There are some excellent instructions online. You can find tutorials and videos online if you take some time searching around. The gold standard for building rock climbing walls is the guide by Metolius: https://www.metoliusclimbing.com/pdf/How-to-Build-a-Home-Bouldering-Wall.pdf

Here is another one from Atomik: https://www.atomikclimbingholds.com/how-to-build-a-rock-climbing-wall

Vertical walls are by far the easiest to install. You need to put furring strips horizontally along the wall. This allows you to keep the actual rock climbing wall off of the house wall to give space for t-nuts/bolts to secure your holds.

For furring strips, some recommend 2x6s; we used 2x4s which we think was quite adequate. The smaller size wood allows you to put more holes for t-nuts. We spaced the furring strips about every 18-20 inches; others have recommended 16” spacing but we wanted more space for holes/holds.

  

Make sure that use buy kiln dried (KD) wood; if you buy green wood (that means its likely still wet), make sure to let it dry out for at least 4-5 days in the garage. If you put it on the wall before drying out, it will likely mold/mildew the wall. Kiln dried is also better because it is less likely to warp than green wood.

Use a stud finder and try to hit the center of the studs. We used 2 screws per stud for each furring strip. We used 3.5 inch star drive screws [like these] (star screws are really great compared to standard Philips; needs less pilot hole drilling, super easy to drive in, tons of pulling power). You want to use at least 3.5 inch screws if going through drywall – you could easily argue to use 4 inch screws. We pulled off the baseboards and saved them if we ever decide to get rid of the wall or move.

If you do any overhanging wall (highly recommended), some recommend using 2x6s for the joists; we decided to use 2x4s because we wanted more space for holds on the arête. Seems to be holding up just fine. We used 2x6s for the header joists (where the overhanging joists insert into the ceiling and wall).

 To connect the header joists to the wall/ceiling, we used 4 inch lag bolts for a little bit of extra strength since there would be additional stress at these points. In order to figure out the angle we wanted, we used a little trigonometry to figure out where to put the header joists. To attach the overhanging joists to the wall and ceiling, we used standard joist hangars. We spaced the joists 16” apart. We inserted a handful of blocks between the joists as recommended. 

For added strength (and also because we wanted to put a little play area in the wall), we inserted several additional supports that connected the furring strips to the overhanging joists. We’ll come back to these additional supports later.

For the actual climbing wall, you want to use ¾ inch plywood (23/32 inch is fine as well). Typically, you want to use some sort of hardwood plywood that is paint-grade (meaning it is flat). You don’t want to use oak because it is hard to finish as it has an open grain. Use something like maple, birch, etc. Our homedepot/lowes had some sort of pine (paint grade) once that I got for something and it worked out fine. I honestly don’t remember what kind we got for the rock climbing wall. You want something that is smooth and looks high quality – you don’t want the knotty/unsanded variety – just not worth the few dollars you will save.

Cut the plywood to the size you want to fit your design. Some people say you should drill the holes for the t-nuts first, install t-nuts, then paint (and protect the t-nuts by inserting golf-tees). That sounded crazy backwards to us. 

After cutting the wood, we primed 2-3 times and then painted everything exactly as we wanted it. I wasn’t in charge of the painting – I’ll take no credit for that.

After painting, I was afraid that we might tear off some of the paint – so I wanted to provide a little extra protection. We ended up using, Minwax Polycrylic water-based protection finish in clear matte. We used all different kinds of paint on this wall (whatever we had laying around in the right colors) and the Polycrylic ended up cracking some of the paint colors (cracks that look like what happens in old oil paintings). You can only see it when you are closer than about 4-5 feet. Knowing that, would we use it again…? Probably – I think it has protected the wall. You don’t want to use standard oil-based protection coatings because it will yellow the paint. We’ve had the rock climbing wall up for about a 6 months now and the colors have stayed true.

After painting, we figured out exactly where all of the furring strips, joists were going to intersect the plywood; and then drilled holes for the t-nuts. I went back and forth on which drill bit to use. We had two options already on hand in the right size (7/16”): a normal drill bit (the spiral kind) and a spade bit. I tested both of those out with inadequate results; so I decided to buy a forstner drill bit. Forstners are generally used to create a hole that leaves a flat bottom (cabinetry, etc), but they are also very useful for having very sharp edges. I couldn’t find my normal 7/16” drill bit when I did this test, but the results would have been the same. We bought our forstener drill bit for something like $10-$12 on amazon (homedepot/lowes didn’t have the right size in the store). I’ll probably never use it for anything else, but it was money well spent. Below is a picture of a test strip I did; forstener on the left, then normal drill bit, then spade bit – there is a huge difference. The next pictures are examples of how the forstener bit did on the painted wall. The first picture shows no damage at all with the 2^nd picture showing slight tear out – this was about the extent of any damage the bit caused. 

