*Ultimate* Interactive Gym & Dojo

About: 3D Designer, Fixer, Kickboxer and maker of the weird & wonderful.


I’ve been doing Martial Arts (kickboxing/kungfu/Thaiboxing) for 20 years and when me and the wife finally decided to buy a house together, apart from having 3 rooms, a big garden space was at the top of the list to build my mancave/Gym/Dojo.I want to start by saying im not a builder... and couldnt afford to get a builder to do this so I used my skills of research and creativity. Some of my methods are unortherdox but work. Better materials are avaiable but I was on a budget. In total it cost me about £3500 for a building 36 square meters big.

Step 1: Demolish & Clear

So...first off I cleared out the old space... this was brutal.. cut down trees, thorn bushes, crazy paving...etc. So I could calculate the size/shape (trapezoid).

Step 2: Planning

The most important thing I had considered was the punching bags being able to withstand the full power of any blow. Sounds simple? NOPE!!! I looked at brick... but every gym I have been to has had a bag frame pulled out the wall by a kick at some point. I thought of freestand machines..!!! Yes for kids punching.... but grown man kicks tend to bend the metal frames. Wooden frame built into the wall ?? Maybe.. but I wanted cheapest and strongest. The answer was scaffolding but il come onto that later.Another huge factor to consider was floor space... I didnt want a beam/pillar in the middle holding up the roof as this would hinder sparring with my pals. So I sat on the internet for a few days until I found a solution called a wooden I-Joist.Knowing a 6 metre wide flat roof was possible I continued designing. 3D Designs I put together to check spacing between toys :) ...

Step 3: Dig the Base

I dug about 2 foot down, and removed all of the soil. The old fashioned way with a spade and wheelbarrow.

Step 4: Dig the Post Holes

Dig the post holesTo make my build proper solid I dug 1 meter holes (ontop of the 2 foot already dug) for the main building posts and punch bag frame poles (2nd hand scaffolding bought on ebay £35). In total 6 holes for punch bags... and 7 holes for building posts.

Step 5: Electrics & Power

I dug a straight line (45cm deep) from the side of my house (where my house electrics is) though my garden and to the inside of my gym (where the mini consumer unit will go). I placed a 2.5mm 3 core armoured cable in the trench and then put 2cm worth of builders sand on top. Drop 10 cm worth of soil on top of the sand and then for extra measure I placed on top of that yellow electrical warning tape (bought from ebay). On the off chance someone digs down in my garden they will hit the tape first and not our power cable.

Step 6: Hardcore for Base

Put bricks and slaps of concrete in the base before smashing them up. This creates whats known as 'hardcore' to strenghten the cement base. I used the concrete panels from an old garage we had knocked down. But you can use bricks/ broken paving slabs. I made a perimeter using the panels to prevent soil dropping from the sides and to create a level line so I know where to cement up to. Most people use wooden planks to create this border but as I already had the concrete panels I thought Why not.

Step 7: Posts for the Building Frame

Most builds are not done like this... but I wanted a solid post foundation to build around rather than building sides and fixing together..I couldnt get square long beams 3.6m long so i bought planks 5cmx10cm x3.6 meters. And bolted 2 together. This is cheaper and forces the beam to become straigher.. (yes longs planks/joists are usually a bit wonky.)

Step 8: Postcrete the Scaffolding and Building Posts

Buy 1-2 bags of postcrete per hole. Postcrete is mainly used for cementing fence posts... so this stuff is ideal.. its goes hard in about 3-4 minutes... put the post in check with a level its verticle add water.. then add the postcrete and start poking/mixing with a small metal or wooden pole.

Step 9: Cementing the Foundations

I did consider renting a couple of cement mixers but because of the amount I had to do it was easier to get a guy with a cement mixer lorry. Yes “hard work” was still involved I got a couple of pals and my brother to help offload the concrete (cement & ballast) by relaying 2 wheelbarrows between the lorry and the garden… It took us around 2 hours to offload 7 cubic meters of concrete. While this was getting spread out level with a long wooden plank. As best you can..

Step 10: Building the Frame

As you already have the main building posts sticking out the ground all we have to do is build the frame in between it. (Google “DIY studwall partition” for more help on building this frame) Start by measuring the distance between each gap, then using a 5cm x 10cm plank, mark and cut. You want to create a rectangle shape, and lye that on the ground in front of where it will stand up. This is put together on the floor so you can easily get to all sides top and bottom to drill. Once you have your rectangle, slot vertical planks every 35cm. Mark and cut 5cmx10cm planks and place horizontally in-between these vertical planks to strengthen it…(these are called noggins)..

Buy windows and door before doing this so you know the size of the frame to build. Lift the completed frame up from the floor… Hopefully very tight…Wedge it between the cemented posts… Use a hammer if necessary...I also used my steel toe cap shoes to kick it into place J. Once in position screw the frame to the post. Do this all the way around until you have a finished trapezoid shape.. Remember to leave a gap for your windows and door. Side note: Buy wood screws!!! I use Torx for most of this project because they don’t require pre drilled pilot holes. They just screw straight into the wood with no hassle and hold very strong.

