How To Cut Paving Slabs

There are a few different methods for cutting paving slabs. Below we will outline the most common approaches, which include using power tools and hand tools.

Cutting paving slabs with an angle grinder

Using an angle grinder with a diamond masonry blade can be one of the most effective methods for cutting paving slabs. It’s widely accessible for both DIY and professional landscaping and best used on concrete and sandstone.

Step 1. Preparing the slab

Preparation is key to achieving a straight, clean cut. Careful measuring and marking will ensure it is accurate and safe.

• Measure the slab - using a tape measure, carefully measure the gap or area where the slab will be placed. Allow for a small joint gap (normally around 5mm, but depends on size of slab), between slabs for jointing material. Ensure measurements are correct before marking the slab as it could result in the slab being too small or large for the space. 

• Marking the cut - transfer the measurement onto the slab using a pencil (or marker). Place a straight edge or ruler along the marks and draw a straight line across. This should be clearly marked and easy to see as it will guide the blade during the cutting process.

• Slab placement - the slab must be on a stable and secure surface for cutting. Common support methods include laying it on a workbench, on the ground or across two concrete blocks. The area that will be cut off should overhang slightly so that the blade can pass through without hitting the surface, so it’s vital to take this into account whilst choosing your support.

Once you’re happy with the preparation steps, it’s a good idea to take a moment just to check that everything is secure and ready to go. Make sure the slab is appropriately measured, the cutting line is clearly visible and the slab cannot move or slide when cutting.

Step 2. Scoring the slab

Although not essential, it’s a good idea to score the slab before cutting. The blade can create a shallow groove along the marked line which will act as a guide. It can improve the accuracy of your cut and helps to create a clear path.

Holding the angle grinder firmly with both hands, start the grinder and allow the blade to reach full speed before making contact with the slab. Position it directly on the marked cutting line and gently guide the blade along to create a shallow groove (about 2mm deep). Ensure the cut is light and controlled to avoid it penetrating too deep. The goal is to only mark it as a guide, and not to cut immediately.

Once you’ve made the groove, it’s a good idea to check to ensure you’re happy before proceeding. Ensure it follows the marked line and the line is straight and visible. 

Step 3. Cutting the slab

The key to an accurate cut is patience and control. It’s crucial that the slab remains stable and properly supported throughout the process. The part of the slab that’s being removed should be overhanging to allow it to fall away once the cut is complete. However, the main area must remain fully supported to prevent the slab breaking.

Position the angle grinder along the scored groove and allow the blade to reach the full operating speed before moving it. Follow the line carefully, gradually deepening the cut as you go. Most paving slabs require a few passes depending on the thickness and material. 

For a cleaner cut, you can let the blade do the work instead of gradually deepening the cut. Ensure consistent cutting speed and avoid any sudden movements or forcing the blade into the slab. Let the blade work naturally for a controlled cut. 

If you have a thicker paving slab you may need to rotate it so the blade can cut through from both sides. Make sure you’re careful in aligning the blade with the existing cut line to avoid it being uneven. 

Once the angle grinder has cut all the way through, the off-cut should naturally separate. Use a hammer or chisel to help release it if it remains attached. 

If the edge appears rough you can use the angle grinder to lightly brush along the edge to smooth the surface. An alternative is using a sanding block to create a cleaner finish. 

Step 4. Checking & cleaning the slab

Before placing the slab permanently it’s important to check that it fits correctly in the area. Carefully move the slab into position and check that it sits evenly and there is consistent joint spacing against each edge. 

If the slab is too large, then at this point you will be able to adjust it by trimming the edge with the angle grinder. If the slab is too small, then you may need to start again with a new slab, or adjust the jointing area. 

Cutting paving slabs produces a lot of dust and debris which needs to be cleaned up before installation. Brush the dust from the surface of the slab and wipe down the edges if necessary. Make sure to sweep the area to remove any loose material before putting the slabs into position. Keeping the slabs clean helps prevent dust from interfering with the jointing material. 

