how to build gravel pad under concrete
If you are just pouring a Slab without footings it is very important that you have firmly packed gravel, 4-6 and then about 6 of 3/4 stone, the 3/4 stone will allow the slab to float, and move, rather than crack when the gravel shifts.MichaeMike Â· 6 years ago. Thumbs up. 2. Thumbs down. 2. 1 comment. Loading ...f the soils are wet, or have a great deal of clay and therefore do not drain well, sand will actually keep moisture close to the underside of the slab by capillary action. You do not want this. Gravel provides pockets or voids for the water to travel down away from the concrete.