Everyone loves sunken trampolines (also known as in-ground, ground level or even pit trampolines) for many good reasons. There has always however been a resistance to installing a sunken trampoline due to issues such as cost, drainage, soil removal and so on.
It is however not as difficult as you may think to install a sunken trampoline, and I'm going to explain all the options you have and make it easy for you to obtain a perfect in-ground trampoline solution.
Here's a recap on some of the reasons why in-ground trampolines are becoming so popular:
This is your first consideration. You'll need to make sure you don't have a high water table or you're prone to flooding. If in any doubt, dig a trial hole (about 3ft deep) in the area where you want to sink your trampoline and leave for 24 hours to see if the hole fills up with water.
You will need at least 2 metres around the trampoline as a safety area to jump off. You should ensure this area is a suitable “soft” surface such as grass or rubber surfacing. Make sure there are no hazards such as brick edges or concrete posts in this area which could cause injury.
Finally try and ensure there are no utility services such as gas or water pipes in the area where you're going to dig. This can be an expensive oversight!
The first thing you'll need to consider is what size and shape trampoline you want.
What works best in the space you have? Round or rectangular. Do you have an existing trampoline you want digging in?
If you have an existing trampoline you want digging in then you will need to use a retaining wall to stop the earth falling in under the trampoline.
Size? You should also look to buy as large a trampoline as possible - kids grow up quickly and of course lots of friends will use the trampoline. More space means more room to play, hang out and make games.
The cost of upgrading to a good specification trampoline is not that much in relation to the overall cost of your project. Chosing a higher quality trampoline means it will last longer in the ground, be safer, and always have spare parts available to you.
Using a traditional trampoline and full-height retaining wall will mean you'll have to excavate a lot of soil and the cost of the retaining wall is expensive.
A better option is to purchase a purpose-built in-ground trampoline such as the North Inground Trampoline Kit.
The design of this solution means less soil disposal and the cost of the trampoline and retaining wall is also reduced.
Firstly you'll need to determine the size and depth of the hole you want to dig. If you're using a full height wall and say a 12ft round trampoline, you need to dig a 14ft circumference hole to a depth of about 3ft. Once the trampoline and wall are in place, you then fill in on the outside and inside of the wall.
If you are using a North Inground Trampoline Kit, then there is less soil to dig out. The profile of the hole is pictured on the left here.
You have the option to either hand-dig the hole or use a mini-digger. On a smaller trampoline say a 10ft, provided your soil is not too hard, then it's fairly straightforward to dig by hand. It will take two people a full day and make a great work-out!
If however you have a larger hole to dig, say 14ft, then a mini-digger will greatly assist digging out most of the soil, whilst you can finish by hand.
Whether hand-digging or using a mini-digger you will still have the issue of soil disposal. You will need to hire a skip or better still use a grab lorry to remove the soil.
Many people think that they can lose their dug-out soil in their gardens e.g. in flower beds, in borders, behind sheds. Soil expands as much as 3 times when taken out of the ground and there's a surprising amount of earth that comes out of a trampoline hole.
Whether you need drainage will depend of the type of soil you have. If you have sandy soil, you probably won't require any further drainage. If however you have non-porous soil which has a high clay content, then it's wise to at least put in a soak-away or similar at the bottom of the hole.
In more extreme cases a drainage channel may have to be dug out to a lower lying area in your garden.
Putting a cover on the trampoline will also help prevent excess water getting into your hole.
Historically, this was a real problem for in-ground trampolines. The quality of the bounce would be affected if there's nowhere for the trapped air to escape as you bounce on the trampoline. This is especially true for older or heavier children.
You'll also experience the high irritating 'pad slap' noise as the trapped air pushes up the pads and they slap down on the jump mat.
North Trampoline use vented safety pads AND vented jump mat, this is our unique Double-Vented system, which allows airflow through all areas of the trampoline, removing the air resistance and increasing the bounce, this means you can bounce easier for longer periods of time and it’s quiet too!
Installing a sunken trampoline is great fun and a very fulfilling. Your children will get hours of endless fun on UK's no 1 piece of children's play equipment.
