Decomposed Granite DG: Properties, Uses, Installation

Decomposed granite (often abbreviated as DG) is a type of granitic rock that has weathered to the point of breaking down into very small particles and gravel-like material known as grus. This erosion process breaks down the granite into smaller and weaker pieces, resulting in a product that typically has a sandy or gravel-like texture. The size of the particles in decomposed granite can vary depending on the level of weathering, but it's usually less than 3/8ths of an inch in diameter.

Granite is a hard igneous rock that's resistant to weathering. However, over thousands of years, exposure to rain, wind, and extreme temperatures can cause the rock to crack and crumble. This natural breakdown process produces decomposed granite.

Decomposed Granite Colors

Decomposed granite comes in a wide range of colors, including:

Tan, gold, and brown: These are the most common colors of decomposed granite. They are a good choice for a natural look that will blend in with most landscapes.

Gray: Gray decomposed granite is a good choice for a more modern look. It can also help to reflect heat, which can be beneficial in hot climates.

Red and pink: Red and pink decomposed granite can add a pop of color to your landscape. They are a good choice for use in areas with warm climates.

Black: Black decomposed granite is a dramatic choice that can be used to create a formal look. It can also help to suppress weeds.

Decomposed Granite Colors

Properties of Decomposed Granite

Decomposed granite is known for its several beneficial properties, including:

Permeability: Because of the spaces between the particles, DG allows water to drain through it effectively, reducing runoff and promoting healthy drainage in your yard. This permeability is beneficial in areas that receive a lot of rain or have poor natural drainage.

Compactability: DG can be compacted to create a stable and supportive surface for walkways, patios, and driveways. When compacted, decomposed granite forms a dense and stable surface that can withstand foot traffic and vehicle weight.

Mineral Composition: DG inherits its mineral composition from the parent granite rock, typically comprising quartz, feldspar, and mica. The proportions of these minerals influence the color and overall aesthetic appearance of the material.

Variety of colors: DG comes in a variety of natural colors, including browns, reds, golds, grays, greens, and tans, allowing for creative design in your landscaping projects. The natural color variations of decomposed granite can add a touch of beauty and complement the overall design of your outdoor space.

Low maintenance: DG requires minimal maintenance compared to other landscaping materials like concrete or pavers. DG does not crack or heave, and it requires occasional weeding and topdressing to maintain its appearance.

Fire resistant: Decomposed granite is a fire-resistant material, making it a good choice for areas around fireplaces and fire pits. Because it is not flammable, decomposed granite can help to create a firebreak around your home.

Discourages weeds: The compacted surface of DG helps suppress weed growth.

Uses and Applications of Decomposed Granite

Decomposed granite (DG) boasts a surprising variety of uses and applications in landscaping and beyond, thanks to its unique properties. Here's a breakdown of its popular applications:

Pathways and walkways: One of the most common uses of DG is creating attractive and functional walkways, garden paths, and even driveways. It provides a stable surface for foot traffic and light vehicles, while offering a natural look that complements gardens and landscapes.

Patios and courtyards: DG can be used to create beautiful and low-maintenance patios and courtyards. It compacts well to form a solid base for furniture and outdoor entertaining areas. Plus, the natural colors add a touch of rustic charm.

Drainage solutions: Due to its permeability, DG is ideal for drainage applications like French drains and swales. The spaces between the particles allow water to drain freely, preventing pooling and erosion.

Soil Amendment: Gardeners and landscapers often incorporate decomposed granite into soil mixes to improve drainage and enhance soil structure. The mineral-rich composition of DG provides essential nutrients for plant growth, promoting healthy vegetation.

Groundcover: DG can be used as a groundcover around trees, shrubs, and other plantings. It suppresses weeds effectively, reducing maintenance needs. The neutral tones of DG also create a clean and visually appealing backdrop for plants.

Fire resistant material: Decomposed granite is a fire-resistant material, making it a safe choice for areas around fireplaces and fire pits. It can help create a firebreak around your home, adding an extra layer of safety.

Other creative applications: Beyond these common uses, DG can be creatively incorporated into other landscaping features. For example, it can be used for:

Play areas: DG provides a safe and slightly cushioned surface for children's playgrounds.
Bocce ball courts: The compacted surface of DG is perfect for creating bocce ball courts.
Dog runs: DG offers a natural and low-dust surface for dog runs.

When choosing decomposed granite for your project, consider the variety of colors available to match your desired aesthetic. Remember, DG might require occasional topdressing to maintain its compacted state and prevent weed growth.

Weathering of Granite. Mount Evans, in Colorado
Photo: Ron Wolf

What are things to consider when using decomposed granite?

Why not to use decomposed granite?

Can wash away: Although permeable, heavy rain can cause some erosion of DG on slopes or inclines. Edging with stones or using a stabilizer can help mitigate this.

May need weed control: DG can be susceptible to weeds, so you may need to use weed control fabric or a pre-emergent herbicide.

Gets dusty: Decomposed granite can get dusty in dry climates, so regular watering may be necessary to suppress dust.

