TECHNICAL NOTE number 260 UNITED STATES DEPARTMENT OF AGRICULTURE FOREST PRODUCTS LABORATORY MADISON 5. WISCONSIN ESTIMATING THE WEIGHT FOREST SERVICE It is oftennecessary to estimate the weight of in the design of a wooden fixture or structures, or tor snipping purpc Tables of plywood panel weights are difficult to setup because of the pos- sible variations in panel constructions, in veneer thicknesses, and in species, and because of the varying number of glue lines that may be present. The weight of plywood panels, however, can readily be esti- mated by summing up the weights of the various plies of wood, the glue, and the water in the wood. The weights of several thicknesses of veneers of various species are given in table 1, in pounds per 1,000 square feet of surface. These weights were calculated on the assumption that the moisture content of the wood was 8 percent. Weight adjustments can be made if the moisture content is not reasonably near 8 percent, but this refinement is not nec- essary for most purposes. The dry weight of the glue added in making plywood may vary from about 15 to 30 pounds per 1,000 square feet of single glue line, but an average value of 25 pounds may be assumed here. In 3 -ply panels with 2 glue lines, the weight to be used in the calculation is therefore 50 pounds, while in 5-ply panels it is 100 pounds, and so forth. For thicknesses of veneer or lumber cores not shownin table 1, propor- tionate values can be calculatedby using the figure for 1/10-inch veneer as a basis weight. For example, a lumber core with a thickness of 13/16 inch, or 0.813 inch, would have a weight 8.13 times that of 1/10-inch veneer of the same species. The following are some sample calculations of plywood panel weights as calculated from veneer weights given in table 1. 1- 1. Determine the weight of 1,000 square feet of 1/4-inch Douglas-fir plywood: Weight of wood: 2 x 345 = Weight of glue: 2 x 25 = Total 690 lb. 50 740 lb. 2. Determine the weight of 1,000 square feet of sanded 1/4-inch, 3-ply ply wood with a 3 / 16-inch core of yellow-poplar and face and back of Khaya (African mahogany) veneer: Weight of yellow-poplar: Weight of Khaya: 1/2 x 320 = Weight of glue: 2 x 25 = Total 456 lb. 160 50 666 lb. 3. Determine the weight of 1,000 square feet of sanded 1-inch, 5-ply lumber core paneling, with a 13 / 16 -inch (0.813-inch) yellow- poplar core, 2 crossbands of 1/20-inch basswood veneer, a 1/24-inch face of walnut veneer, and a 1/24-inch back of sweetgum veneer: Weight of lumber core: Weight of crossbands: Weight of face veneer: Weight of back veneer: Weight of glue: Total 8.13 x 243 = 1/3 x 385 = 1/3 x 370 = 4 x 25 = 1,976 lb. 212 128 123 100 2,539 lb. Table 1. --Weight of 1,000 square feet of veneer, based on weight and volume at a moisture content of 8 percent 1 Species - Thickness of veneer 1/32- inch : 1/10- • inch 1/8- : inch : 3/ lb- inch Lb. : Lb. Lb. : Lb. HARDWOODS Ash, black : 89 : 286 : 3 57 : 536 Ash, white : 108 : 346 : 432 : 648 Basswood, American : 66 : 212 : 266 : 398 Beech, American : 112 : 360 : 450 : 675 Birch, sweet : 120 : 383 : 479 : 719 Birch, yellow : 110 : 3 53 : 442 : 662 Butternut : 69 : 220 : 275 : 412 Cherry, black : 91 : 290 : 362 : 544 Cottonwood, black : 62 : 198 : 248 : 372 Cottonwood, eastern : 73 : 233 : 292 : 437 Elm, American : 92 : 296 : 370 : 555 Elm, rock : HI : 3 56 : 445 : 667 Hackber ry 94 302 377 566 Hickory, pecan 117 375 469 703 Hickory, pignut 137 438 548 822 Hickory, shagbark Khaya, (African Mahogany)— 131 419 524 786 80 256 320 480 Magnolia, southern Mahogany, Central American— 90 287 358 537 87 277 547 520 Maple, black 104 : 332 : 415 : Maple, red 93 : 297 : 371 : 556 Maple, silver : 85 : 273 : »48 : 512 Maple, sugar : 113 : 362 : 452 : 678 Oak, northern red : 111 : 354 : 443 : Oak, white : 119 : 380 : •175 : 7 1 . Sweetgum 92 : 296 : 370 : Sycamore : 90 : 289 : 361 (Sh< tt : Table 1. -- Weight of 1,000 square feet of veneer, based on weight and volume at a moisture content of 8 percent (Continued) 1 Species - Thickness of veneer > 1/32- inch 1/10- inch 1/8- inch 3/16- inch Tupelo, black Tupelo, water Walnut, black Willow, black Yellow-poplar Lb. 92 88 96 70 76 Lb. 296 283 308 224 243 Lb. 370 3 54 385 280 304 Lb. 555 531 578 420 456 SOFTWOODS Douglas-fir (coast type) : 86 : 276 : 345 : 517 Fir, noble : 68 : 218 : 273 : 409 Fir, pacific silver : 71 : 227 : 284 : 427 Hemlock, western : 75 : 239 : 299 : 448 Larch, western : 99 : 318 : 379 : 597 Pine, ponderosa : 72 : 229 : 286 : 430 Pine, sugar : 65 : 207 : 259 ■ 389 Pine, western white : 71 : 226 : 282 . 423 Redcedar, western 58 187 233 3 50 Redwood 71 2 28 285 : 428 Spruce, Sitka 71 226 282 : 423 —Weight data are from the Wood Handbook, Agriculture Handbook No. 72, Washington, D. C. , 1955 (t * ' " v cated UNIVERSITY OF FLORIDA 2 ~~Based on ANC Bulletin No. 19. 3 3 1262 09216 6890 —Based on samples from Nicaragua, Britisn nonauras, ana Cuba. Z M 108 810 (Sheet 2 of 2)