Make a Climbing Wall
Framework. Each section of a framework should be made separately from the anchor and structural support trusses. Lay out the outer framework on the floor.
Tack the outer frame pieces together with a small nail before you are square the frame. This is done to keep the pieces from moving out of place as you make adjustments. Measure and mark the locations for the inner studs. Make your measurements from the same side at the top and the bottom. Assemble the panel framework using screws. Drill two holes with an 1/8" drill bit at the locations the screws will be installed. This will make it easier to screw the joints together without having the Phillips driver bit pop out and strip the screw head. Re-check the square of the frame, then screw the frame together.
Check for Squareness. Measure diagonally from opposite corners. Check the distance of both diagonals. Both diagonal distances must be equal, if the are not equal, the frame is skewed. Adjust the the frame until both diagonal measurements are equal. This method is far more accurate than trying to use a framing square. Tack the frame together using 10-penny nails. Leave about 1/8" of the nail head sticking up so you can remove the nails later.
Joints inline at equal angles. Studs and joists should be joined together in-line, and reinforced with plywood with screws, not nails. If studs or joists join at an angle, cut equal angles from both pieces. If you must overlap a stud or joist, secure the two pieces using a 1/2" nut, bolt with a washer. The type of fastener is determined by the design specifications, how much weight the joint needs to support. Seek advise from someone familiar with framing.
It is important that your joints are at least as strong as the structural members they connect.
Anchors. The piece that provides the anchor to the climbing wall is called the ledger (sometimes called header) board. Fasten the ledger to the wall using lag screws by drilling pilot holes 24", staggered 2" from the top and 2" from the bottom of the ledger board. Use a washer over the lag screw to prevent the head from pulling into the wood. Use joist hangers to attach the joists to the ledger board. If your climbing wall is vertical and extends to the floor, it will distribute vertical force to the floor. Anchor to the ledger at the top plates and bottom plates of the climbing wall framework. Secure the top plate of the climbing wall to the ledger using two screws per joist, one on each side. If you have a low overhanging section, the ledger board will support the full dead weight of the roof, climber and dynamic live loads created by the force of the climbers moving on the climbing wall.
Joist Layout. Long joists will not be perfectly straight. Before installing any long wooden member, check for straightness by sighting down the edge. The high side is called the crown. Position the crown at the top. A joist will rest on top of a beam or will anchor to a ledger or header board (which attaches to an existing facility). You can measure from either end of the anchoring ledger. Joists must be spaced on 16-inch centers due to the additional weight they must support. Set the joists in place and check for square to make sure each joist is perpendicular to the ledger. Mark the locations of the joists using a pencil. Toenail the joists in place temporarily using 12-penny nails. Predrill holes for screws, one on each side. Attach the joists to the beam or ledger using screws and remove the temporary toenails.
Drill T-nut Holes. It is much easier to drill these holes on a set of saw horses than when the climbing wall is already put up. Place two sheets of plywood together and face up on saw horses or some construction bench. The sheets should be face up (climbing side up) when you drill the holes. It may or may not matter to you which side of sheathing you climb on. But if it does, make sure you drill from the "climbing side". This will cause the splinters from drilling the holes to be on the other side. Why use plywood? See Plywood vs OSB for Use on a Climbing Wall.
T-nut holes spaced every 8" Start pattern 4" from edge
Clamp the plywood sheathing together. Drill t-nut holes for two sheets at a time. This will save you time... Using a pencil and straight edge or chalk line, mark parallel lines on the sheet 8" apart. Start this pattern 4" from the edge as shown. Using a 7/16" bit, drill through both pieces of plywood. This grid spacing will give you 72 t-nut holes spaced equally without hitting a 2x4 and will give you the flexibility to space the 2x4 supports at either 24" or 16" spacing. Do not install the t-nuts at this time. Wait until you have cut the pieces of plywood to fit the shapes of the climbing wall. If you install the t-nuts now, they may be in the cut line. You cannot cut through a t-nut, so you will have to remove it if it is in a cut line - better to wait until the pieces are cut, then install the t-nuts.
You may need to cut sections of the panel (depending on your design) to make shapes for the climbing wall. If the t-nuts are installed at this time, they interfere with cutting the sheathing.
Cut Sheathing to Size. If you have designed anything other than a wall with 4x8 sheets, you will need to cut the sheathing to fit. You have the framework complete so you can measure the exact dimensions directly from the framework.
Do not install the plywood sheathing at this time.
Install T-nuts. Install the t-nuts from the opposite side that you drilled the holes. So, if your plywood sheathing is still on the sawhorses, turn them over. Put some wood glue or white glue in the t-nut opening. use your finger to spread the glue around the inside of the hole. The glue does several things: 1) it seals the open fibers in the t-nut holes. This will prevent moisture from getting into the fibers and loosening the t-nuts; 2) helps anchor the t-nut in place. While the glue is still wet, install the t-nuts in the holes. Use a hammer to get the t-nuts completely flush and seated. Get the t-nuts seated firmly in the holes. Make sure they are straight and flush with the surface of the plywood. This is an important step. There are many t-nuts in 4 sheets (288 of them) and your arm will get tired swinging the hammer - but make an extra effort to get them in all the way seated, flush and straight. After the climbing wall is put up it will be much harder to correct a poorly seated t-nut.
Install Plywood Sheathing. Now is the time to double check the framework. You can strengthen bracing much easier before the bracing is installed. Hang on the framework, make sure it is secure. After the framework is made, the t-nuts are installed, the sheathing is cut to size... lift the sheathing to their frames. Tack the sheathing in place using small nails. Make sure there are no gaps and the sheathing sections do not overlap. If everything is ok with that section, go ahead and screw the sheats in place using self tapping screws. Continue installing the pieces of sheathing for all sections.