Advantages and disadvantages of using an angle grinder to cut slabs

Advantages

• Effective cutting method

• Suitable for most materials

• Allows both straight and curved cuts

• Easily accessible tool (that may already be pre-owned)

Disadvantages

• Large amount of dust and debris

• Higher risk of injury (compared to using hand tools)

• High noise levels

Cutting paving slabs with a hammer & chisel

Cutting a paving slab with a hammer and chisel is best for making smaller adjustments. As a more traditional method, it works by creating a controlled line in the slab instead of grinding through the material with a power tool. This technique tends to require more time and physical effort than using a power tool, but can be a cost-effective way of cutting a paving slab.

Step 1. Measuring & marking the slab

Measure the space where the slab will be installed, leaving around 5mm (dependent upon material) for the jointing material. Ensure careful and accurate measurements are taken to avoid cutting the slab too small.

Using a pencil, mark the line you wish to cut with a straight edge (or ruler). This line will act as a guide during the scoring process, so it’s vital that this is accurate.

Step 2. Scoring the slab

Before proceeding, ensure the slab is positioned correctly on a firm and stable surface (such as a workbench). The marked cutting line should be positioned near the edge of the support to allow the off-cut to separate easily when cut.

To begin scoring, place the cutting edge of the chisel directly on the marked line. Hold it vertically (or at a slight angle), and strike the top of the chisel firmly with the club hammer. Then, move the chisel along the line, repeating the process as you go. By doing so, you will create a series of small indentations along the marked line which over time will connect to form a continuous groove. Consistency is really important during this stage as the chisel should be struck evenly along the line to remain uniform in depth. 

Step 3. Splitting the slab

Place the chisel firmly in the groove and strike down with the hammer. The force used when hammering should weaken the line, causing the slab to crack and separate. If the slab doesn’t break, then repeat the process until the crack forms. Sometimes light tapping along different sections can help it split.

After the slab separates, the edge may appear rough or uneven which is normally when splitting. To improve the finish, lightly chisel and tap along the edge to help remove fragments. The overall appearance may not be as smooth as a power tool cut, but the edges can be hidden by jointing material or additional slabs. 

Advantages and disadvantages of using a hammer and chisel to cut slabs

Advantages

• Requires simple tools

• Produces less dust than power tools

• Suitable for small jobs and adjustments

Disadvantages

• Timeconsuming

• Physically demanding

• Less precise (than a using a power tool)

• Edges may remain rough or uneven

Cutting paving slabs with a power saw

Cutting paving slabs with a power saw is a common method and usually provides the cleanest cut of all the methods mentioned. The type of saw you use depends on the material, thickness of the slab and your level of competence in using the tool. 

Step 1. Choose the right saw

There are a few different options for the type of saw you can use to cut paving slabs. The most common types are mentioned below:

• Tile saws (also known as wet saws) are best for porcelain, ceramic and natural stone. They usually provide an extremely clean cut with minimal dust and debris. 

• Circular saws work especially well for straight cuts, and are best used on concrete or sandstone slabs. You would need to ensure the correct blade is being used as circular saws are more commonly used for wood.

• Cut-off saws (also known as a disc cutter) are best for straight cuts.

The main difference between the tools is that a tile saw uses water to cool the blade which reduces dust, whilst circular saws and cut-off saws are typically used for dry cutting.

Step 2. Preparation

It’s important to ensure the slab is accurately measured, marked and prepared before cutting.

• Measure & mark - measure the space where the slab will be installed and transfer onto the slab using a pencil or chalk. Use a straight edge (or ruler) to draw a clear cutting line.

• Level surface - it’s important to place the slab on a saw table, or flat surface before cutting. This is to ensure the blade goes through effortlessly without damaging the surrounding area. 

• Correct blade - when using any type of saw, you need to ensure the appropriate blade is being used before cutting.

• Water supply - if using a tile saw, you need to ensure the water tray is full, or connected to the water supply before use. Never operate the saw without water flowing.

• Safety & PPE - wear eye and ear protection, and keep hands clear of the blade at all times.

Step 3. Scoring and cutting

Before fully cutting the slab, make a show scoring cut using your saw. Allow the blade to reach full speed and then carefully guide the blade along the marked line. Cut around 2mm deep to create a guide groove to help maintain accuracy during deeper cuts.

Once you’ve built gradual depth, you should be able to finish the cut. As you near the end, ensure both sides are supported to prevent snapping or breaking off before it’s ready. Once separated, you will need to inspect the edge of the slab. If it appears rough, then you can run the blade lightly along the edge, or gently sand to smooth it out.