When to Use Sand or Rock Bases for Patios

Sandy Soil

• Most brick patios are installed with layers of both sand and rock for the longest lasting installation, but in some cases it isn’t necessarily a requirement. If you are living in an area that already has sandy soil, you can generally use a layer of crushed rock underneath the brick. The sandy soil already provides a base of support, and as long as it is packed firm under the installation, there are no concerns.

Clay Soil

• While rock isn’t necessarily affected by water, sand is. If you live in an area that has a clay soil base you will need to use more rock than sand. This is because clay does not drain well and that backwater can soak into the sand and cause it to harden and eventually soak up clay elements. Once this happens you will have pieces that can occasionally stick up due to hard sand underneath, so sand should be kept to a minimum in these cases.

Hard Soil

• As long as the soil is dry and hard-packed, you can use a base of rough sand. It will need to be thick enough to support the pavers, but because the ground is dry and excess water isn’t an issue you don’t need the rock for drainage, and the sand can sufficiently support the patio above. You can also add a layer of rock under the sand if you want extra protection.

Climate

• The climate can affect the type of sand you use on top of your rocks. Because sand can soak up water, it is susceptible to freezing in the winter, as well as the freeze/thaw cycle in the late fall and early springs months. When water hardens it expands, which forces patio pavers up off the patio. Your best option in these cases is to use the roughest sand you can find or the finest type of rock gravel to allow for adequate drainage.