Drawing up the plan
If you are laying in a random laying pattern, as we are in this example, you will need to draw up a plan for the pattern itself. The plan will tell you what quantities of each of the three sizes to order and save you money by making sure you order the exact amount. For this example, we are using Bradstone's Old Riven paving slabs in three sizes - 600 x 450, 450 x 450 and 300 x 450. All three sizes fit together to create a nice random laying pattern with a traditional feel.
Gather together the following materials:
Preparing the site
Decide what will be your top level for the patio and where you want the water to go. In general, patios should fall away from the house and be level across the house so that the water never gathers at the house and causes dampness problems. You should also make sure that the patio does not come above the damp proof course in your house.
Dig out enough soil to accommodate the thickness of the slab itself and around 30mm for the mortar bed. If the ground is solid, you can go ahead and lay onto this since the mortar bed will provide a good base. However, if the ground is still soft, you will need to dig out a little more and lay a type one base to prevent the patio from sinking in the future.
Once you have dug out all you need to, you can lay a weed membrane over the soil to prevent weeds coming through the pointing gaps in the patio. A weed membrane is not essential but it is a good idea if you want to lessen the maintenance in the future. You must use a woven membrane designed for this purpose such as plantex. Plastic is not suitable for laying paving.
Mixing the mortar
It is best to lay decorative paving onto a full wet mortar bed. Decorative paving is thinner than traditional utility slabs and a full mortar bed ensures that there is no air underneath the slab thus preventing it from cracking in the future. Using this full mortar bed method as opposed to the 'five blob' method of laying also ensures that insects such as ants don't take up residence in the gaps under your slabs.
Using the cement mixer, mix up a good 4 to 1 mix of mortar - that is four parts sand to one part cement plus, of course, enough water to give you a consistency that is stiff enough to support the slab but soft enough to let you knock it down. Mixing mortar is a bit of an art form and you might need a few practices before you get it right.
Laying the slabs
Starting at the house, lay the slabs according to your plan. Put down a few spadefuls of mortar and use your float to get it roughly level. Lay the first slab onto the mortar and check, with your tape measure, that it is perfectly parallel with the house. With the rubber hammer, gently tap the slab down into the mortar until it is level across the way and with a slight fall away from the house.
Continue laying the slabs according to your plan and mark off the slabs you have laid on the plan so you know where you are. Keep checking your work with the spirit level to ensure there are no dips which will collect water and make sure too that there are no high edges for you to trip on.
It is best to point up as you go along using the same mortar mix that you are laying onto. However, you must stop laying every now and then and carefully wash off all the wet mortar with clean water. Never let wet mortar dry onto the slabs since this will stain most decorative paving. Be especially careful along the joints to get your work as clean as possible.
When you have finished the patio, you can haunch up around it with a layer of mortar using your float. This will hold the edges in place and prevent them from slipping.
Soften the edges of your patio with gravel or planting. You can even leave out a few small slabs, as we have done, and plant low-growing matt forming plants such as thyme to break up the patio and add a little colour.
You should not walk on your newly laid patio for at least 48 hours to allow the mortar to set. To keep your patio looking great, you will need to pressure wash it every two or three years and, after you have done this, you should replace any loose mortar in the pointing gaps.
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