How much fall? Post your questions and get answers regarding all areas of drives, pathways and patios

[SandMan]

Just wondered how much fall would you allow for say 12m long driveway? so much per meter? Is there a difference in fall between tarmac and block paving? I've seen some company's put them in level cause they belive the water would soak through the brick pavers.

[thedoctor]

Water should not be allowed to soak through anything used as a driveway. See our project on freeze thaw action. Just a slight trickle of water through a sub base can cause subsidence under the drive. Block paving should have slightly less fall than tarmac as tarmac tends to form shallow dips regularly and water does not run off so quickly whereas the chamferred edges of paving bricks form channels and the water runs away well. The slope required for tarmac can sometimes be as much as 1 in 50 wehereas with pavers we tend to work to 1 in 80. Over 12m or 12000mm this = a fall of 240mm with tarmac and 150mm with pavers.