I think a sunken trampoline has to be my favourite family garden feature. It's a simple enough idea but solves so many headaches. It's safer, less intrusive and popular with everyone.
I have sunken a couple myself. Well, to be more accurate, I've sunken the same one twice (note to self - decide where to put the thing and don't change your mind after 12 months). And I have also designed several gardens with sunken trampolines, so I now consider myself, if not an expert, certainly au fait with the ups and downs (no pun intended).
So what do you do...?
- First, measure up - I would say buy a relatively large trampoline (ours is 14') but make sure that it won't dominate the garden. Also, when measuring up, remember to leave at least another 50cm all round for the doughnut (don't worry, I'll come to that later)
- Purchase your trampoline - these are easy enough to buy online and I personally don't think there's a massive difference between the brands. What is worth looking at is shape and weight limits. You might think the trampoline will be used by the kids, but you'd be wrong - adults are at least as likely to want a bounce (and in my experience, more likely to injure themselves, but that's another story). So, get one that will take up to 20 stone.
- Choose the shape and colour - mine's round, because it suits my garden shape, but I've also used rectangular ones to fit into clients' gardens with a more formal layout. Also - don't forget to order green padding at the side (khaki if they offer it) as it's less jarring than bright blue
- Mark out the size of the trampoline - I have an old screwdriver I place through the end of my tape measure - stick this in the ground, hold a can of spraymark, and run round in a circle, spraying (just watch your shoes). If it's a rectangle, try to use a builders square to make sure you are accurate, or simply place your trampoline upside down in the ground and mark round it.
- Get digging - OK, you can cheat and get in a man with a digger, but this is likely to cost around £300 so if you're on a budget or need the exercise, do it yourself.
- Topsoil good, subsoil bad - Remember, the first foot or so is likely to be topsoil and should be kept to one side. Below this is subsoil - and if you can, I would suggest this is taken off site, or buried somewhere below topsoil. You can see the difference quite easily as you dig down. If you’re digging it yourself, allow a weekend and consider getting in some help as it's pretty hard work, especially when you get further down and the soil's more compacted.
- Drainage - If you've got a high water table or bad drainage, I would suggest you make a mini sump in the central area by digging down an extra foot and filling with rubble or pea shingle.
- What depth? - I've seen advice which says; leave the trampoline sitting 2 inches above the ground to allow air to escape. Personally, I don't do this. I've not found the air flow an issue unless it's been raining which covers the micro-holes in the trampoline surface and stops effective bouncing, but this is rare. Also, if you sink it flush to the ground, it stops things falling under the trampoline, negates a trip hazard and makes it easier to mow around.
- Use top soil to form a doughnut - I put a foot high, double sloped and flat-topped edge round the area which disguises the trampoline from a distance. The children also love running down this onto the trampoline
- Turf the area - this helps make a neat finish and you can fold it over at the edges if you need to fill in any holes
And that's it, except to say, sunken trampolines might be safer, but not so safe that you shouldn't supervise very carefully. However, they do make it easier for all ages to enjoy - my son was happily bottom-bouncing on the trampoline before he could walk and even Eric the cat enjoys a stroll over the surface to put a spring in his step.