There are many reasons that paver contractors, like us here at Bahler Brothers, dig up so much ground for our customer’s patios. The biggest reason is that in order for a paver patio to last, it must have a good base. The base must be free of biodegradable matter such as roots and other fill matter.
Base material is usually about eight to twelve inches thick, depending on the type of existing soils at the customer’s home. Base material consists of ¾ inch processed gravel. If the soil exhibits clay-like conditions, then the base must be deeper. In some cases, on a paver driveway, you may have up to two feet of base material.
The base material must be compacted to approximately 98% compaction, according to Interlocking Concrete Paver Institute (ICPI) standards. This helps prevent the pavers from moving due to settling and frost heave, which can push the pavers up in the winter, if they are not installed correctly. This thick base also helps keep the paver restraint/edging in place. We use a non-galvanized ten-inch spike to “nail” the edging into the gravel. The reason we use a non-galvanized spike is because we want it to rust. When it does so, the gravel will grab onto it much better, causing it to have firm stability. This prevents the pavers from shifting left-to-right. We need to keep them as tight as possible in order give the pavers the strength and proper interlock.
Another reason that we may dig up a lot of ground is if the patio needs to meet a certain grade in the yard. Generally at a minimum, the patio should meet the house at about six inches below the threshold of the door exiting the house. Then from there, the patio must have no less than 3/16ths pitch out to the yard or a drain. This means that the height of the patio must drop at least 3/16ths of an inch every linear foot in order for water to drain properly away from the house and dissipate into the lawn or drain. In order to meet these grades, sometimes it is necessary to dig out more soils to meet this criteria set by ICPI.
All of this work, though you don’t even see it at the end of the project, is very necessary for the durability of the project. We want our customers to have a long lasting patio that they will enjoy for many years without having any issues. Having a good base is one of the most important parts of building a patio, and most of all, keeping the customer happy!