How to Build a Decomposed Granite Patio

Decomposed granite patios and walkways are an easy, affordable hardscape option. For these reasons and more, they are one of the most popular types of hardscapes we build in SLO County.

A permeable patio made from DG

DG can be used to make a natural looking, durable, and inexpensive patio.

Decomposed granite (often referred to as DG) is a type of gravel that consists of small particles of granite rock. When used as a landscape product, it is typically compacted to produce a hard, stable surface. The material itself is relatively inexpensive, and the labor required to build a walkway or patio from DG is often simple and fast. This makes it a great alternative to more costly hardscape options such as concrete or pavers.

In addition to the cost savings, DG is long-lasting (if done right), permeable to rainwater, and looks great. Read on to see what it takes to complete a project using decomposed granite…

Step 1: Design & Planning

Before you do anything, take some time to plan out your landscape. Where will the hardscapes be? How will they be shaped? What are the dimensions? What materials will you use for edging? These are just a few questions you should be asking yourself as you draw out a design and plan your decomposed granite patio. Being diligent during this step will save you headaches down the road and ensure you get the best results.

Step 2. Initial Site Layout

Using masons string, stakes, or even spray paint, mark out where the patio will be. Take note of the elevations and grading adjacent to the patio to see if you need to modify those grades or install any type of retaining wall. Once it’s all marked out it’s time to grab the shovel!

Step 3: Excavation

Excavated site for patio.

Excavated site for DG patio.

Using a shovel or other digging tool, excavate the patio area to the desired depth. This depth depends on a few factors:

  1. Do you want the top of your patio to be level with the surrounding soil? Sometimes this is preferable, but often we want to have the patio slightly above in order to make room for a layer of mulch. This can make it much easier to put down a full 3-4 inches of mulch right up to the edge of the patio without worrying about having it spill over.
  2. The second consideration is soil type. Some soils require a thicker layer of DG to hold up long term. With any soil, we recommend having at least 4” of compacted DG for your patio. But especially sandy soils, for instance, may require a thicker layer, or even a sub-base to stand the test of time.
  3. What type of edging will you be using? If you are using redwood bender board, for example, you may not need to excavate much since it is about 4” wide and can rest on the surface of the ground. If you are using pavers as edging, however, you’ll need to excavate more soil to accommodate the base for those pavers as well as the extra depth required to meet your 4” minimum for the DG.

Consider the above factors to determine how much soil you should dig out. Make sure the excavated site has a smooth, even surface, and is graded slightly away from the house or other structures.

Step 4: Install Edging

Hopefully by now you already know what type of edging you’ll be using. We commonly use redwood bender board for DG patios, since it is unobtrusive, easy to use with many different patio styles, and holds up well over time. You can also use steel edging, pavers, boulders, and more. Look for photos of DG patios online for more inspiration.

Because the installation procedures for each different edging type is outside the scope of this guide, we’ll move on to the next step. One word of advice though with edging… use your level! Make sure to double check the level and elevations of the edging so that the whole patio isn’t off kilter.

Step 5: The DG

Finally, we get to the DG. If everything has gone well up until now, this part should be fairly easy.

Let’s start with how much you’ll need. The easiest way to determine this is to take the square footage of the patio and the depth of the DG, and enter them into an online landscape materials calculator. This will spit out the amount (in yards) of material you need. Remember, the DG will be compacted, so you’ll need to order slightly more to accommodate the decrease in thickness as it gets compacted.

Pouring DG into patio

Spread and compact the DG in even layers.

Once you have the decomposed granite, you’ll spread it over the patio area in lifts. Lifts are simply incremental layers that allow you to compact only a small thickness at a time. We recommend laying down and compacting your DG in lifts of 1.5-2” at a time until you have your full thickness. This method makes for a much more stable and long-lasting patio since it ensure the bottom most layers get fully compacted instead of just the top.

As you spread out your DG, make sure the layers are smooth and even. Wet each layer with a hose until it’s moist (not soaking wet), and then run a plate compactor over it to tamp the DG down. You can rent plate compactors from almost any tool rental store, and they are quite easy to use. Just make sure you have someone helping you because they are heavy and difficult to move!

Once each layer is fully compacted, move on to the next layer until you are at full thickness. At this point, your patio should look pretty much complete and the DG surface should be extremely hard.

Step 6: Finishing Touches

DG patio with fire pit in landscapingTo finish up, you may want to use a broom or leaf rake lightly over the top of the DG to loosen up the surface for a more natural look. In addition, take some time to clean up your work area of any stray DG, building materials, and dirt.

That’s about it! Now you have a brand new decomposed granite patio to enjoy for years to come. Note that this same procedure can be used for other DG hardscapes such as walkways.

Decomposed granite is an easy, attractive, and cost-effective choice for your next patio. If you have questions about the information above or need some help with your patio, feel free to contact us.