DIY: The Ninja Warrior Gym
Several months ago, my wife and I came to the sobering conclusion that we would likely be finding ourselves at home indefinitely, and with two kids (7 and 8…almost 9…) sitting around the house with activities all cancelled, it seemed like we needed a solution for exercise long-term and something to do short-term.
So, we did what any rational parent would do: We started designing what would soon be known as the Pandemic Warrior Gymnastics Facility!
The Design
I am a software engineer, not a structural engineer, so I wanted to leverage expertise from others in the process for designing the gym, particularly around the structural aspects.
I started with a foundation from ninjawarriorblueprints.com, which had not only some wonderful architectural drawings, but also specific parts lists and great instructions for how they thought through their build. They are awesome. Would recommend.
At the same time, I had a growing library of images, posts, and videos I had watched online with different features I wanted to incorporate, many of which were not in these blueprints.
So at a high level, we would keep their basic frame concept of 4x4 posts wrapped with 2x8s strung about 8' off the ground, but I would be making a variety of changes…mostly involving adding a copious amount of galvanized pipe.
My son, Arjun, wanted to pack in as many tricky Ninja Warrior features as possible, including a Salmon Ladder, Devil Steps, and Cliffhangers! My daughter, Arya, wanted more gymnastics features, such as uneven bars and gymnastics rings. On my end, I wanted it to be safe, I wanted the thing to be useful for them through high school, and I needed to adjust for the space I had available in the backyard (most of which would be going to the kids!).
I don’t have experience with CAD software, so the designs were mostly managed in Figma as we laid out the fine-grained details.
The Build
The kids have grown up around my various DIY projects and have helped around the edges. This time, I would have them driving the build, and we could incorporate some education along the way.
To begin with, laying out the locations of the posts became a fun lesson in trigonometry. The idea here is that you can ensure you have a proper 90° angle if you measure the hypotenuse down to the 1/8", and as the diagram above shows, we used some long distance diagonals to validate our measurements, as well. Ironically, the extreme accuracy of these early measurements turned out to be a bit silly, given the “accuracy” of the two-man auger we rented to dig the post holes.
To our left you can see Arjun and a neighborhood friend managing quality control as we man-handled this enormous auger. That engine belongs on a motorboat—if not a helicopter — rather than at the hands of two amateur builders. But we made it work. Thanks, Dave, for the assist!
Several hours of sweat equity, and we had 10 post holes for 4x4s at 12" wide and somewhere around two feet deep depending on clay deposits. This gave us room for two 50 lb. bags of concrete per post, which means the gym is anchored by 1,000 lb. of concrete. Job done.
Before the lumber showed up, though, we had a blast with the kids doing mini DIY projects for the smaller components, particularly the elements for the “Hanging Garden.”
Here is Arya using a drill guide to drill holes in PVC pipe. The drill guide ensures that the hole is dead center, but it also prevents slippage, adding a nice safety feature when kids are involved. We clamp the drill guide and ensure it’s secure before picking up the drill. We smile for the camera periodically, but it’s all business when the drilling is happening.
And here is Arjun with our ghetto fabulous jig we built to drill through lacrosse balls for the globes. We hollowed out a bit of spare 4x4 for the ball to sit in, and the clamp prevents it from spinning wildly during drilling. The drill guide is clamped in place dead center on the ball. The kids knocked out 8 of these in a matter of minutes, and then screwed 8" zinc eye bolts into a washer/nut combo to complete the component.
Throughout the build, we continually re-emphasized basic “construction site” safety, and managed to get them comfortable using the power drill, the compound mitre (chop saw), and hammers and awls, etc., quite safely. Communication was solid, focus was solid, and we had no injuries to report.
For the Salmon Ladder rungs, we were able to dial in the compound mitre to a 35° angle and set a jig using a clamp and spare wood. Arya and Arjun both took turns with this one, with me keeping a close eye on safety measures and technique.
We really hit our stride on the fourth afternoon. One kiddo drilling holes, and the other sanding the surface down to smooth.
On the left, Arya is cranking a ratchet to secure carriage bolts holding up the 2x8s. Awesome.
To be honest, it’s really not an exaggeration to say these two kiddos built most of the gym. I sure hope they remember this forever, because their effort was kind of epic!
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All told, it was about a week of work spread over 2–3 weeks, with most of the light construction taking place in 30–60 minute blocks before we broke ground (literally) on the post holes. Most of the heavy construction took place over a single weekend: holes and concrete on Saturday, 2x8 framing on Sunday. The rest was knocked out in 1–2 hour blocks the week that followed.
The Course
Alright, let’s take a tour, shall we? Now that the work is done, what are we working with?
The Salmon Ladder
A perennial American Ninja Warrior favorite, the Salmon Ladder features two vertical posts with rungs hanging out at 35°. We have a 1" EMT conduit pipe for the kids and a proper galvanized steel pipe to hold my weight as you make your way up the ladder.
Each jump is a pull-up combined with a little salmon-like shimmy as you move the pipe up to the next set of rungs. The ladder is 12' high, so it should be challenging us all for years to come. Note: The rungs are Redwood, which is long-term stable in terms of the elements, but it’s a soft wood, so we found that slamming it with steel pipes led to chipping, so I reinforced the rungs and post with tie plates.
The Devil Steps
Also a Ninja Warrior favorite, the Devil Steps feature 2x6 cross members moving up at a 45° incline. The steps are fastened with TimberLok lags and supported underneath with 18 gauge steel angles.