Not ideal for all driveways: While DG can handle foot traffic and light vehicles, it's not suitable for high-traffic driveways or areas that will experience heavy loads. Over time, heavy loads can cause the DG to break down and become uneven.

Not ideal for all slopes: While DG can be compacted for stability, it may not be suitable for steeper slopes. On inclines, loose particles might erode over time, especially during heavy rain. Edging and proper drainage techniques become crucial for slopes with DG.

Comfort: Decomposed granite can be uncomfortable to walk on barefoot due to its rough texture. This might be a consideration for areas around pools, patios, or play areas where bare feet are common.

Tracking: DG particles can easily track onto shoes and paws, potentially ending up indoors. This might be a concern if you have frequent foot traffic or pets that come inside. Using doormats and regularly cleaning can help minimize tracking.

Installation: How do you install decomposed granite?

Installing decomposed granite (DG) is a manageable DIY project if you have the right tools and follow the steps carefully. Here's a general breakdown of the process:

Preparation

Excavation: Mark and excavate the area for your DG project. Aim for a depth of 4-6 inches, allowing for the DG base and the desired finished DG layer. Consider calling a utility locating service before digging to avoid underground lines.

Base layer (optional): For high traffic areas like driveways or patios, a crushed rock base layer (1-2 inches thick) can be added for better stability. Tamp down the base layer firmly.

Define the edges: Install edging around the perimeter of your DG area. This can be plastic, steel, or concrete edging, depending on your preference and budget. Secure the edging firmly to ensure a clean border and prevent DG from spreading.

Weed barrier (optional) : Lay down a weed barrier fabric over the entire excavated area. This prevents weeds from sprouting through the DG. Make sure the fabric overlaps at the edges. While not always necessary, it can minimize weeding maintenance in the long run.

DG Installation

Spread DG: Spread the decomposed granite evenly over the prepared area. Use shovels or a wheelbarrow to distribute the DG. Aim for a layer 2-3 inches (5-8 cm) thick after compaction.

Raking and leveling: Use a rake to level the DG uniformly across the entire area. Ensure there are no dips or uneven spots.

Compaction: Compact the DG in stages. Lightly dampen the surface with water (like moist soil) to aid compaction. Use a hand tamper or plate compactor to compress the DG firmly. Reapply DG and compact again to achieve the desired level.

Finishing Touches

Topdressing: After initial compaction, you might need to add a thin layer (¼ inch) of fresh DG to address any unevenness caused by the compacting process. Gently rake and re-compact this top layer.

Edging maintenance: Push any DG that has accumulated against the edging back into place.

Watering (optional): A light watering can help settle the DG further, especially if you live in a dry climate. Avoid overwatering, as excessive moisture can wash away the fines and loosen the surface.

Additional tips for a successful DG installation:

Calculate the amount of DG needed: Before purchasing DG, factor in the area dimensions and desired DG depth to determine the required quantity.
Choose the right tools: Having a rake, tamper, edging materials, weed barrier, wheelbarrow (optional), plate compactor (optional), and water source will be helpful.
Work in sections: For larger areas, consider working on the project in sections to ensure proper leveling and compaction throughout.

With a little planning and effort, you can install decomposed granite yourself and create beautiful and functional walkways, patios, or other features in your outdoor space.

decomposed granite walkway

Decomposed Granite FAQ

How many types of decomposed granite are there?

There are two main types of decomposed granite based on their binding properties:

Natural or Loose DG: This is the basic decomposed granite with no additives or binders. It's affordable and offers good drainage, but can be susceptible to movement and require more maintenance.

Stabilized DG: This type of decomposed granite has binders or additives mixed in to create a more stable surface. Stabilized DG is less likely to wash away or move around, making it a good choice for high-traffic areas or areas with slopes.

What is the difference between crushed and decomposed granite?

Crushed and decomposed granite are both for landscaping, but differ in origin and use. Crushed granite is mechanically broken, resulting in sharp, angular pieces. Decomposed granite is naturally weathered into a rounded mix of gravel, sand, and fines. Crushed granite is good for drainage and areas needing a stable surface, while decomposed granite offers a natural look and works well for pathways and patios.

Is decomposed granite low maintenance?

Yes, decomposed granite is relatively low maintenance compared to other materials like concrete or asphalt. However, it may require periodic re-compacting, and weed control measures are often recommended.

Can decomposed granite be used in high-traffic areas?

Yes, decomposed granite can be used in high-traffic areas, but it may require more frequent maintenance and re-compacting to keep it stable.

Is decomposed granite expensive?

Decomposed granite is often more affordable than other paving materials like concrete or asphalt, making it a cost-effective option for landscaping and construction projects.

Conclusion

In conclusion, decomposed granite offers a unique combination of properties that make it a valuable material for various landscaping and construction applications. Its permeability, compactability, versatility, low maintenance requirements, and fire resistance make it a popular choice for walkways, patios, drainage solutions, groundcover, and firebreak applications.