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The pitfalls of pit construction: the rock solid truth.

retrofitIn our 39 years in the gymnastics biz, we’ve heard tell of many things pit. Among them lurk more than a few horror stories, entailing the woes, befallen those who seek to construct a gymnastics practice pit without factoring in the lay of the land, the mechanics of the bed and all the necessities for strong and properly poured concrete walls.

We’d like to share a few of those tales of the crypt, as cautionary tales of sorts on what… Not to Do.

First and foremost: don’t get your buddy to dig out and simply pour concrete into your would be pit. It may seem tempting and affordable. For the cost of a 24 pack, some laughs and a few pizzas, you, too, could have a brand, spankin’ new pit, but no. Really, no. Don’t do it.

Gymnastics pits are much, much more than a simple hole walled in concrete. To really build something workable — that will last! — it’s got to be done correctly.

For that to happen, it’s got to be done by a professional. Your brother-in-law bowls with a guy who does driveways; your cousin runs a cement truck; one of your old college teammates has a backhoe. It sounds too good to be true and trust our nigh on 40 years of experience: it is.

Your gymnastics pit will need to withstand the dynamic and changing forces of nature. One of natures greatest forces is water. Water cuts valleys into mountains and unless you want water to turn your gymnastics pit into an indoor swimming pool, you need to work with someone who understands gradients, backfilling dirt, run-off and the ways of concrete — of which cement is only a part. Your best bet, of course, is to contract out with someone who has done successful gym pits before. Short of that, work with someone who builds sub-basements or parking garages that are below ground level. Your gymnastics pit absolutely must be waterproof!

And, that means waterproofed from the backside where the dirt meets the concrete.

Build your gym down hill where water will naturally flow when it rains and you and your coaches will end up crying.

Are you building your gym pit in an area with a high water table? Are you on one of the coasts? Coastal areas have water in the ground all the time. Make sure you and your contractor understand the lay of the land. Make sure your pit is properly landscaped and equipped with a sump pump to take away any water that’s likely to accumulate and direct it away from your pit.

Once upon a time, a contractor built an L-shaped pit without attention to grading. Water didn’t get diverted to the sump pump; water ended up collecting in the short leg of the L.

One well-meaning contractor put drain pipes in the bottom of the pit thinking the water would drain out. Turns out the water drained in. That had to be fixed. As you can imagine, it wasn’t free and it didn’t get fixed in a day.

Get someone who knows and follows local building codes. We’ve seen pits where the walls were poured too thin and those walls have cracked or collapsed. What may seem like frugal cost cutting will end up costing you more time, money, labor, supplies, equipment and gym downtime further down the line.

Talk to your professional contractor about concrete psi. Psi refers to the strength of your concrete and its abilities to withstand force per square inch. Skimp here and your concrete will crack or your walls will collapse when bolting the trampoline bed in or they will give way with the repetition of use.

You also need more than just concrete: concrete must contain rebar. Rebar or wire mesh is what holds the concrete in during the curing process and helps it withstand the forces of gravity and repeated use with a spring trampoline bed. No rebar means cracks, possible collapse and sadness.

This may sound kinda picky and precious, but for your pit to perform all elements of it: the hole, the walls, the bed; the pads must work with the precision fittings of a Swiss watch, that is to say like a well-oiled, geared and cogged machine.

straightwallsThat means… those walls need to be straight. Wonky walls won’t accommodate a bed held together by a metal frame and springs. There’s no room for compromise on a bed built with a metal frame. Dimensions must be exact. They need to be what you tell us they will be because we will be building your bed and frame padding to those specifications.

We’ve had people tell us the walls of their gymnastics pit are “a little off”.

“Hey Mike, we had a small problem. Our walls are three inches off… Can we add concrete?” Sorry, but no. You can’t. If the hole isn’t the right size the bed won’t fit, hook up or it will be too loose.

“Gee, Mike, can we bend the frame? Some spots on the walls got a little bowed.” Nope! Our advise was to chisel out the extra curve and boy was that a lot of chiseling. Save yourself the frustration, the headache and expense. This is why you get someone who knows what they’re doing and guarantees their work.

