How to build a Box Jump – Part 1:Overview & The Lip

The intent for this multi-part article is for the average BMX or Skatepark rider to be able to build a decent box jump with a minimal investment.

Usually I start any project with a bunch of “napkin sketches”. This preliminary work will help shape the project early on. I have started down a project with a bunch of money and time invested and then had an un-anticipated change or hiccup which causes the project to either stop, slow, or cost more. As you decide what your box jump is going to incorporate, keep in mind that obviously the more elaborate you make it, the more it is going to cost.

A few ideas:

• Get friends and said friend’s parents involved, maybe one or a bunch of them would be willing to go in on the cost.
• Start out with a ballpark figure on what you think you can afford, again some quick napkin figures with an accompanying call to Lowes or Home Depot should verify whether or not you need to think smaller or possibly get more elaborate with your ideas.
• Have an area where this behemoth of a jump will not have to be moved. Believe me, moving a 20’ Box Jump is no fun!
• Make the Box Jump sectional. This is the best idea that I had for mine, so if you do have to move it, it is feasible.
• Make the landing curved. This is the worst thing about my box jump, the flat landing (other than the fact that it is 5’ tall, more on that later).

Let’s get started.

I wouldn’t recommend a box jump any taller than 4’. Mine is 5’ tall and to clear it, you have to go big all the time; there isn’t really a choice to racer it….

I will make suggestions, feel free to add your own numbers…

The Box will be 3 sections, the lip, the deck and the landing. So we are going to build a 3’ 10-1/2” tall box (this is so that 1 – 8’ sheet will span from the bottom of the lip to the top with out having to add any little strips) with a 7’6” radius lip, a deck of either 8’ or 10’ and a radiused landing with a 2’ radius at the crown and a 20’ radius for the body of the landing. You also have the choice to make it either 8’ or 12’ wide and I wish I would have forked out the extra dough for 12’ as it is kinda scary 360ing the 5’ box out back with such a narrow landing. Side Note: When I made a visit to Utopia in Raleigh, NC,their box was nice and wide which made trying things way less scary.

The Lip:

So, we are building a 3’ 10-1/2” tall lip which works nice with whole sheets of plywood. You should be able to get both sides out of 1 sheet (see diagram below, click on for larger image).

There are 2 ways of construction for the lip, I have always done it the old school way using1-1/8” plywood and notching the plywood for the ribs. This is time consuming and the ribs are harder to attach to the side sheets, but it is stronger. The easier faster way which will also allow you to use 5/8” to 3/4″ plywood is to just nail thru the side sheets and into the end grain of the ribs for the lip. If you are going to build it this way, I would recommend galvanized ring shank nails or the proper sized and coated screws as they have less of a tendency to loosen over time. Let’s assume you made the wise choice and went with the 12’ wide option. I would put the ribs at 8” on center if you are using 2X6s or 6” on center if you are using 2X4s. You will need (14) - 2X6X12s or (18) - 2X4X12s. I searched on Lowes website and 2X4X12s are $2.73 ea. & 2X6X12s are $3.99 ea. (At Lowes in Medford, OR as of 1/24/08). So total cost on 2X4s is $49.14 or 2X6s is $59.85. One sheet of 15/32 CDX is $25.77, 23/32 CDX is $31.88 and 1-1/8” T&G Sturdifloor is $36.88.

Lay the studs out in this fashion for 2X6s:

Lay the studs out in this fashion for 2X4s:

You must measure point to point for the ribs, by that I mean you measure from the end of the side pieces at the ground and mark up the plywood 8” for the first rib. Measure from that first mark, 8” up, to the second rib, and so on… If you lay out all the marks from the bottom, your ribs will be closer together than 8” and your plywood break will not land on a rib (for larger ramps). Same instructions for the 2X4 Design except spacing is changed to 6”. Toe nail the ribs in, nailing thru the plywood from the side into the rib so that if they warp or whatever, they will be pushing against the nails.

So your framing is all nailed up, last thing is to put on the sheeting. I have been able to bend 15/64 CDX with pretty good success; it will bend one way and not the other. I have seen quite a few ramp builders put it on an angle like a 45, but I just run it vertically. You will need a few friends to start it and I work from the bottom to the top. You will need (3) – 15/64 CDX sheets of plywood for a plywood cost of $77.31. I on occasion have had one want to break, in this case, I get it wet on both sides and let it set over night, that usually does it. If you have a sheet that just does not want to bend, then use it for the deck or something else. Also, if you have a decent budget you can go on to purchase Skatelite™ or some comparable product and it depends if it will be indoor or out door. For an indoor box jump, you could just purchase Masonite or something like that (Masonite might be too slick). My box jump is out door and sees from 100s in the summer to 20s a few nights in the winter. I usually have to paint it yearly as it is only plywood. I would use screws to put the plywood on as it is the first thing to go bad and consequently the first thing needing replacement. You can purchase returned paint at any local paint store and it is usually $5.00 a gallon. I get 15 gallons at a time of some really good out door paint, and mix it all together so the ramp is a uniform color. I add some sand to the paint which enhances grip and coat it twice.

Site Preparation:

It is a pain in the ass to clear off the site for the ramp,but you should do it. I would recommend putting the ramp on piers if it is to be out in a field or something like that and keep the grass and crap off of it as wood ramps will rot if constantly exposed to water where they can not dry out. If it is on asphalt or concrete, I would still shim it up to protect it as best as possible from water damage and add a piece of sheet metal to the front bottom of the lip so there isn’t a little bump as you jump it.

Viola! Your lip is done, stay tuned for part 2: “The Deck”