From the Architectural Woodwork Institute, Department of Wood Science; Division of Forestry at West Virginia University, as cited in Popular Woodworking, Woodshop Essentials, Winter 2001:
| Weight it takes to make a 12" wide, 3/4" thick shelf bend 1/4" across a 36" / 48" span | ||
|
Material: |
36" Span | 48"Span |
| Yellow Poplar: | 284 lbs | 117 lbs |
| Hard Maple: | 313 | 232 |
| Red Oak: | 313 | 232 |
| Birch: | 348 | 146 |
| Birch veneer-core ply: | 129 | 54 |
| Birch veneer MDF: | 109 | 46 |
| MDF: | 87 | 38 |
| MDF with .05" laminate: | 205 | 87 |
| MDF with 1/8" wood edge: | 79 | 33 |
| MDF with 3/4" wood edge: | 90 | 38 |
| MDF with 3/4" x 1 1/2" dropped edge: | 241 | 107 |
Be aware that this is initial sag only. Shelves will sag an additional 50% (1/8") over time with this loading.
Hope this helps someone.
Regards,