1 Algorithm based on impact on opinions over time - and Wikipedia. 2  Top ten most significant in history puts Jesus in the number one spot.  The list also includes Muhammad, Lincoln, Hitler and Shakespeare.
Plies vary in thickness from 1.4 mm to 4.3 mm. The number of plies depends on the thickness and grade of the sheet but at least three are required as the minimum odd number of plies. Roofing can use the thinner 5/8 (15 mm) plywood.
One of the main advantages of plywood is its stability -- it's laminated in layers, so it doesn't sag as easily as solid wood. Another advantage is its cost. A sheet of fir-faced plywood that gives you enough material for eight 1-by-4-foot shelves costs less than $40; hardwood-faced plywood costs about 50 percent more. The minimum thickness you need for shelves is 1/2 inch, but if you plan to load them with heavy items, use 3/4-inch plywood. When You Need Wood Pre-cut wood shelves are readily available, and most of them are made of pine.