In-Ground Trampoline Solutions By Gary Courson Posted on September 30, 2017ContentsWhat to Do Before Beginning Your In-Ground Trampoline InstallationInstalling Your New In-Ground TrampolineHow Is an In-Ground Solution Safer Than an Above-Ground Trampoline?How to Maintain an In-Ground TrampolineWhat Is the Cost of an In-Ground Trampoline?One of the safest ways to enjoy the jumping fun of a trampoline is to install an in-ground solution. Some trampolines are designed to be placed in the ground, offering a framework that works with a hole you’ve already dug. Just slip in the frame, attach the jump mat, and you’re done. It’s almost as easy as planting a tree.What you may not realize is that almost any trampoline can become an in-ground trampoline with the right plan in place. As long as you have a solid foundation, move from the coils, rods, or springs to flex, and enough space for the installation, you can benefit from this safer jumping solution.What to Do Before Beginning Your In-Ground Trampoline InstallationCall 811 or your local utilities and have any lines, plumbing, or cables properly marked on your property before you begin to dig. In most jurisdictions, this is a mandatory step.Ensure your property is zoned for an in-ground trampoline. How a property is sloped for runoff can make an installation be against local building codes.Create a raised area in your yard if necessary to complete the installation. Water underneath the trampoline can impact the bounce effect and be a draw for insects, rodents, and other pests.Clear away any rocks and other landscaping or natural items that could impact the jumping experience.Installing Your New In-Ground TrampolineThe first thing you need to do is dig the hole for your trampoline. Make sure you reach the instructed depth from the trampoline manufacturer. For most trampolines, the hole must also be at least 1 foot wider than the circumference of the product for a successful installation. An 8-foot in-ground trampoline requires a 9-foot hole.Make sure your frame fits into the hole before going to the next step.Once the frame fits, you will need to have the trampoline frame be level. For a DIY installation, the easiest way to do this is to use concrete or cinder blocks that have a U-shaped groove in them. This will also give the frame firmer supports. Tamp the ground where it is not level until you receive a good bubble.Make sure you still have room for air flow as you level the frame.When the trampoline frame has been leveled, you’re ready to install the retaining wall if you are using one. Some install directly onto the frame of the trampoline. Others install in the hole that has been dug. Make sure the hole measurements will accommodate the extra space the retaining wall takes up if it is not affixed to the frame.Once the retaining wall is in place, you must ensure that drainage is encouraged. Run a perforated pipe underneath the surface and connect it to whatever drainage system you have –even if it is just a ditch. Adding pea gravel to the bottom of the pit is a good idea as well. Then place the frame into the retaining wall.Back-fill the hole to ensure that you have a solid fit. Your outside dirt should be level with the ground. You don’t want any gaps because this foundation helps the trampoline stay in place while in use.Then connect your springs, rods, or bungees to the frame and make sure the jump mat is nice and tight. Those are the basic steps to installing your new in-ground trampoline.How Is an In-Ground Solution Safer Than an Above-Ground Trampoline?From a mechanical standpoint, jumping on any trampoline offers the potential for injury. Even with a properly installed in-ground trampoline, a person may fall from up to 6 feet onto solid ground and that can create a serious injury.From a logistical standpoint, however, you’re going to be able to reduce some injury risks with this type of trampoline. Here is why.You have fewer contact points to hit. If the in-ground trampoline has a safety enclosure that is inside the springs or coils of the product, then there are fewer places where an injury may occur. The likelihood of bouncing over-top a 6-foot safety enclosure to hit the hard ground is also quite small.You have a lower yard profile. Imagine it is dark outside. You’re out in the backyard and your shin smacks into the trampoline frame. That never feels good! With an in-ground installation, your biggest worry would be not slipping on the jump mat if it happens to be wet.You eliminate the step-up. There’s no need to crawl upwards to jump on a trampoline with an in-ground solution. Just open the door, go through your enclosure, and start to have some jumping fun.The most common cause of injury for an in-ground trampoline, outside of jumping-related incidents, is limb entrapment between the ground and the frame of the trampoline. An in-ground trampoline must have air movement underneath the jump mat for it to create a proper bounce effect. Many installers use an outside retaining wall that leaves a small air gap between it and the trampoline to create this movement.To avoid this injury, consider an alternative method of air flow. You can pipe air into the pit, install a fan to create movement, or use your own creative idea. If space is limited, an easy way to create air while limiting a jumping injury is to have your installation pit be a little shallower than the height of the trampoline frame. It creates a tripping hazard but limits the other hazards.How to Maintain an In-Ground TrampolineWhen a trampoline has been sunk into the ground, there is a lot that could be going on underneath the jump mat that you just cannot see. Regular maintenance is one of the most difficult aspects of this type of trampoline. You need to put eyes on the frame, springs, and the underside of the jump mat on a regular basis to ensure the product is safe.One of the easiest ways to get around this issue is to create a drainage pipe from your installation pit that you can easily access. Perforated piping is your best option here. Run the pipe underneath the trampoline and into a drainage ditch. Then take a small, wired camera with a length that is long enough to navigate the pipe. You’ll need a light attachment. A live feed is the best option so you can inspect in real time, but any recording device is better than nothing.Do not rely on lifting the trampoline out of its installation area as a method of inspection.Most trampolines weight at least 100 pounds. Some of the largest trampolines can weigh over 500 pounds. You will need to leave yourself room to lift the trampoline out of its installation should something go wrong, but this is not the best way to inspect your trampoline regularly.An in-ground trampoline should be constructed with galvanized or powder-coated steel, so corrosion-resistance is built into the product. Inspect the frame at least once per month, but inspect the springs, coils, rods and jump mat before every use to lessen the risk of injury or product failure.If you are concerned about water filling the hole where the trampoline sits, consider purchasing a small pump that can quickly remove this issue. With proper drainage, however, unless there is flooding in your yard, the ground should absorb or funnel the water to its natural drainage area without an issue.It may also be a good idea to have the area sprayed for insects and inspected monthly for rodent activity.What Is the Cost of an In-Ground Trampoline?The cost of your new in-ground trampoline is dependent upon the type of trampoline you decide to purchase, the size of the trampoline, and if you are purchasing the retaining wall instead of building one on your own or going without one at all.You should always have a retaining wall in place with an in-ground trampoline for best results.Jump Power offers a 10×7.5-foot in-ground rectangular trampoline with their patented safety net cable wire enclosure system for under $375. It requires a 3-foot pit with drainage and has a 16-gauge, 1.75-inch galvanized steel frame. The maximum weight limit on this product is just 220 pounds, however, so it is designed for single-person use.A pre-engineered in-ground trampoline system which includes a retaining wall begins at $1,700 for most manufacturers. This type of system is delivered curbside, but freight arrangements may make it possible for a backyard delivery. These in-ground systems are nice because the jump mat is designed to assist with the airflow, but homeowners must ensure that the product meets coding and any HOA standards before completing their purchase.Plum manufactures an in-ground trampoline system that offers a round 8-foot frame that blends well with most landscaping plans. It utilizes PVC springs, a UV-treated jump mat, and a 2mm gauge top-rail to provide increased protection against the weather. The retaining wall is built into the product as well, which makes it one of the easiest installation options available right now.An in-ground trampoline may not be the right investment for everyone, but it is a fun way to spruce up the backyard and have some good old-fashioned fun. Consider all your options, including above-ground trampolines, to make sure you’re making the best possible purchase.