Before starting any project, it is essential to consider where the surface water will be going. Legislation does not permit water from a hard paved area to discharge onto the public road or into a communal drainage system.
All water should be confined to the property only. Ideally, you should design the paved area to allow any surface water to run off onto a lawn or the surrounding borders. Alternatively, you could create an adjacent rain garden, where the surface water will drain off. This area should typically be 10% of the total paved area.
As an alternative solution, if the design does not allow for any of the above, you could consider a propriety soakaway. This can be installed below the paved area but must be at least 5m from the house. Simple linear drainage will then immediately discharge into the soakaway. You should attempt to design the paved area with falls away from buildings typically 1:80. Once you have marked out the area to be paved, remove all topsoil and dig down a total depth of 100-150mm, depending on the quality of the subgrade. Vehicle areas should always have a sub-base depth of 150mm minimum.
The finished level of the paved area must be at least 150mm below the damp proof course of any adjacent building. However, there is an exception if you are installing bi-fold doors with a flush weathered threshold. The doors must be fitted before laying your patio. The door manufacturers should provide a specification to deal with the rainwater.