The Mechanics of Permeable Pavers Installation
Installing pavers in a driveway or parking lot is a specific process, one any customer should understand well. Laying pavers has a process, an exact science to create a finished surface that will last a century or more.
Permeable driveway and parking lot pavers can be installed anywhere where the ground beneath them allows water to seep through it and into the groundwater system below that. This covers the vast majority of commercial and residential real estate developments.
Preparation for Laying Pavers
How to lay pavers is a step-by-step process. The first step is to engineer the depth of the system. The permeable pavers are only the top layer of a very impressive, detailed system. Below that is a bed of small, gravel stones. Below that is another bed layer, this one of a larger aggregate stone. Each site will be different depending on how much rainwater the site receives, how much traffic goes over the surface, etc.
When experts install a permeable system, a lot of specialist work is done to examine the “lay of the land” so to speak, and to decide what kind of permeable system to install in preparation for laying pavers. The final decision will be based on those survey results. The three most important factors to consider in this engineering step are the soil present and their permeable test, how much traffic will be going over the system once it is installed, and how much rainwater the system will receive annually and seasonally.
The next step is to remove any current, dated paving system. We are starting over fresh here, and as the prospect of laying a permeable paving system over an existing system would completely defeat the purpose of its permeability, driveway removal is key here. Driveway demolition is accomplished with heavy equipment such as jackhammers, bobcats, etc. Permeable paving installation crews will make quick work of any existing, dated driveway system.
Now its time to put our survey and decision-making efforts from the first step into place. In this step, the existing site is excavated to the desired depth, all depending on the soil type present, annual rainfall amounts for that geographic area, and level of predicted traffic that will be using the system in the future. Areas with heavy rainfall will need to be excavated deeper. Soils composed of gravel and sand drain better, and do not need to be excavated as much. Heavy, clay earth needs to be excavated more. Here again, experts can determine the exact depth needed in driveway excavation depending on the factors present. This step sets the stage for the paver underlayment.
The next step is to compact the remaining soil bed after excavation is completed. Heavy equipment such as a roller or plate compactor is needed for soil compaction because the remaining soil bed must be well compacted and stable before aggregate rock bedding layers are added on top of it. A ground compactor is used to ensure the driveway pavers themselves will rest level with each other.
Installation of the Geotextile
Next up is the installation of a geotextile. A geotextile is a non-hazardous, permeable membrane that rests between the soil and the first layer of rock. The purpose of a geotextile is to prevent the first layer of aggregate rock that's about to be poured into the excavated system from mixing with the soil, thus reducing the efficacy of the system. After the soil compactor machine has done its job, the geotextile can be lain throughout the excavated site, resting against the floor of the newly excavated depression and coming up the sides of it.
In the next step, the first layer of larger, aggregate rocks, called the “sub-base” material is installed, filling the existing excavation to a depth of no more than six inches. This aggregate base layer will fill the lion's share of the excavated space. Once filled, a compacting roller machine is used to compress and stabilize this layer of base rock as well. The rock bed will compact significantly below the previous, six-inch mark, which is fine. A specialty tool is used for this compacting process as the crushed aggregated base cannot be compacted properly by hand.
Crushed Gravel Layer
Next, a layer of smaller, crushed gravel stone is installed on top of the first layer. In this step, four to six-inch layers are put down, then compacted with the roller machine, then another layer is installed on top of that. This is also called the “leveling base” as it serves to create an immaculately level surface for the pavers.
Final Gravel Layer
Finally, a two-inch layer of very, very fine, almost micro-grain, #57 crushed gravel is used as the final bedding layer, compacted and flattened in the same way as the above steps so as to create a smooth surface for the paving stones themselves. This gravel is similar to pea gravel but is finer and better suited for leveling. It is important to use #57 gravel for drainage as it is the first rock layer that any water will come into contact with after passing through the permeable pavers themselves. A gravel stabilizer is used to level out this final layer, finally making the system ready for permeable pavers.
Installing Permeable Pavers
In the next step, the installation crew and homeowner or business owner really begin to see the project come together, as now the permeable pavers themselves are laid out, one at a time, in a preselected pattern. This is where it “all comes together” in installing permeable pavers.
Installation crews must be careful to “edge-in” the driveway or parking lot perfectly with special pavers called “border pavers.” These pavers act as restraints, helping the rest of the pavers to hold their form. The rest of the pavers, called “field pavers,” are expertly laid in a pattern throughout the rest of the space, leaving small, one-eighth inch gaps between each paver to allow for water runoff.
Fine Grain Stone for Pavers
The last step is to sweep a fine-grain, #89 stone for pavers into the cracks between the pavers. This is one of the finest grain stones one can get without getting into various sands. Block paving, fine grit stone is key for water seepage between each paving stone. This process involves using the exact right amount of micro-stone for the total square footage of pavers, and plenty of push-broom effort to work the tiny stones into the cracks in a uniform way.
Once the installation process is finished, contractors will test the system by rushing a massive load of water over the new system, watching to ensure that the water is permeated through the stones and into the aggregate bases below. That is the basic process for expert installation of permeable pavers!
Frequently Asked Questions About Permeable Pavers
If you're looking around the Nashville area and asking, “Who's the best paving contractor in Nashville?” then look no further than Smart Scapes LLC. We will help you in all of your hardscape and landscaping needs with our expert designers and our master craftsmen, all backed by years of experience and our own guarantee of excellence.
Want to know more? Check out our FAQ below, or feel free to give us a call at (615) 422-5263 (LAND) to speak with our staff.
- How long does it take to accomplish all of the installation steps listed above?
- That depends entirely on the size of the job at hand. A permeable-paved residential driveway can be completed in a matter of a couple days. A larger commercial job or parking lot can take up to two or three weeks.
- What is the cost difference, permeable pavers to traditional concrete/asphalt?
- Depending on the products used, traditional paving asphalt is about half the price of a well-done permeable paver system. However, an expert-installed permeable paver system will outlast the lifetime of the owner (never having to be replaced) and will not require any water runoff systems or countermeasures (a cost-saver in the long run).
- Where can I use permeable pavers?
- Anywhere that you would use concrete, asphalt, or flagstones. As long as the surface is not a high-speed roadway or a steeply-graded path or road, permeable pavers can be used as an aesthetic and eco-friendly alternative to traditional asphalt and concrete.
- How are permeable pavers eco-friendly?
- Permeable pavers direct water back into the ground where it belongs. Unlike asphalt and concrete which direct water off of the paved surface and into storm drains, where it does not belong.