How to lay a patio
During the few days of sunshine we’re having this summer, you may not automatically consider laying a patio.
While this should be a straightforward DIY task taking up a few days of your time, there are risks and consequences if you don’t take care at key stages of the job, especially if close to the house.
However, the task should be within most people’s reach, requiring some basic knowledge and the strength to be able to lift and move paving slabs.
The first step is producing a detailed sketch of the proposed patio. This should clarify what’s to be done and the outstanding issues to be overcome. For example, the abutment to the house, fencing, manhole covers and walls and even trees or bushes.
You must calculate accurate dimensions for your patio and the number of slabs that will be required. Always take into consideration that some slabs may be damaged during cutting or laying. If you choose different sized slabs, be aware this could complicate the process.
The basic tools will be a semi-stiff brush, builders’ square, bucket, cement, club hammer, hosepipe, pointing trowel, screed float, spade, spirit level, sponge, string, wheelbarrow and wooden pegs. You may also need to hire from your local DIY store a unit to compact the hardcore.
The patio should have a gradual slope away from the house for easy drainage. Additionally, the surface must be at least 6in (150mm) below the damp-proof course to avoid rain splashback that can cause internal dampness. This can be awkward without preplanning, especially if the patio is laid around more than one side of the house, or includes steps.
First off, mark out the area with the builders square, pegs and string. The pegs, connected by the string, should reflect the three levels of the hardcore base, bedding mortar and slab thicknesses. You must check that the upper surface aligns with other levels for manhole covers, paths, and any existing slabs.
All existing surfaces should be removed down to a depth of 6in (150mm). It is recommended that a hardcore base is used to a depth of up to 3in (80mm) although sometimes the compacted earth is sufficient to omit this stage. Sheets of membrane to prevent weeds growing between the slabs over time can be laid at this point.
Once the first surface is compacted to provide a sound, solid base, apply the bedding mortar in a mixed ratio of 3:1:1 (building sand: soft sand: cement). This should be laid in an even amount to allow the laying of a line of slabs.
The position of the first slab is vitally important as the basis for all that follows. Start adjacent to the house, securing each slab with the club hammer and with wood to protect it. Check all angles, alignments, levels and slopes regularly as you progress.
After a day, the gaps between each slab can be filled with a semi-dry mortar mixture of four parts building sand to one part of cement using trowel. Remove any surplus mortar and traces of cement before it dries out.
The patio should then be ready for use a day later.