The steps serve to help stabilize the Salmon Ladder, the provide a path down from the top of the Salmon Ladder (for when that time comes!), and they provide a handy walkway from the Rock Wall across to the Pegboard. Since the kids treat the entire gym as an enormous playground structure, the steps are generally quite useful.
The Hanging Gardens
The Hanging Gardens are where we put all the PVC pistons and the lacrosse ball globes. The varying shapes are great for grip strength, and since we attached all the elements with carabiners, we can rearrange the elements over time to create varying courses. Larger, oblong PVC constructs add visual interest (and unlock the upside-down badges!).
We also built an Unstable Bridge, a Ninja obstacle with a flat board suspended from above. To navigate this obstacle you have to balance yourself while shimmying along the board as it rocks from side to side. Tricky.
The Rock Wall
We ran a handful of standard rock wall climbing holds along one side of the apparatus and up the side of the Salmon Ladder. This is easily the most approachable obstacle on the gym for little ones.
We have been spotting my four-year-old niece as she climbs that area. There has been some talk about adding a more challenging bouldering component over by the garage, but for now that remains a future project.
The Pegboard
On the opposite side of the Rock Wall features we have something quite a bit more difficult: The Pegboard! The pegs are 1–1/8" wooden dowels cut to 8" long, and we drilled 1–1/8" hole to match alongside the 2x8 and up the side of the Salmon Ladder.
The hard part about the Pegboard is that you really need to be able to execute a one-armed pull-up to reach a peg up to the next hole. In a few years, I suspect the kids will be showing off on the Pegboard, but for today this one remains fairly dormant.
The Incline Monkey Bars
A towering 12 ft. off the ground, the Incline Monkey Bars are a great upper body workout. To my delight, the kids instantly discovered that they could take a break if their arms got tired by stepping on the 2x8 on the outer edge. This turned the whole tall area into a giant play structure with much less for parents to worry about.
The monkey bar pipes are 3/4" galvanized steel (outer diameter of 1–1/16 inches) affixed firmly with galvanized iron flanges, and I ran the pipe an additional foot on the other side, complete with iron caps, to support a bonus challenge: Rings on Pipes!
It will be a couple weeks yet before Arjun can navigate the outside with gymnastics rings.
The Uneven Bars
Arya’s primary request for this gym was to have uneven bars to practice proper gymnastics at home. How could I say no?! These uneven bars are set at the high school specification. The first bar is 5' off the ground, and the second bar is 8' off the ground. They are separated horizontally by 5.5', which means both kids are already comfortable leaping from the lower bar to the higher bar.
In reality, gymnastics bars are fiberglass core wrapped in wood. They have quite a bit of give as gymnasts swing around them. In our case, though, we stuck with galvanized steel pipes, which are more rigid but should be more stable and long-living for the home environment. While our monkey bars are 3/4" pipe, the uneven bars are 1" schedule 40 pipe, which has an outer diameter of 1.31". The Olympics spec is 4 cm. (1.57"), but 1.31" felt better for a 7 year old’s hands, particularly since the steel bar has less give. 1–1/4" schedule 40 would have had us at 1.66", which is too much. This is where Arya spends 80% of her time, so it seems we got it right!
The Rope and Rings
Of course, we have a proper climbing rope and a set of gymnastics rings hanging from the incline monkey bars. These have provided endless opportunities for random games, assists onto the uneven bars, pseudo-workouts, and more.
In the future, Arjun might get a bit more serious about doing actual gymnastics activities using the rings, but in the meantime, I am working on my muscle-ups, and everyone is having fun climbing the rope.
Cliffhangers
Last but not least, we have a circuit of cliffhangers made from 1x2 furring strips. The section visible below has the 2" edge protruding from the board, giving you ample space for finger grip.
On the opposing side of the circuit, though, the furring strips run flush, giving you only 1" to grasp.
The Pandemic Warrior Sign
To wind up the process, our friend and neighbor Bobby Brenman offered to let us use his Glow Forge Laser Printer to etch a sign out of remaining Redwood 2x8. I designed the sign using Figma, and we went through a couple early iterations before burning the final copy.
I think it really cements the idea of how special the gym is to have such a unique and beautiful sign there, and it also serves to make clear what our rules are! Because we’re still in a pandemic, any time a neighbor is over using the gym with us, masks, shoes, and even gloves are required so we don’t have to go through and sanitize.
Next Steps: Added Safety Precautions
It is tough these days to strike the right balance around safety. I know when I was a kid, I found myself on park structures that had me more than 12 ft. off the ground. At the same time, we want to feel comfortable that the kids aren’t going to get seriously injured using this thing.
As a starting point, we have told the kids that parental supervision is required at all times. The exceptions here are all the low-impact stuff near the ground, like the Hanging Gardens. But if you’re going up in the air, parents need to be around.
Structurally, though:
- We are laying down 3/4" thick recycled rubber mulch mats. This provides a bit of cushioning and blocks weeds while allowing rain to pass through.
- On top of this, we have 2" thick gymnastics mats, which are movable and can be folded to double or quadruple up to 8" when crazy stuff is being attempted on the uneven bars (for example!).
- We are wrapping wrapped sixhighly-trafficked 4x4 posts in column pads (like the kind you used to see in gym class!)
- Finally, we bought two proper bouldering crash mats to help for scenarios where the kids are high up in the air, like the Salmon Ladder in years to come. This crash mat provides that extra bit of cushioning in the event of a fall from higher up.
All told, it was a fun project to design and fun project to build, and now we have a gym in the backyard the kids can use for the next ten years!
