Laying A Patio

This is the most important part of any garden project. You need to work out exactly how much you want to spend on your patio, which products you are going to use, what features you plan to include and how long you want to spend building it. When you have done that, draw up a plan of how you want the patio to look, using either an imperial or metric scale.

When drawing up your plans, remember:

You need to find a dominant line, such as a house wall or garden fence, then work away from it, using it as your base line.

Make a note of the damp proof course and potential for water run off, as you must ensure that you allow adequate drainage and a slope away from the house to prevent water from collecting against the building.

You will need a few basic tools, such as a trowel, spirit  level and shovel. If the project is fairly large, you should consider hiring a cement mixer and angle grinder. Never ignore safety instructions when using this equipment.

The choice of paving and garden products available is large, and which one you use depends on your personal taste and the style of the garden. For example, Bradstone  have a very wide range of paving products to suit almost every taste.

Having planned your patio, you are now ready to prepare the ground.

Preparing the Ground
Equally as important as the planning stage, how well you prepare the ground will reflect on how good your finished product looks. Take your time to follow these guidelines.
Allow at least 150mm below the damp proof course and dig down another 150mm  for the patio and foundations. This applies to the whole area to be paved.
Cover the entire area to be paved with a foundation mix of one part cement to six parts of sandy ballast. This should be consolidated with a length of timber, ensuring that the foundation is even to running levels, with no high or low spots.
There should be a slight slope, or crossfall away from the house. You can set pegs at appropriate intervals to help determine this crossfall, using a spirit level to ensure that each peg is level with its’ neighbour.
You can set a fall, using a straight edge piece of timber and a spirit level, and a second peg set into the ground against the level peg. By gently tapping the second peg to a point slightly lower (or raising it slightly higher), the second peg will determine the crossfall. Paint or otherwise delineate these pegs to avoid any confusion, say, white for ‘level’ and ref for ‘crossfall’.

You should aim for a crossfall of around 1 – 200 as a minimum. (If you set pegs 2 metres apart, and raise or lower the second peg by 10mm across the 2 metre length, this will give you a 1 – 200 fall)
At this point, you are ready to lay the paving.

Laying the Paving
Ensure that the paving slabs are stacked on edge, not flat, to prevent damage by cracking under weight.
The mortar mix should be no weaker than one part cement to four parts soft builders sand (not sandy ballast or sharp sand) The mixture should be sticky but not too wet (or dry).

Lay the first slab in the corner of the area to be paved, using five or more trowel spots of mortar, depending on the size of the slab. There should be sufficient mortar placed under the slab to ensure that the whole of the slab is covered in mortar once it is pushed into position, i.e. a full mortar bed, not a number of spot beds which will hold water between the underside of the slab and the concrete base. This water will expand during frosty weather and lift the slabs loose.

The slab may be bedded by gently tapping down from the centre outwards, not corner to corner as this will result in a dome shaped mortar bed. Using string lines to ensure accurate lines and levels, progress the laying of the paving.
If you are using a random pattern ensure that the correct balance of sizes and colours are used as laying progresses, to avoid too many units of the same size or colour variation. (Too many small slabs, too many large in one area, too many light or dark colours if using a natural paving slab).

Some regular sized products lend themselves to the use of spacers to ensure that all joints are uniform. These may take the form of (say) 13mm battens or plastic strips.

If you are laying a large area, take the slabs from one or more pack to ensure colour variation, even if nominally the same product. Batches can vary even very slightly due to age and length of storage/manufacture.
Once the paving is complete, seal off the area to prevent anyone from walking over the work – including large dogs. If you think that a slab is cracked/loose or you are not happy with in any way, now is the time to change it.

For pointing, a mix of one part cement to three parts soft sand is suggested. Once again, the mixture must be carefully batched to ensure uniform colour of the mortar.
The mixture should be moist enough to roll into a ball in your hand, but not too wet. Ensure that the paving is dry  before you commence pointing work to prevent staining.

Place a small amount of pointing mortar on to a piece of board and fill each joint with a pointing trowel, ensuring that the gap is fully filled with no low spots or soft areas.
Press the mortar into the joint using a piece of rounded metal, such as a bucket handle, ensure the mix is well compacted to prevent moisture or weed seeds from getting into the patio.
With some products, especially man made concrete paving, you may wish to match the colour of the concrete mix with colour dye.

Careful planning is the secret of success. If you choose to use more than one type of slab, check the measurements of each type before you start planning, as they may vary in size. Some products that are nominally 45cm x 45cm may actually be 44cm x 44cm, and whilst the difference may sound unimportant, it may have a major impact on the design over a large area.