Make sure you drill the holes straight! If you don’t drill them straight, your bolts won’t go in very well and it will create a huge headache later. I thought about building a jig to make sure I drilled them straight but was too lazy and just went for it – I had no problems. You’re supposed to put something like 72 holes per sheet of plywood. Do you use a standard pattern or random? You can look for all of these answers and here debates back and forth online. We did about 80 holes per sheet and did random drilling.

After drilling the holes, next came t-nut installation. You want to use t-nuts so that you can move the holds around whenever you want. You have to get 3/8” t-nuts – these are the standard for rock climbing. There are 2 main varieties: the 4-prong t-nut (with spikes) that you hammer in and the round base t-nut with 3 screws for attachment.

You easily find both on amazon.com The 4-prong is substantially cheaper but not nearly as good in quality. Save yourself a huge headache and get the ones with screws for attachment. Either way, I recommend putting a drop or two of super glue between the shaft and the plate so that it will contact the plywood – the last thing you want is t-nuts that don’t stay put. I like the screw-in t-nuts because you screw it in and you are done.

If you use the 4-prong, don’t pound them in with a hammer (they won’t stay); instead, attach using the technique demonstrated in this video: http://www.threeballclimbing.com/install4prongtnuts.htm

After t-nut installation, you are ready to put the plywood on the wall!! Attach with 2” inch screws (again, I prefer the star-drive variety) spaced about every 6-8 inches. On any overhang, be generous with the screws and make sure you put them into the joists and the blocks between joists.

You’re done!!!!! Congratulations. It really isn’t that complicated. After you’ve done it once you could do it again and again. The last thing we did was to install our secret hide-out. On top of several of the additional supports we put on the overhanging wall, we placed some left over plywood to create a platform.

We also didn’t place arête all the way up so the kids could see out. This is probably the favorite part for the kids – but I wish I had holds where the arête should be. After losing a favorite Pokémon card between pieces of wood in the tree house, I ended up caulking the edges so nothing could fall through.

One of the most expensive things you will buy are rock climbing holds. It all depends on who is going to be climbing. You still want good and safe holds, but if kids are the only ones that are going to be climbing, you can probably go a little bit cheaper. We wanted to keep it cheap (and holds are not cheap) and we ended up using a combination that was favorable for us.

 The first we bought were from Rocky Mountain Climbing gear (https://www.rockymountainclimbinggear.com/) - you can also buy their stuff on Ebay and Amazon as well. The quality is not stellar. The holds are hard and stiff; grip is not great; and some have relatively sharp edges (not good). But they are super cheap – if you need a bunch of holds on your wall, this will help you fill it up fast. We use the nice ones for hand holds and the not so great ones for large foot holds. The nice thing is that you need lots for feet and these are usually big enough that you don’t need rock climbing shoes.

Then we bought most of our main handholds from Synrock. Its run by a guy named. Jim. You just email him, tell him what you want, and he sends you a Paypal invoice. They got to our house in about 7 days – so don’t think they’ll turn around like amazon.com. It’s a little 1990s – but I love the holds. You can also find him on Ebay (but its cheaper on his site). They are made of ceramic which is relatively brittle. So you can’t toss the holds around; you have to be sort of careful putting them on your wall. I put holds on by hand and I haven’t broken any. They are relatively heavy – but I could care less. Jim puts a lot of effort into making these holds nice and rounded- no sharp edges at all. The ceramic has a super nice texture to it – very nice on the skin; it is cool to the touch as well. Have you ever climbed on new plastic holds? The texture is so rough that it tears your skin right off on an overhang. These are super skin friendly. Oh, and they are also super cheap. I loved our first set so much that I bought another – and I think I’m going to buy some more. I wouldn’t mind trying out some other company (Atomik or another), but the holds are more than twice as expensive – I just can’t justify spending that much more money for something that doesn’t feel as nice. 

I have also dabbled in making our own holds out of wood. We found an old bed-frame for free on someone’s lawn. It wasn’t complete and I decided it would take to long to refinish. The posts are 3x3” made out of oak. So I’ve been whittling that down into some holds that I don’t have: some slopers, edges, and a few crimps. The problem with making holds is that it takes a fair amount of time.