Step 1: Define Your Project
Another nice thing about this technique is that finished shelf size is almost unlimited. Shown here is a set of 14 foot shelves I put together earlier from 2 layers of 1/2" scrap plywood. The one-piece boards span 32" between supports and, as you see, can carry a lot of stuff.
The raw material I used would have been thrown away by a sane person. Cracks, splits, warps, nail holes, surface deterioration: it's all good. As long as it's not rotted and has some structural integrity left, it'll work OK. Figure out how much usable area you can get out of your stash, keeping in mind you'll be cutting it into strips the width of your finished shelves, and that you'll need twice the area to start with (assuming 2-ply lamination). Also plan on cutting with, rather than across, the surface grain for maximum strength.
Step 2: Tools and Supplies, and Safety Notes
Stuff you'll need:
- Safety gear: eye protection, work gloves, ear protection, dust mask.
- Circular saw with a carbide-tip blade: a fine-tooth plywood blade is a plus.
- A platform to cut the plywood on; a pair of sawhorses and 3 8' long 2x4s works nicely.
- A pair of 4" C-clamps.
- An 8' long straightedge, such as a piece of 1x3 or MDF molding.
- A tape measure, a square, and a pencil.
- A claw hammer.
- A way to drive drywall screws: cordless drill or screwgun.
- A box of 1-1/4" or longer coarse-thread drywall screws.
- A caulking gun.
- Construction or subfloor adhesive. I used a large tube per 16 square feet of lamination.
- Clamping mass. I used a dozen concrete blocks for 1' x 8' shelves.
- Finishing materials of your choice. I used leftover exterior house paint over a coat of primer.
- Shelf brackets of your choice. I used triple shelf brackets ("Z-brackets") for their low cost and quick assembly.
- And of course, lots of crappy-looking plywood.
Step 3: Select and Prepare the Plywood
- Stagger the joints between segments generously. Keep lots of separation between top layer and bottom layer joints, ideally more than the spacing between shelf supports.
- Keep longer pieces underneath. If your shelves are more than 8' long, a bottom-layer joint is inevitable.
- Make all cuts with, rather than across, the outer grain of the plywood, or in the direction of greatest strength.
- Raggedy corners and edges can be hidden on the lower layer and toward the back.
- Face the worst sides towards each other during glue-up, leaving the nicer sides on the outside.
Step 4: Cut Plywood Into Strips
I set up a pair of sawhorses and place 3 8' 2x4 studs on top to support the plywood. Lay the plywood on top with 2 studs supporting the large part and one stud outside the cut line. This way, both pieces are relatively well-supported when you finish the cut.
Measure the distance between the blade and the edge of the base of the saw. Add this number (1 1/2" for mine) to the desired width of the cut piece (12" for me). This will be the measurement at which you position the straightedge for cutting (13 1/2" for me.) Using the tape measure and pencil, make marks near either end of the plywood, and one near the middle. Place the straightedge on these marks and clamp it in place. Check against the center mark for bending of the straightedge and correct if necessary. You may need to fasten the straightedge to the plywood with a drywall screw if it is especially unruly.
Position the outer stud along the approximate centerline of the piece to be cut off. Set the saw blade depth to 1/4" - 1/2" greater than the plywood thickness. With the greatest of mindfulness, make the cut by guiding the saw along the straightedge. Repeat the process until all your plywood has been cut into strips. Stand back and marvel at how the junky plywood is starting to look more useful already.
Step 5: Lay Out Pieces to Plan Glue-up
Step 6: Glue the Boards Together
Build another board on top of the first board, repeating the above process. Again, the drywall screws will attach to the board underneath, keeping the top board flat. The whole stack will tend to flatness this way.
When the last board is assembled on the stack, place lots of mass on top of the stack for clamping. I used a dozen concrete blocks as shown and got good results. More is always better. Let the whole thing set up overnight.
As I was finishing, it occurred to me that, with the use of lots of long drywall screws, clamping may be unnecessary. The screws aren't wasted as they can be re-used, but there would be a lot of screwing and unscrewing involved. The results might even be better, with fewer small gaps between layers.
Step 7: Unclamp and Finish the Boards
At this point, you'll need to decide on finishing options. Unless they're going in a garden shed, you'll want to do something, if only to avoid getting splinters. I used leftover exterior house paint over primer, which worked well to tack down the loose fibers. Exterior semitransparent stain would also work well if you choose a dark color to hide the ugly. Sand the sharp corners first. Also, if you want to rip the boards to a clean finished width, now is the time to do it. If you want to get fancy, fill and sand any holes and gaps along the edges and surfaces. But really, I was pleased at just how serviceable these shelf boards were with just a bit of edge sanding and paint.
Step 8: Hang Your Shelves!
This is the second set of laminated shelf boards I've made; the 14 footers shown earlier were the first. Besides being cost effective, this technique can rightly be considered green for keeping plywood scrap out of landfill, and using leftover paint just sweetens the deal. Virtually any size or thickness of shelf board can be made this way, and the finished quality is up to the maker. Scrap plywood makes perfectly serviceable utility shelving with a minimum of effort and cash, but you can use this technique with new material to make some really nice outsized shelving that couldn't be cut full-thickness from a 4' x 8' sheet. And a proper finish would allow the end product to pass any spousal-approval inspection. I've thought about making some one-piece, "round-the-corner" shelves this way.