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.
- 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.
- 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.
- Inspect the excavated surface for soft areas. Typical soft areas are water logged areas, topsoil and badly backfilled trenches.
- Excavate any soft areas and backfill with gravel compacted in 100mm layers with a vibrating plate.
- Keep people and equipment off the area and make sure surface water is not allowed to flow across the area.
- Lay the gravel base to the required level making sure its well compacted with a vibrating plate compactor.
- 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.