All About Decomposed Granite
Decomposed granite is often referred to as granite fines, crushed granite, and DG. You have likely seen it on park trails, bocce ball courts, and ball fields throughout the area. DG can be used for informal patios, fire pit areas, garden paths, as a base for putting greens, horseshoe pit areas, & as a joint product for flagstone/pavers.
What is it?
Just as the name suggests Decomposed Granite is the eroded form of natural granite. This eroded granite is then further crushed and screened to a 3/8 down to dust size. The chemical properties of DG allow it to harden and solidify once wetted and compacted in an area. Organic binding products are typically added within the mix to further aid in stabilizing and hardening the product to handle foot traffic and natural erosion. For this reason, most applications of Decomposed Granite will be stabilized. The DG we carry at House of Rocks is stabilized at the quarry to ensure even distribution and less work on-site.
Colors
Like most stone products, different areas of the country will provide different colors of rock. As a general rule, the further away the source granite is from your home, the more expensive it will be.
Installation
The complete install will require 6-7” of excavated depth overall. Installation specs call for 2-3” of compacted base material with 3-4” of Decomposed Granite on top for maximum stability.
- Check with 1-800-DIG-RITE in Missouri or 811 in Kansas to have your utilities marked
- Excavate the desired area to the length and width desired at a 6-7” depth
- Edge the area to contain the DG. We suggest steel edging or natural stone edging but you can also use polymer, concrete, or pressure-treated wood.
- Compact the soil in the newly excavated area. A steel roller is recommended but a hand tamper can work for smaller areas.
- Weed barrier is not recommended
- Sub-Base installation. Also known as AB-3, crusher run, or road base, this is a crushed gravel that contains ¾” size gravel down to a dust. This sub-base will be vital in maintaining the structural integrity of the area. It is recommended to install at minimum a 2” sub-base. Coverage rules are 100 Sq. Ft. of coverage per ton. So if you go a full 4” the coverage will be reduced to 50 Sq. Ft. per ton. Moisten the material, spread, further moisten with a hose, and compact. For 3” or 4” depth, it is best to lay down half the material (1.5” for 3” depth or 2” for 4” depth) and compact it before adding your additional layer.
- DG Installation. Coverage rules are the same as with AB-3 (75 Sq. Ft @ 3” or 50 Sq. Ft. @ 4”). Again, compact in ½ depth layers to ensure proper compaction. Spread the decomposed granite so that there is a slight slope from the midpoint to the edge of the area to avoid the possibility of standing water. Thoroughly soak area with water. Water activates the stabilized to allow the area to set up properly. 25 gallons per ton is the minimum required amount.
- Allow area to settle for 6 – 72 hours.
- Spray surface with a fine mist and apply the roller. Mist again after compacting.
