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Custom cut slate windowsills

Grey Slate and Stone Ltd manufacture made-to-measure slate window sills in  a variety of thicknesses and finishes.

Slate’s characteristics make it the ideal natural choice to protect your home. Our slate window sills are durable, with high resistance to acid and alkali. The surface is impervious, meaning water will not penetrate, ensuring the material is protected from frost damage, giving you and your home the protection it needs against the harsh British weather.

Please fill out the Enquiry form below with your requirements and one of our sales team will get back to you with a quotation.

If you would prefer to discuss your options with a member of our sales team first, please call us on 01766 514700, or use our contact form.


Stage 1


length x width

Please include includes a minimum 10mm overhang on each edge due to the fluted drip constructed in to the underside of the slate

Please choose your thickness
Choose your sill detail
Your Project

Your Details

Please provide us with your necessary details.

you can upload a list of your required window size

Specifications & Options

joggles or horns


Slate window sills manufactured to your specific size and shape. We precision cut our slate to suit your window opening with an optional wrap around joggle to each reveal. Horns are cut in to each slate end so that it sits nicely in to each opening, and rendered. We do not recommend joggles for a stone clad build as the slate will sit inbetween each reveal.

profiled weathered slate sills

Profiled slate sills

Manufactured to your specific sizes, we precision cut and profile our slate to suit your project. Our profiled slate sills are all bespoke made with a seat or flat top for your window to sit on and a machined slope so the weather will not penetrate your home, with a fluted drip groove as standard. In order to produce this product we do recommend a minimum of 50mm thickness.

Plain Straight Slate Window Sills

Standard Sizes

Regarded as the most cost effective solution to your build, our plain straight slate window sills are available in most widths and lengths; rectangular in shape with a good choice of thicknesses. There are two types of finishes, a riven/cleft finish, or a smooth fine rubbed surface; all precision cut to your bespoke window or opening sizes.