The selection of climbing holds is the single most important element of a good home bouldering wall. Holds will probably be the most expensive budget item for your wall, so you'll want to make sure you spend your money wisely. When you're outfitting a new wall, having enough holds and enough variety are the most important considerations. Later on, as you add to your existing selection, other criteria will become more important, but for now, focus on maximizing your hold buying dollars to get the biggest variety you can. Metolius offers large sets of holds with many different sizes and styles. These packages offer the best value for setting up a new wall. When you're shopping around, remember to compare the size of hold you are getting as well as the number of holds. One manufacturer might offer a 50 hold set for the same price as another manufacturer's 40 hold set, but the 50 hold set might be full of smaller holds. Hold prices are almost entirely dictated by the amount of material in the hold, so make sure you're considering like-sized holds when comparing prices.
A good rule of thumb is to have at least one hold per square foot of wall surface. That means 32 holds per full sheet of plywood. When you're starting out, you can get by with 15 to 20 holds per sheet, but the more holds you have, the more fun and interesting your wall will be. Many home walls end up with over 100 holds per sheet of plywood.
For now, don't worry too much about the specific hold shapes, just make sure you have the right mix of hold types. The bulk of your selection (about 60%) should be medium-sized blot holds of every possible style (edges, pockets, pinches, slopers, etc.). About 20% of your selection should be footholds. These can be small bolt-on holds or screw-ons. Screens are ideal for plywood walls. They're a great value; they will go places where blot holds won't, like in front of framing members or in corners, and they can be made thinner than bolt-ons, so they make climbing on plastic more technical and realistic. The only downside is that screens are somewhat less durable than bolt-ons. About 10% of your selection should be small handholds. These will be very similar to the footholds, but slightly larger and more positive. Again, maximize the value and variety that screw-ons can offer. Much of your small hold selection will work as either hand or footholds, so don't get too hung up on the difference between the two styles. Just try to make sure that about 30% of your total selection consists of a good variety of small holds. Depending upon the angle of your wall and your ability level, 10 to 20% of your selection should be jug holds. Metolius offers a wide variety of mini jugs. These are great for home walls because they take up less space than full-size jugs and they are substantially less expensive. Finally, be sure to get some specialty shapes like corner holds, low-profile plates and rails, big slopers, etc. to keep things interesting.
Most commercially available climbing holds attach with 3/8" socket head cap screws. There are 3 different styles of heads that are commonly used. Each different style works with a different shape of bolt hole in the hold. It is very important to use the correct style of bolt. The most common style is the standard socket head. This is the strongest, but it also has the highest profile. These bolts require a 5/16" hex wrench. Low-profile holds require the use of bolts with flat heads or button heads. Flat heads have a flat top and tapered sides, which match a tapered countersink in the hold. Button head bolts are often used on thin holds that have no countersink. Usually, you can substitute a standard socket head bolt for a button head, but it will stick out farther and may interfere with the intended use of the hold. Flat heads and button heads use a 7/32" hex wrench. Never substitute a socket head or button head in a hold that was designed for a flat head. It will weaken and possibly break the hold.
Different holds require different bolt lengths. It is critical to use the correct length bolt for your safety. On a home wall that uses 3/4" plywood, the bolt must stick out from the back of the hold at least 3/4" in order to fully engage the T-nut threads. It is okay to use a longer bolt as long as there is enough space behind the wall to allow you to fully tighten it. Longer bolts usually have a shoulder or unthreaded portion behind the head. Make sure that the shoulder doesn't extend past the back of the hold or you won't be able to fully tighten it.
Most manufacturers include the correct bolt with their holds, so there is no excuse for using incorrect hardware.
Screw-on holds are ideal for home walls. These holds attach to wooden walls with self-drive screws. Because many screw-on holds are quite thin, they can be relatively fragile. It's best to attach thin screw-ons once and not move them. They are so low-profile that usually they won't interfere with other holds, so there is little disadvantage to installing them permanently. If you are using a power drill or screw gun to install your screw-ons, set the clutch to the lightest setting. Try not to drive the screws all the way in with the drill. Finish tightening them by hand so you won't break as many holds. It is a good idea to use construction adhesive or epoxy in addition to the screws. This will vastly increase the life span of tiny screw-on holds.
Now it's time to put your holds up. Get a couple of good T-handle hex wrenches to make this task easier. The bottom panels of your wall should contain mostly footholds. If you're using screw-on footholds, make sure you attach them far enough from existing T-nut holes that they won't interfere with attaching bolt-on holds later. Fill the bottom panels with as many different footholds as possible, but save a few holes for starting jugs. Home bouldering walls will have plenty of problems with sit starts, so you'll need some jugs low down. It's good to use a lot of underclings and side-pulls for starting jugs so they don't end up as enormous footholds once you've climbed past them. You'll also want to put a few jugs at the top of your wall for finishing jugs. Obviously, the top panel or two won't need any footholds, so use any remaining footholds on the bottom half of the wall. Now fill the rest of your wall with the remaining holds. If your wall has multiple angles, you'll want to put most of the bigger or more positive holds on the steeper areas and vice versa, but try to mix it up and keep the variety as high as possible. Remember that any given hold can be oriented to pull straight down, sideways, as an undercling, or anything in between.
Making boulder problems can be as simple as picking a few holds at random and pulling between them, but the more thought you put into designing your problems, the more fun they will be. Try to employ the widest variety of moves that you can; don't be afraid to include sideways or even downward movements in your problems. Think of every different hold as a potential side-pull or undercling (e.g. don't fall into the common rut of only pulling downward on pockets.) Avoid using big footholds. They won't help you improve your technique or develop good core strength. Experiment with footwork by designating problems as "open" (any hold on the wall can be used as a foothold), "tracking" (only the designated handholds on the problem can be used as footholds), "screw-ons" only, or designate specific footholds for each move.
You'll want to develop a library of problems, so when you set a good one, mark it with coloredtape and record the start and finish holds, number of moves, color of tape, footwork restrictions, etc. in a book.
Time to Climb
With your wall finished and intoxicating visions of burning-off your climbing partners with your newfound power clouding your judgment, you'll want to jump on that thing and start training like a circus monkey. Be careful! Home bouldering walls are so convenient, efficient and fun to use that it can be easy to develop over-use injuries. Always warm-up thoroughly and make sure you're getting plenty of rest between sessions. Over-use injuries are often the result of muscular imbalance so it is important to work your antagonistic muscles as well. (These are the muscles that are opposed to those used in climbing, mostly extensor muscles like triceps, pectorals, finger extensors, etc.) Perform some push-ups and dips for your chest and triceps and use a Metolius GripSaver Plus to balance the muscles of your hands, wrists and forearms. Follow this simple advice and you'll soon be on your way to the best climbing season you've ever had.