Interlocking pavers are probably the most common landscaping feature we get asked to do in Victoria BC. They are used in patios, walkways, and driveways. One of the most important aspects of installing pavers is proper base prep. Here is a quick guide highlighting some key points in the process.
Compaction
At the very bottom is going to be regular old soil. Whatever dirt was there before, you will need to compact. However, it must be dry during compaction. Wet mud will not compact properly. Ensuring the soil Is compacted means everything that goes after it will have a stable foundation to rest on. It’s best to have a plate compactor to do the compaction. Having it go over each area 2-3 times will ensure that the surface is sufficiently compacted.
Next you will want to compact road base. Road base is a mix of gravel, usually ¾” in size, mixed with “fines”, which are fine particulates. This mix with some water added in makes a great material that drains well but also provides great stability. This too must be compacted, preferably with a plate compactor. Best practice dictates compacting 4” lifts. So if you are building a driveway and need 8” of road base, you will need to apply 4” of road base, compact, then add another 4” and compact again. Otherwise the force will be insufficient to compact all 8” at once and you will have an unstable shifting layer. As a general rule, the heavier the expected load, the more road base to use. 4” for walkways and 8” or more for driveways and patios that will have for example a hot tub on top.
Sand
Some landscapers will compact sand. This doesn’t really make sense as it will just shift around. Sand doesn’t really compact. You can try and see for yourself but some landscapers swear by it. 0.5” to 1” of sand placed on top of the compacted road base is what you’ll want before placing the pavers themselves. This thin layer of sand cushions the pavers and hides small imperfections in the flatness of the road base below ensuring that the final surface is nice and even. Adding more than 1” of sand will risk shifting as too much sand is not a stable material.
Landscaping Fabric
Fabric can be used between the road base and the dirt. As written here, the actual value of fabric is questionable. If, however, you choose to put fabric down, make sure to overlap the edges of the fabric by about 6-12”.
That’s it
It’s not super difficult but the main thing is having proper compaction in the soil and the road base, having the proper base material, and using the appropriate amount for the expected load. This will pretty much ensure your pavers won’t sink in the near future. If you have any questions, suggestions, or want us to take a look, please let us know.