Now that the summer is fast approaching it is time to start thinking about your outside spaces. This patio is twenty years old and is beginning to show its age. The patio slabs have sunken in places and have become uneven in high-traffic areas. It’s time to pull up the old pavers and lay down a new patio.
When the original house builders laid the patio they put down a very thin sub-base of hardcore and then laid a thin layer of sand on top without compacting the earth underneath. This has led to the slabs sinking and becoming uneven in places. See the picture below.
The first part of the project is to pull the slabs up and prepare the groundwork. This will involve taking off the old sand base layer and digging out the hardcore sub-base and some of the earth below that to give enough depth for the sub-base, base, and slab layers.
This will allow for a new sub-base of 100mm of sub-base Type 1 MoT. MoT stands for Ministry of Transport which is the specification for the type of hardcore used for sub-base layers also known as DoT or Department of Transport. On top of Type 1 will go a base layer of cement to a depth of 40mm.
The base layer will be made up of 3 parts sharp sand and one part cement with the slabs being laid on top of the base layer. The depth of the slab should be taken into account as well to allow for a gap of 50mm if possible below the level of the damp proof course (DPC) so that the risk of water penetration into the brickwork from the splashback of droplets against the wall when it rains is minimized.