Slate is an incredibly versatile and attractive material that is most commonly used on roofs and flooring. Slate will often need to be cut to size in order to fit around protrusions or complex structures, as well as to create complete rows of tiles on roofs, but it can be a challenge to cut the slate correctly without it splitting.
How to cut slate roof tiles
So how can you cut slate roof tiles accurately and easily to create straight and even edges on your roof tiles? Read on to find out how to cut slate roof tiles with a slate cutter, how to cut slate with power tools, and how to cut slate tiles by hand.
Table of contents:
Preparation
Safety precautions
It is always important to work in a well-ventilated area when cutting slate, as large amounts of dust may be created, as well as particles flying into the air. Therefore, as well as working in a ventilated area, we’d recommend wearing safety goggles, safety gloves, and a dust mask to protect yourself, preventing dust and other particles from being inhaled or getting into your eyes.
Marking the slate
Whether you’re cutting slate with power tools or cutting slate by hand, the first step is to create an accurate mark on the slate that acts as a cutting guide. When cutting slate by hand we’d recommend marking the underside of the slate, as cutting will be easier. The mark is most commonly done using a pencil and a straight edge, or ruler, but if the pencil is hard to see, you can also use a grease pen or even masking tape.
Score the cutting line
Before beginning the cutting process, it is important to score the slate along the line marked. This will ensure the slate breaks cleanly and gives a guide for the cutting tools to sit in. Line up a straight edge such as a piece of wood along the marked line. Now score along the marked line with the sharp edge of a chisel, ensuring it remains straight and applying enough pressure to create a distinct groove, but without pressing too hard that cracks and splits occur. If you’d prefer, you can use a carbide-tipped pencil to create a more accurately scored line.
How to cut slate tiles by hand
If you’re looking to cut slates by hand, this can be done with a chisel and hammer, but it is important to note that this technique is most suited for cutting through thin slates, and may not work on thicker slates. Alternatively, you can cut slates by hand using a pair of tile cutters or slate cutters.
Cutting slates with a hammer and chisel
To cut slates with a chisel and hammer, line up a straight edge such as a piece of wood along the marked line. Now score along the marked line with the sharp edge of a chisel, ensuring it remains straight and applying enough pressure to create a distinct groove, but without pressing too hard that cracks and splits occur. If you’d prefer, you can use a carbide-tipped pencil to create a more accurately scored line.
Once you’re happy that the line has been scored, place the chisel within the scored line and use the hammer to tap the top of the chisel lightly. Continue this method down the scored line and the slate should break off along the marked line cleanly.
Cutting slates with tile cutters
Another method of cutting slate tiles by hand includes the use of a tile cutter. Tile cutters are handheld tools, similar to scissors, but these have been developed specifically to cut through slate and other roof tiles easily and accurately. 
To cut slates with tile or slate cutters, line them up with the scored line, before squeezing the handles together, and applying pressure to cut through the slate. Continue cutting along the scored line ensuring the edge created is as straight as possible.
How to cut slate roof tiles with power tools
A number of different power tools can be used to cut slate, such as an angle grinder or circular saw. These power tools are typically used on thicker and larger pieces of slate that are difficult to cut through by hand.
Cutting slate with an angle grinder
When working with an angle grinder, try to ensure your slate is clamped securely to a workbench. This will prevent movement during the cutting process, helping to ensure the line cut is straight and even.
Slowly lower the angle grinder down onto the scored line, and use small up and down movements to slowly cut through the slate. Keep the angle grinder on a straight line and move it along the slate until you reach the other end.
Cutting slate with a circular saw
If working with a circular saw, once you’ve scored the straight line make sure you also mark where the line meets the edge of the slate too.
Then place the slate onto the saw platform and place the blade above the scored line. Pull the trigger, or turn the blade on, and then lower the blade down onto the slate. Push the slate slowly along the surface of the saw machinery to follow the scored line and cut through the slate.
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