Patio Paving Step by Step: A Complete DIY Guide

Before You Start: Plan and Calculate

A well-laid patio adds value to your home and creates a usable outdoor living space. The key to a professional result is thorough preparation — rushing the sub-base is the number one cause of patio failure.

Start by calculating your materials. The paving calculator gives you exact quantities for slabs, sand, cement, and edging based on your patio dimensions and chosen slab size.

Step 1: Mark Out and Excavate

Mark the patio outline with string lines and pegs. Allow a slight fall of 1 in 60 (roughly 15 mm per metre) away from the house for drainage.

Excavate to a depth of approximately 150 mm: 100 mm for the sub-base, 30–40 mm for the mortar bed, and the slab thickness sits level with or slightly above the surrounding ground.

Remove any topsoil, roots, and organic material. The excavated base must be firm and level.

Step 2: Lay the Sub-Base

A solid sub-base prevents settling and cracking. Spread 100 mm of MOT Type 1 crushed stone (or equivalent) over the excavated area. Compact it thoroughly with a plate compactor or hand tamper, working in 50 mm layers.

The sub-base should be firm enough that you leave no footprints when walking on it. Use the gravel calculator to work out exactly how many tonnes of sub-base material you need.

Step 3: Set Edging Restraints

Install a permanent edge restraint around the perimeter before laying slabs. This prevents the paving from creeping outward over time. Options include concrete haunching, metal paving edging, or a row of slabs set in concrete.

Mix a stiff concrete bed (6 parts ballast to 1 part cement) along the edges and bed the edging into it. Let it set for at least 24 hours before laying the main paving.

Step 4: Prepare the Mortar Bed

Mix a semi-dry mortar: 5 parts sharp sand to 1 part cement. It should hold together when squeezed but not be wet or sloppy. Spread a 30–40 mm mortar bed over a small section — only enough for 3–4 slabs at a time.

Use a straight edge or screed rails to level the mortar bed to an even depth, maintaining the drainage fall you established during excavation.

Step 5: Lay the Paving Slabs

Start from a corner nearest to the house and work outward. Place each slab onto the mortar bed and tap it down firmly with a rubber mallet. Use spacers (8–10 mm) between slabs for a consistent joint width.

Check each slab with a spirit level in two directions. Adjust by adding or removing mortar underneath. Every 3–4 slabs, place the spirit level across multiple slabs to check the overall fall.

Work from the laid surface — never stand on the mortar bed waiting for slabs. If you need to access the un-paved area, use scaffold boards to spread your weight.

Step 6: Cut Slabs to Fit

Mark cutting lines with a pencil and straight edge. For straight cuts, score deeply with a bolster chisel and hammer, then snap. For a cleaner cut (especially on porcelain or natural stone), use a diamond blade wet saw or angle grinder with a diamond disc.

Always wear safety glasses, ear protection, and a dust mask when cutting paving slabs.

Step 7: Joint the Paving

Wait at least 24 hours for the mortar bed to firm up before jointing. Use a stiff mortar mix (4:1 sand to cement) or a proprietary jointing compound. Press the mortar firmly into every joint with a pointing trowel, then smooth with a jointing tool.

Brush off excess mortar before it dries. Dried mortar stains are very difficult to remove from paving surfaces.

Step 8: Aftercare

Keep traffic off the patio for at least 48 hours to let the joints cure. In dry weather, mist the joints with water for the first few days to prevent the mortar from drying too fast and cracking.

To prevent staining and weed growth, apply a paving sealant once the mortar is fully cured (7–14 days). Sealed paving is easier to clean and resists moss and algae growth.

Calculate Your Patio Materials

Get exact quantities for your project:

• Paving Calculator — slabs, sand, and cement
• Gravel Calculator — sub-base aggregate
• Concrete Calculator — for edging and foundations