Concrete – Preparing The Base

It seems to me that many people think that a concrete driveway or path will cover any number of shortcuts and other sins.

Well if you want a good finish, that will last, you need to make sure that preparation isn’t skimped. Without a good base for the slab to sit on cracks will soon spoil the finished look of your drive or path.

This is what I would regard as the minimum preparation for laying a concrete driveway or path for a new home.

  1. The area of excavation, and base, should be a minimum of the area of concrete plus 150 mm all round, except where the edge is against a wall.
  2. During dry weather excavate the area to a depth that will allow for the depth of the slab plus for a gravel base of at least 100mm.
  3. Inspect the excavated surface for soft areas. Typical soft areas are water logged areas, topsoil and badly backfilled trenches.
  4. Excavate any soft areas and backfill with gravel compacted in 100mm layers with a vibrating plate.
  5. Keep people and equipment off the area and make sure surface water is not allowed to flow across the area.
  6. Lay the gravel base to the required level making sure its well compacted with a vibrating plate compactor.
  7. Cover with a polythene layer. You can normally buy this off a roll by the m at a building suppliers for small jobs. For driveways and paths you don’t have to bother about small holes in the polythene. Under a house slab its a different matter and there needs to be proper overlaps and no holes.

 

For more posts on on getting your paths and driveways correct see Concreting