The best material for under artificial grass is a mixture of rock or gravel smaller than half an inch mixed with some fines such as crushed granite or sand. The layer directly beneath the grass is important because it needs to provide a solid foundation while also providing adequate water drainage. Ensuring that the sub base is done properly will provide many years of hassle free enjoyment of your synthetic lawn.
In addition to choosing the right material it's important to prepare it properly by levelling and compacting it for optimal stability, drainage and aesthetics. In addition to the best gravel for under artificial grass, we are also going to take a look at the process of removing existing materials, preparing the sub layer and some other options to consider that will ensure you don't have any issues with settling, shifting, water pooling and of course weeds.
Yes, a gravel mixture under the grass is necessary unless you are installing artificial grass on concrete or something with a solid foundation like a deck. The process of removing the existing organics; natural grass, soil, etc and laying the grass on top of packed gravel will ensure you can enjoy your grass for many years. The sub-base aggregates most commonly used are a mixture of 3/8 inch chips, either granite or limestone blended with sand.
Things that you want to avoid under synthetic lawns include anything living or materials that don't pack into a solid form or drain very well. This includes vegetation like natural grass, weeds or tree roots as well as basic topsoil that doesn't pack, hold its form or provide adequate drainage. The ultimate goal is to clean out all organics and replace with at least 3 to 5 inches of a packed gravel and fines mixture.
A common mistake we see are sub layers that consist of only gravel or small stones such as pea gravel or small rock. This type of material will provide adequate drainage but because it's rounded and lacks a fine such as sand, and it won't pack into a solid foundation. If the area is going to be enjoyed by dogs or as a place to pee or poop it's even more important to get the foundation right to provide drainage and reduce odours from urine.
In order to lay artificial grass on gravel there are a few important steps to consider to get the most out of your new lawn. The amount of gravel crush required depends on the depth of the crush layer with the goal of building the base to a level about 1/2 inch below the desired top grade with the installed grass. The artificial grass installation process has many steps but we'll cover the important base prep procedure in detail below.
The area where you are replacing with your new synthetic lawn will likely need some prep work done and the first step is to remove the old materials to make way for the crush gravel. This could include existing natural grass, dirt, weeds, sand or rock. A general rule is to remove these materials down to a stable layer with natural drainage and can range anywhere from 4 to 8 inches.
Once the area is cleaned out you should access all the edge border materials where your grass will be located. A good edge or border material includes solid materials like concrete driveways or walkway and even wood along the edge of a fence. We recommend creating a sturdy border by installing an edger like a plastic bender board, metal edger or treated wood wherever you don't have an existing solid edge.
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With the area cleared of organics and the edger installed where needed, it's time to fill with a quality gravel crush mixture. The calculation for the amount of gravel mixture required is shown below and will just need to be multiplied depending on the total square feet of the area that you need to build up your base layer.
A typical 500 square foot section of artificial grass excavated to a depth of 6 inches will require 10 cubic yards of crushed gravel mixture. Keep in mind that an average cubic yard of crush weights about 2,200 pounds. This amount of crushed gravel is typically transported by dump truck and can either be placed in the project area directly, if you're fortunate, or needs to be transported via wheelbarrow or cart to a remote area like a backyard.
The next step is to level the gravel mixture to form the base. This is where a keen eye, and a good landscape rake, comes in handy. If the overall sub layer has a natural slope you can aim for a tabletop finish but if it's relatively flat or is a large area we recommend creating a very slight crest or dome to encourage drainage. Keep in mind that it doesn't need to be perfectly flat as it often looks more natural to have subtle variances.
Packing the sub layer creates a solid foundation that will be the backbone of the grass and will ensure it stands up to added weight while still being permeable. A vibratory plate compactor is recommended as it will lock the gravel rock and fines into a solid layer. The process of getting the gravel damp, running the packer over the area and repeating will ensure a very solid base for the grass. This process also ensures that you have a solid backing for the fastening nails to grab and hold the grass in place.
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This list of frequently asked questions about artificial grass gravel is comprised of inquiries from home and business owners like you. If there is a question we haven't covered contact us with your question and we will answer it as soon as possible and add it to our list.
Where can I purchase gravel crusher chips?
A 3/8" or smaller jagged gravel crusher chip mixture is available at most local aggregate landscape supply stores and will often provide delivery for an additional fee.
How much does a cubic yard of gravel weigh?
A typical cubic yard of gravel aggregates weighs roughly 2,200 lbs or 1,000 kg.
What's the best way to level the gravel mixture sub layer before laying artificial grass?
Typically a landscape rake is used to level large areas of gravel crush.
How do I compact the gravel sub layer that artificial grass will lay on?
The best way to compact and level the gravel mixture after its been raked is to use a vibratory plate compactor that can be rented from most tool rental shops by the hour or by the day.
What's the best sub layer beneath artificial grass if I have dog?
A layer of 3/8 inch gravel crusher chips mixed with sand packed to a depth of at least 3 inches is the best sub layer for artificial grass grass.
How do I fix lumpy artificial grass?
If you have lumps in your artificial grass the easiest remedy is to use a rubber mallet for small areas or a landscape roller barrel for large areas.
Is pea gravel good for an artificial grass sub layer?
Pea gravel is not a good sub layer for artificial grass as it won't pack or hold its form over time.
Is a weed barrier fabric required on top of the gravel base and under artificial grass?
A weed barrier fabric is not necessary if the sub base layer is at least 3 to 4 inches thick and packed adequately. If you live in an area prone to persistent weeds or can't install a sub layer to the recommended specifications a weed barrier is a budget friendly way to prevent any weeds from ever growing through the grass backing.
Please use all appropriate and proper safety precautions when attempting projects on this website. All projects are attempted at the reader's own risk.
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Duralawn® artificial grass installations, products and service in Kelowna, Vernon, Penticton, etc since 2018.