“The backfill dirt fell in and pushed the forms, the forms moved during the curation process,.” Ouch. That’s bad. Again, the bed is built to fit a certain sized hole and only that sized hole. We once had a customer who’s pit was six inches off! Half a foot! It’s like trying to shove a size 12 human foot into a size 6 shoe. You can’t expect that to go well.

measurements and bedsagFor a sag bed pit system to hook up and work, maximum wiggle room is half an inch.

The same thing goes for trying to put a size 6 human foot into a 12 inch shoe. Trampolines beds are a bit like Goldie Locks. The size of the bed in relation to the size of the hole has got to be just right!

And, so you know, your walls have to be vertical! Frame. Hole.

Okay, we’re all in agreement on waterproofing, correct dimensions and solid concrete with rebar… Let’s talk shape. Which brings us to another really important point: communication.

We are going to do what you ask us to do. We build to your specs. That said, you have to build to ours. Once the plans are drawn up, everyone has to hold up their end of the bargain.

For example, we worked with a customer who wanted a T-shaped bed with the accompanying pads. We sent them everything fit to spec. The thing was, in the process of building on their end, they flipped everything backwards. They didn’t bother to tell us that, so the bed and the pads we sent them didn’t fit the hole. The tumble trench was not in the right spot. The bed was bigger than originally specified and they had to change from 8 to 10 inch springs. In short, everything had to be redone.

tumbletrackrodfloorAlso, please don’t spontaneously lengthen or shorten a leg. We make pads and pedestals to fit exact dimensions. If you first tell us that the leg will be 8 feet, that’s what we do. If it ends up 9 feet… well, Houston, we have a problem. Given that everything works as a synchronized unit, the parts will have to be re-synched.

That’s why communication is key! This is always true in matters of geometry, but it’s especially, extra true with cherries on top, when you’re not building a square pit, ie. the pit is T or L shaped.

While we’re on the subject… an hourglass pit may look and sound cool, but it’s not a good idea when you’re trying to put a trampoline, spring bed with custom fitting pit pads into it. It makes for some weird angles that aren’t conducive to the mechanics of a spring bed and its symbiosis with its tailor made pit pads. Going in and out and around gets complicated when you get down to brass tacks and moving springs covered by pads. Fitting this is a nightmare. Dare to dream big, just make sure it’s all in right angles!

We would be remiss if we didn’t mention depth when talking dimension. Pit depth depends on size. The larger the pit, the deeper it must be to accommodate bed sag. Most pits are 6 feet deep because they’re 20ft x 20 ft or less. Any bigger than that, and you’ll need to add a bit more depth for the resulting increase in bed sag due to increase in cube volume and weight.

Okay, you’ve got the proper depth, the walls are straight, the pit is oriented just like in the drawing… Oops! There’s that column right in the middle of the pit pads! That wasn’t on the drawing! Oh no! The pit is 12 inches away from the wall, but what about the footers? If you’ve read this far, you get where we’re going with this… Communicate. Design. Communicate. Execute.

Honorable Mention:

Make sure you’ve invested in a quality sump pump. This week we got some heartbreaking news. One of our customers had to rebuild from the ground up because their sump pump caught fire.

If you’re putting a pit into an existing gym, curtain it off from floor to ceiling while doing the work. We had a customer who let her contractor come in on the weekend to dig the pit into her existing concrete slab foundation. Monday morning, she had a gym full of gritty concrete dust. Not fine and silky, like chalk, but sandy and dirty and not fun to walk or tumble on with bare skin.

Customer wanted a resi pit. Customer dug a hole and boarded up the sides with plywood. Customer ended up with a big ol’ moldy mess where water had seeped through the dirt to the wood. Um, no.

Customer wanted a trampoline pit. Customer dug a hole in the dirt and stuck a freestanding trampoline in it. No concrete. No nothin’. Really? Seriously?

So there you have it, words to the wise from a company with decades of experience.

You don’t have to go it alone. By GMR is here to work with you. We will help you plan, design and fit our dynamic sag bed pit system creating your perfect pit. We’re here to answer your questions and help you avoid the pitfalls of pit construction and installation. When By GMR designs your gym and/or pit, we provide contractor ready blueprints that lay all the dimensions out.

We do, however, need a couple of things from you. We need you to find the right professional contractor and work together with them to construct a pit that will accommodate the bed and pit pads, we will make just for you. We need you to talk to us and ensure that your contractor follows through on your specifications, so your pit sits ready for your new sag bed pit system to nestle right in.


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