Step 11: Building the Roof Rafters

This is pretty straight forward, you start with a 5cmx 10cm long plank (same as the others we have been using). Then cut a short piece to go vertically to make a L shape (the size will depend on the angle you want for the roof so just say 60 cm for sake of argument.) Cut a diagonal corner off both these pieces so the third piece will fit perfectly on top to form a triangle. Then it’s just a case of cutting pieces of wood to go in-between... Same as the stud wall frame every 35cm. Once this is made pop it on top of the frame (left hand side) and then do the same on the right hand side.. My Gym has the water run off to the front of the building so I can get to the drains easily, but some people have it to the back or even to the side.

Step 12: Building the Roof

I mentioned the I-Joist earlier these are ultra-strong man made roof joists. Made of layered plywood and OSB board. I used these as they allowed for a 6m width without the need for a support beam in the middle. It was then just a case of putting them on top of the roof rafters every 40 cm and screw in. To add extra strength I hammered herringbone struts to the I-Joists. These are basically metal plates that stabilize the joists together.

Step 13: Roof

I bought some green polythene vapour barrier from Wickes and wrapped the whole structure in it by stapling (using heavy duty hand stapler) it to the frame. This stuff stops moisture penetrating to the wood frame. I then pinned black corrugated bitumen Sheets (950 x 2000mm) one after the over using special corrugated roofing nails. Remember to make the sheets sit 15-20cm over the edge of the front so the rain runs off the building. I chose this material rather than the usual plywood/roofing sheets because it was 4 times cheaper and 4 times lighter. You just have to be careful how you put your weight on the sheets has these can dent. Last thing for the roof is to then cover it with Bitumus paint…sealing the nails you just hammered and any gaps in the sheets. (remember to overlap by 1 hole ridge).

Step 14: Windows

You can get whatever windows you want, I had some 60cm x 160cm double glazed PVC windows and just drilled them straight into the frame.

Step 15: Cladding

Bought loads of 11mm OSB board (half the price of plywood) and drilled it straight into the frame from the outside. As this is ugly and my structure is in my garden I cladded the outside with feather board, over lapping the edge by about 4cm. I used decking screws not nails because it allows for mistakes and I think is overall much stronger. *A little tip: wet the feather boards first to prevent snapping and cracking as you clad. Varnish or paint can be applied once everything is done.

Step 16: Run the Media & Lights

Run your TV wires, lights, HDMI connections and speaker wires while your structure is still exposed inside. I had speaks 1 power socket, 4X 40watt speakers and 10 LED lights.

Step 17: Insulation

Depending on your budget you can buy the rolls or foam boards. I could only afford rolls, works just as well. Ok so cut the rolls with a saw 35cm wide, as this is the width of our frame, unroll and stuff like a cuddly toy. The ceiling is a little bit harder as the roll will want to fall down… Use string underneath the part that is drooping to hold in place and continue stuffing. Alternatively use the heavy duty stapler.. Once this is done I cladded the inside in OSB board.. Why not plasterboard>> Because we are building a sparing gym and people may run into walls :).

Step 18: Plasterboarding

Plasterboard the ceiling, you will need a friend to help you….Just hold the sheets up, then using drywall screws, screw into the I-Joists. Use plasterboard tape across where the board edges meet. Get some Wickes ready mixed plaster skim 5kg. (Comes in a small bucket) and skim over… This bonds the edges.

Step 19: Get an Electrician

Get a certified electrical guy to fit a mini consumer unit that connects to your house consumer unit, fit the lights and connect them.. He will give you a certificate if he’s not 100% dodgy.

Step 20: Flooring

I used a few layers here. First I put down the tarpaulin I already had (it was acting as a temporary roof), got some ordinary foam board (for insulation) cut and placed on the floor, some more OSB board that I drilled into the concrete foundation. This creates a bit of a bounce effect, just as I wanted… Then to top it off I laid out gym foam on the floor so I can move around with bare feet... Leave a 3 cm gap around the border so when the temperature changes the foam will expand slightly but will not cause mounds in the middle.

Step 21: Paint, Decorate and Add Toys

Here’s my list of toys to dates: Century Sparring Bob 4ft Punch bag Boxing Wrecking ball Speed ball Ceiling to floor ball 9 pairs of Nunchucks 38” TV mini DVD player/card reader & Xbox 360 with Kinect Interactive games include Kung-Fu High Impact, UFC trainer, Nike Trainer and Fighters Uncaged. (last game is excellent for shadow boxing) And that’s all….I know more dimensions/ details probably could have been given but this is just a basic guide to inspire your gym/Dojo.



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    8 Discussions


    2 years ago

    Amazing work.!!!!

    How much did you spend?


    2 years ago

    Well done Grasshopper!


    2 years ago

    Well done Grasshopper!


    2 years ago

    Ciao! Very great work! How many time did you spend to do all this?

    1 reply

    2 years ago

    Great job, Train well now :)


    2 years ago

    Whoa, this looks like so much work!

    It really looks like it came together nicely though. Impressive! :)

    1 reply

    Reply 2 years ago

    Yeah it took a couple months to make.. Most people wont copy my build but Im hoping some elements will help.