As trends continue to develop and evolve in landscaping, its likely you’ve heard of decomposed granite. Commonly referred to in its abbreviated form, DG, it has become quite popular in modern landscape designs. Not only for its aesthetic allure, but also for its functionality and cost-effectiveness. You may have considered using decomposed granite in your landscape, but what exactly is this hardscape material?
Starting off as solid granite stone, the rock decomposes into finer particles after rain, wind and temperature conditions continue to weather it down. For landscaping use, the gravel pieces are usually three-eighths of an inch or smaller. The gravel is then compacted into a semi-hard, but permeable surface. DG is an excellent option for paths, driveways, patios and even large areas of commercial installations like playgrounds and trails. As an organic material, its natural appearance is appealing to many types of clients and it can also help contribute LEED points for certifications in the construction industry. One of the drawbacks of DG is that it can erode over time or become soft after a rain event, potentially tracking into your home on the soles of shoes. Fortunately, there are many binding options that can help secure your DG in place while protecting against the elements.
Available in a range of hues including red, black, gold and gray, crushed granite also varies in three main types of installation methods. We are fortunate here on the Central Coast to have both grey colored DG that comes from the Aromas Granite Construction Quarry and gold colored DG from the Felton Granite Rock Quarry. Natural, or loose DG can be used as a wood mulch replacement for distributing around trees and garden areas. It can also work great in a bioretention basin where wood mulch wood be washed away by seasonal flooding. Since loose DG does not contain any stabilizers, it is best placed in low traffic areas where it won’t be tracked indoors. Stabilized DG is a mixture of gravel with a light binder which helps the material hold its form more than its natural state. Most patios and pathways are installed with a stabilized granite as it is longer lasting, more resistant to erosion, and its gritty texture provides traction for safe foot travel. Resin-coated DG will produce a hardened surface which works well for driveways as it keeps the granite in place, creating an asphalt-like exterior. Though it may be the most durable of the granites, it is also the least permeable and will not allow for proper drainage.
Over the course of my career I have encountered various questions about the different types of DG stabilization and what is most effective. The best option is to mix in a binder with the product before installing the DG. The longest lasting and highest quality product on the market today is called GraniteCrete. This patented binder combines with water and DG to create a concrete-like surface that is also permeable. It can be used in almost any application and while it is on the more expensive side due to the labor-intensive mixing process, the end result will last for decades. The next step down is a spray-on stabilizer that is applied atop the DG before compaction. Install the granite into your hardscape area, spray on the stabilizer as directed, and then compact for a finished patio, walkway or playing surface. The spray-on stabilizer can lose its grip or be washed away after a few years of rain fall due to the fact it’s not mixed in like the GraniteCrete. But it is a lower cost and less labor consuming process. Lastly, stabilized DG can be accomplished by simply mixing in Portland cement, mortar or another type of concrete material. While this is not advised for commercial application, the average homeowner with a few bags of concrete laying around may be able to stabilize their DG without much added cost. You can create the mixture in a wheelbarrow at a rate of 15:1 DG to concrete, then spread the material down, water it in and compact it. Be mindful that the concrete you use may change the color of the DG, but depending on the application this could be a quick and easy way to stabilize your DG.
Decomposed granite itself may be a simple landscaping element, but the application of anything beyond loose DG is not quite as easy. Professional help is strongly recommended since proper equipment and preparation will set the groundwork for a successful installation. Some of the additional steps of the install may entail edging, grading, and laying down base rock or root barriers. Don’t forget the use of a compactor. To ensure the material will stay in place, the gravel must be compressed firmly into the ground and this is difficult, if not almost impossible, without a granite compactor.
I hope you don’t take this naturally occurring, local granite for granted, but instead are able to find a way to incorporate it into your yard or project site. If you have large redwood trees that are heaving up your concrete walkways, replacing those with decomposed granite can make it much easier to fix and eliminate tripping hazards. Another helpful idea is under your trashcan storage area of your driveway. These spots are usually weed infested and hard to keep clean, but not if swapped out with a low maintenance patch of DG. However little or large your project may be, make your landscaping rock with decomposed granite!