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A trampoline can be a great source of exercise and entertainment, especially in warm weather when everyone wants a way to enjoy the outdoors. However, they are not without their downsides: some people view larger trampolines as an eyesore, while others worry about just how safe they can be.

Luckily, there is a popular solution: installing a sunken trampoline. This involves digging a hole for your trampoline to sink into, leaving the bouncy part at ground level and making the trampoline much safer and easier to use. This will also remove the need for an expensive safety net.

As you might expect, the work involved in creating a sunken trampoline involves careful planning and a good deal of physical labour. Because of this, it can be an excellent idea to hire a local landscape designer for the work. They will be able to prepare the area and excavate the ground as efficiently as possible, even if this means hiring a digger. A landscape designer can also help you to find a use for the unearthed soil, such as building a new bank or flower bed.

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Can I install a sunken trampoline?

Before you get started on installing your sunken trampoline, there are a few things for you to consider:

  • Space - Exactly how large is your garden? As well as room for your trampoline, you will also need to have a safety zone of around 1m all around the outside. You should also keep in mind how much usable garden space you will be left with once the project is completed.
  • Soil - Whether or not your project will be successful will unfortunately depend on the composition of your soil. If your soil has a high clay content or is easily waterlogged, the hole for your trampoline will regularly fill up with water. You will also need to make sure that the soil goes deep enough without reaching pipes or other utilities. Finally, you will need to install a support system for the trampoline. This will be particularly important for weak or sandy soil. You can save yourself a great deal of time here by having a landscape designer assess the area you have chosen.
  • Trampoline - Do you already own a trampoline for the project? If it is a small model, the amount of work involved in sinking it may not be worth the hassle. The best options will be large and round models with soft padding around the outside. You can even purchase a trampoline specifically designed for sinking, which will come with its own support system and vented padding.

How to install a sunken trampoline

As we mentioned previously, installing a sunken trampoline takes careful planning and a good deal of physical labour. It will not be enough to just dig a hole and plonk your trampoline inside - there are several safety concerns to address first, as well as other potential problems which we will get to later.

Start by measuring the size of your trampoline. If you have the model’s name and number, it should be simple to get this information online. You will need to know the radius, diameter, circumference and height to proceed.

Next, you will need to test the area that you have chosen for the installation. Do some digging (as described above) to see just how deep the soil goes. If there is sufficient space, leave your test hole for a few days to see if it fills up with water. Drainage is an issue that you should tackle early on - the last thing you want is to wake up one morning to find your trampoline floating in muddy water. A popular solution is to dig an additional trench at the bottom of the hole for your trampoline, then filling it with gravel or hardcore to create a soakaway.

The next step will be to mark the area for excavation. Drive a post into the centre of the area, then measure the radius in several directions, marking the outer points of the hole with spray paint. Connect all of the points in one large circle, then mark another 1m outside of the inner circle.

Now is the point that you have been looking forward to: digging the hole! Again, there is a lot of labour involved in this stage. You could treat it as an opportunity to get some exercise, though it will likely be more efficient for you to hire a landscape designer to organise the work. If necessary, they can even hire a digger on your behalf.

Before you get started on digging the hole, you should know exactly what you are going to do with the soil. One option is to hire a skip to take it away, though it can also be a good idea to simply store the soil in case the future property owners decide to fill in the hole. Alternatively, your landscape designer could provide you with ideas on how to repurpose the soil as a new garden feature, such as a bank or raised flower bed.

The hole for your trampoline will have two sections. The innermost section will be the deepest, while the outermost area will form a ledge for your trampoline to sit on. The inner section should be around 2ft less in diameter, though this will vary depending on the size of your trampoline. The outer section should also be reinforced with a retaining wall, especially if your soil has a high sand content. There are a number of in-ground trampolines on the market which come with their own supports.

Exactly how deep the innermost hole will need to be will depend on the size of your trampoline. Speaking roughly, the hole for a trampoline measuring 12-14ft in diameter should be around 3ft deep. The hole for an 8-10ft trampoline will only need around 2ft 6 inches. While this might sound tedious, it is crucial that you do not simply guess the depth. If necessary, speak to your landscape designer or contact the trampoline’s manufacturer.

Before installing the trampoline, you will need to deal with the issue of trapped air. Many trampolines come with vented pads which will let air pass in and out of the hole with ease. Failing this, invest in some flexible piping and install it around your trampoline at four-inch intervals.

Slowly lift your trampoline into the hole, then fill in any gaps with unearthed soil and pat it down with your spade. Next, attach the outer padding to the top of the trampoline. Be careful with the colour of this padding - you will want it to clash with your lawn as much as possible so that it is easy to spot.

Finally, you will need to make sure that the area around the trampoline is safe. Look for any objects such as stones, glass or pieces of broken brick and have them removed.