How many inches deep for stone under shed

3 too 4 and make sure the shed pad is level

Hi. 4 inches is sufficient on level ground. But note, gravel is not only useful for drainage, but another important reason to lay gravel is to level the area where the shed will sit. A yard can look level to the eye, but in reality it might be X inches high on one side and lower on the other. This means we'd put the shed on blocks to level the shed floor and that isn't so attractive. So over non-level ground you'd lay the gravel deeper on the low side and less deep on the high side in order to create a level gravel surface for the shed... No doubt we've complicated the answer to your simple question, but the depth of gravel depends on the degree of slope to your site. Two things: 1) Please see the "preparation" page under "services" on our website, and 2) Then please call us and we will help you get it just right. Thank you for your question.