It is incredibly important that you do not skimp on the excavation of your paver project. The base is your foundation for your project. It will determine the longevity and the likelihood of failure. Though there are some things out of our control when it comes to the movement of the ground, preparing a proper base is within our control when we install a paver project.
What Affects Paver Excavation Depth
Everything is dependent on your base and the beginning step to that is your excavation. When it comes to that base preparation the first thing we need to do is excavate for your base, bedding layer, and pavers to be installed. It is these three factors that will determine the depth of our excavation.
- Calculating Base Depth
- Climate
- Subsoil
- Traffic
- Bedding Layer and Paver Height
There are reasons why there are guidelines in the industry for the depth of your base in any paver installation. Everything from drainage to dealing with freeze-thaw cycles and to give your project the best possibility to its long term success all hinges on a proper excavation and base preparation. But in terms of the depth of your base, there are a few things that are going to affect that including:
Climate plays an important factor because in northern climates we experience freeze-thaw cycles regularly throughout the winter seasons. We need to ensure that we have a solid foundation and drainage for our paver project to minimize the affects of these cycles. Whereas in more southern climates where they do not get as harsh winters, you can get away with a little bit less of an excavation for that base preparation.
Once you have removed the topsoil in your excavation you are likely getting down to your subsoil which is something between a clay or sandy subsoil with some silt in it. Weaker and less draining soils like clay are going to require a little bit more excavation than a more free draining material, such as sand. If we are in a sandy soil, we will opt for the minimum on our range for our base material. If we are in a clay soil, we will opt for the maximum in our range for our base material.
Regardless of the base measurements, you always need to make sure that you’re getting down to the foundational subsoil. Any organic material under your base will decompose and cause settlement while also being prone to movement in the future. There have been occasions where we have dug and hit a tree root of some sort that was ground down many years ago that the homeowner did not know about that. We need to remove that entire tree root and instead of digging down 9.5 inches we were digging down 24 inches. In those same applications, we are digging out a lot of topsoil because it used to be a garden of some sort. So it is incredibly important to dig those test holes to see how far those organic materials reach down before you are hitting some sort of subsoil.
Projects like patios and walkways that experience light pedestrian traffic will differ in base depth from projects that experience heavy vehicular traffic.
With all of this considered, the measurements for our base depth in our northern climate will be a minimum of 6 inches to a maximum of 8 inches for our paver patios and walkways that experience light pedestrian traffic and a minimum of 12 inches to a maximum of 14 inches for projects that experience vehicular traffic.
Our base material for our driveways are about double the excavation depth just for that base material alone when compared to our patios and walkways.
Our excavation does not stop with just our base material. We also need to now factor in our bedding layer as well as our paver height because all of this needs to be factored into our excavation depth so that our pavers and bedding material is not going to sit higher than where our final grade is going to be. The bedding material is always going to be about an inch. You do not want to go more than 1.5 inches and you want this to be fairly uniform.
The height of the pavers totally depends on the paver that you are going to choose because there is a variety of heights. They are usually about 2 3/8 of an inch or 60 millimeters for pavers but can come slightly thinner or thicker.
Now we can add up the base depth, bedding layer, and paver height to know exactly how deep we are going to be digging.
For paver projects that experience light pedestrian traffic we will dig upwards of 9.5 to 11.5 inches which includes:
- 6 to 8 inches for the base material
- 1 inch for the bedding layer (no more than 1.5 inches)
- About 2 3/8 of an inch for the pavers (dependent on the paver choice)
For paver projects that experience vehicular traffic we will dig upwards of 15.5 to 17.5 inches which includes:
- 12 to 14 inches for the base material
- 1 inch for the bedding layer (no more than 1.5 inches)
- About 2 3/8 of an inch for the pavers (dependent on the paver choice)
Now alternative to all of this, you can actually use a synthetic base or paver base panels which reduces your excavation quite a bit. They reduce your excavation to the height of the paver, the one inch bedding layer, and the height of these paver base panels which are around three quarters of an inch. That becomes about 4 inches for an excavation depth if you are choosing a 2 3/8 inch paver height. So you can see how much of a savings in excavation these paver base panels can be for you.
One additional note for the excavation of your paver project is that you always need to excavate beyond the final paver by the depth of your base. So if your base is six inches deep, you are actually going to excavate an additional six inches beyond where your pavers will end to be able to fit in your edge restraint as well as to give your pavers a platform to sit on so that they are not going to slide off over time.