The boxes shown fit under a staircase with a 45-degree pitch: For every 12 inches the stairs rise, they run (travel horizontally) 12 inches. The boxes step up and over in 12-inch increments. If your stair slope is more gradual, your boxes will need to be wider to fit; more steep and the boxes will be narrower. To find out, hold a tape measure vertically with the hook on the floor. Move the tape along the bottom of the stair until the distance to the floor is 36 inches. Use a 4-foot level to make sure the tape is plumb, then mark the point on the floor. Measure from the floor mark to the point where the bottom of the stair meets the floor. Let’s say the distance is 46 inches. Divide 46 by 3 to get 15-5/16 inches. Now you know your small boxes and tall box need to be 15-5/16 inches wide while your large boxes should be 30-5/8 inches wide. These boxes are built for utility, not beauty. They are made from inexpensive particleboard without finish, although you can paint them for a more attractive look. One word of caution: Don’t build the boxes with particleboard if your basement is damp. Particleboard readily absorbs moisture that makes it swell, and it will crumble if it gets wet. Use CDX plywood instead. This inexpensive grade of plywood, intended for exterior sheathing, is made with water-resistant glue. Expect to spend about 4 hours building the shelves. Before you begin, measure the slope of the stairs, assemble tools and materials, and prepare a work area. Many lumberyards and home centers have a panel saw—the best tool for cutting sheet goods to size (pictured above, right). A panel saw has a rack that holds the panel upright and a circular saw that runs on tracks to easily make accurate rip-cuts and crosscuts anywhere on the panel. Ask your dealer to make the crosscuts described in Steps 1 and 2 and the rip-cuts described in Step 3. This will speed your work when you get home, and the smaller pieces will be easier to transport. Lay the tall box sides (H) next to each other, with edges flush. Draw lines across both pieces with a framing square to show where to locate the bottom of the shelves. Extend these lines across the outsides of the panels so you will see where to drive screws. Editor’s tip: Always have a small bucket of water, a sponge, and a towel handy when working with wood glue. You can wipe away glue that squeezes out of joints with a damp sponge and dry your hands with the towel. Editor’s tip: When joining the top and bottom of the long box to the sides, put wax paper under the joint to keep glue squeeze-out off your bench. The wax paper will easily pull away without getting stuck to your project the way newspaper will.
