Estimating the weight of plywood

TECHNO CAL NOTE N U M BER 260
UNITED STATES DEPARTMENT OF AGRICULTURE FOREST SERVICE
FOREST PRODUCTS LABORATORY
MADISON 5. WISCONSIN Juy1956




ESTIMATING THE WEIGHT OF PLYWOOD I


It is often necessary to estimate the weight of plywood-to-be used, either in the design of a woodenfixture- or structures, or for shpigpup--s Tables of plywood panel weights are difficult to set up 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 estimated 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 necessary for most purposes.

The dry weight of the glue added in making plywood may vary f rom about 15 to 30 pounds per 1,000 square feet of single glue line, but an average value of 2S 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, proportionate 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.




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1. Determine the weight of 1,000 square feet of 1/4-inch Douglas-fir plywood:

Weight of wood: 2 x 345 = 690 lb.
Weight of glue: 2 x 25 = 50
Total 740 lb.

2. Determine the weight of 1,000 square feet of sanded 1/4-inch, 3-ply plywood with a 3/ 16-inch core of yellow-poplar and face and back of Khaya (African mahogany) veneer:

Weight of yellow-poplar: 456 lb.
Weight of Khaya: 1/2 x 320 = 160
Weight of glue: 2 x 25 = 50
Total 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: 8.13 x 243 = 1,976 lb.
Weight of crossbands: 212
Weight of face veneer: 1/3 x 385 = 128
Weight of back veneer: 1/3 x 370 = 123
Weight of glue: 4 x 25 = 100
Total 2,539 lb.




















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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- : 1/10- : 1/8- 3i16. inch inch inch inch
- - - - - - - - - - - -- -- - -

Lb. Lb. Lb. Lb.

HARDWOODS

Ash, black 89 : 286 357 : 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 : 353 : 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 : 111 356 : 445 ; 667
Hackberry 94 302 377 566
Hickory, pecan : 117 : 375 : 469 : 703
Hickory, pignut.. 137 438 548 822
Hickory, shagbark .. 131 419 : 524 : 786
2"
Khaya, (African Mahogany)--: 80 256 320 480
Magnolia, southern 90 : 287 : 358 : 537
Mahogany,Central American- 87 277 347 520
Maple, black : 104 : 332 : 415 : 622
Maple, red : 93 : 297 371 : 556
Maple, silver : 85 : 273 : 348 : 512
Maple, sugar : 113 : 362 : 452 : 678
Oak, northern red : 111 : 354 : 443 : 664
Oak, white : 119 : 380 : 475 : 7 12
Sweetgum : 92 : 296 : 370 : 555
Sycamore : 90 : 289 : 361 : 542


(Sheet I of 2)







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-: 1/10-: 1/8- : 3/16: inch : inch : inch : inch
------------------- ------- ------- -------Lb. Lb. Lb. : Lb.

Tupelo, black 92 : 296 370 : 555
Tupelo, water 88 : 283 : 354 : 531
Walnut, black 96 : 308 : 385 : 578
Willow, black 70 : 224 : 280 : 420
Yellow-poplar : 76 : 243 : 304 : 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 : 350
Redwood 71 : 228 : 285 : 428
Spruce, Sitka : 71 : 226 : 282 : 423


-Weight data are from the Wood Handbook, Agriculture Handbook
No. 72, Washington, D. C., 1955 (t'" -" ""
cated. UNIVERSITY OF FLORIDA
Based on ANC Bulletin No. 19. 111

3 3 1262 9216 6690
-Based on samples from Nicaragua, Bruisn rionauras, a
Cuba.

Z M 108 810 (Sheet 2 of z)