With the popularity of Ninja Warrior growing many people are looking to build back yard obstacles. This is an instructable on how to build a low cost warped wall for less than £100. To save on space and cost the wall was built against the house to provide the solid support and therefore required minimal wood. I was not interested in the pull over the top as for me the main challenge is reaching the top bar. However to add that feature you would simply need to build the whole structure further out and add a top platform.
Step 1: Bill of Materials
8off - 38x63x2400mm CLS timber
2off - 18x1220x2440mm MDF Sheet
1off - 9x1220x2440mm plywood Sheet
1off - white external masonry paint
Step 2: Weather Protection
Because keeping things cheap is the name of the game I bought untreated wood. Not normally advisable for external work but when you give every surface a generous double coating all is well. Even the MDF works outside once carefully protected. So the first job was to give my CLS timbers a double coat of white paint.
Step 3: Drawing the Curve
So a warped wall is 14 foot high and I went for a curved radius of 10ft offset by 1 foot.
For those quick on the calculations you will notice that two sheets of MDF does not give the required height but we will just use the cut-offs to complete the top section.
First lay out the boards in a large area (I used my lawn) in the arangment shown. Then using a 10ft piece of string attach one end to a screw driver and the other end to a pencil. I left a gap of about 80mm from the back of the horizontal and then measured 10ft out. Then I measured 9ft up from the vertical (1 foot offset) and stuck my screwdriver into the grass. This allowed my pencil to pivot on the the screwdriver. Using this set-up I drew the curve on the wood. I left the screwdriver and pencil in place for finishing off the curve later once the cuts had been made.
Step 4: Cutting the Curve
This is best done using an jigsaw. Once the curve is cut on each piece take the cut out piece and use it as a template to draw the mirror image piece on the same sheet of wood. Then cut that out too. So each of the two sheets will produce two identical sections of the curved wall. The middle curve section, because its a thinner, will have a larger off cut and this can be used for the third and final section of the curve. So using this off-cut I laid the lower and middle two curves back down on the grass with the off cut at the top and using the pencil again drew the final curve section taking the wall section up to the final 14 foot height. Again I cut out the final section and used it as a template to make it's mirror image.
All the pieces were then painted both sides, two coats for weather protection.
Step 5: Construction
First I attached the CLS wood to the side of the house. Two lengths separated by 600mm. It's 600mm wide because then you only need one sheet of plywood, cut in half lengthwise to sheet the ramp surface. Keeping costs low. 600mm is also all you need to run up. I have never felt the need for a wider ramp. Once the CLS wood is attached to the house then the cut sides of the ramp can be attached. I cut a hole in one of the bottom sections so that my boys can use it as a little hide out.
Once the side are in place I then used the remaining 4 lengths of CLS and cut batons to fit in between the sides to give support for the ramp surface. I put the lengths pretty close together near the bottom of the ramp as that is where the biggest force will be exerted in running up the ramp and I increased the spacing significantly as the ramp progressed closer to vertical as there will never be any feet placements at that height.
Step 6: Adding the Surface
Cutting the plywood sheet in half lengthways gives plenty of scope to sheet the whole surface but I only did it until the 12 foot mark. This allowed me to have a catch beam at the 12 foot point as well as the 14 foot point as a practise progression.
The plywood sheeting was simply screwed into the batons and then painted with a double coating. The coating has proved durable although the 9mm plywood has only just been strong enough with the close baton placements to withstand the force of running the ramp. I have noticed small splits in the wood on the underside after a good amount of use. Maybe a slightly thicker plywood would be advisable but will be much harder to bend... so it's a trade off.
And that's it all finished. Warped wall construction on a budget. Now all I need to do is get back onto Ninja Warrior UK season 3 to test my improved skill! Happy building. Let me know in the comments if you have any questions.