Metre × Roof Area |
| Total Battens Needed | Battens per Square Metre × Roof Area |
Half Slates at the Verge
In order to maintain the necessary half bond it is standard practice to alternate between full and 'slate and half' size slates at the verge. These tiles are 150% the width of a standard slate tile.
Consider a slate measuring 600 x 300. This would require one and a half slates of the size 600 x 450 for each linear metre so you would need 3 of these larger slates per linear metre.
Frequently Asked Questions
What is the Headlap?
This refers to the overlap that occurs between the top edge of a slate tile and the slate two layers below it. This overlap is crucial for ensuring the roof is waterproof and durable.
What is a Batten Gauge?
The batten gauge is the distance between the battens where slates are fixed on the roof.
How is the Holing Gauge different from the Batten Gauge?
The holing gauge is the distance from the tail of one slate to the nail hole of the slate above it which includes the batten gauge, the headlap, and an additional 10mm.
Why do I need to know the Headlap?
The headlap is necessary for calculating the batten gauge and holing gauge, ensuring the slate tiles overlap correctly to provide waterproofing and durability.
What does 'Tiles Needed per Square Metre' mean?
It indicates the number of slate tiles required to cover one square metre of roofing area considering the selected tile size and headlap.
What is the significance of the 'Total Battens Needed' calculation?
This calculation helps you estimate the total length of battens required to install the slates for the entire roof area.
How accurate is the Slate Roofing Calculator?
The calculator provides an estimate based on standard roofing practices, but actual requirements may vary based on specific project conditions and standards.
Should I consult a professional before purchasing materials?
Yes, it’s recommended to consult with a roofer to confirm the quantities before purchasing materials as they can account for nuances like waste, cutting, and specific project details.
Does the calculator account for waste?
No, the calculator provides estimates based on exact coverage. You should consider additional material for waste and cutting, often an additional 5-10% of the calculated amount.