Direct withdrawal and head pull-through performance of nails and staples in structural wood-based panel materials.

In both the nail and staple direct withdrawal resistance tests, l/2-inch thick waferboard and two OSBs performed equal to or better than CD-grade plywood sheathing in all three exposures, but the veneered composites performed as well as plywood only in the dry and 24hour soaked conditions. The ASTM 24-hour soaking and 6-cycle accelerated-aging exposures reduced the average nail withdrawal resistance value in roof sheathing specimens about 30 and 40 percent, respectively; and reduced the staple withdrawal resistance about 55 and 8 percent, respectively. The staples showed higher withdrawal resistance values than the nails in the dry and 24-hour water-soaked conditions, while nails showed much better results in the 6-cycle accelerated-aged condition. The nailhead pull-through and staple-crown pullthrough resistance tests yielded similar average values in all wood-based materials (except the l/2-in. thick waferboard) in all exposure conditions. The difference between the ASTM nailhead pull-through and nailhead push-through are relatively small in all exposure conditions. The newly developed nailhead push-through test appears to be a good substitution for the ASTM nailhead pull-through method. The average values of nail and staple withdrawal and pull-through resistance of most of the nine wood-base materials tested meet the minimum requirement of various specifications or current standards. An average home takes as many as 70,000 nails, which require about 300,000 hammer blows to drive them in place. For efficiency, the use of power-driven staples for the fastening of wood materials has increased in recent years (14). In addition, some new types of wood-based panels, which have a density or hardness similar to some dense hardwood lumbers, can pose greater hammer-driven nailing problems than those encountered in the use of softwood plywood panels. To overcome this difficulty, a widespread adaptation of a proper power-driven fastening system may be the possible solution. New information on the performance of staples in these new sheathing and siding products is needed for comparative purposes (10). Direct withdrawal resistance of nails and staples is the force required to pull imbedded fasteners from the wood. The holding power of fasteners is especially important when applying shingles or siding materials to roof or wall sheathing (14). A standard ASTM nailhead pull-through test has been used to determine the resistance of a wood material by pulling the head of a nail through the thickness of the specimen (2,3). This test is meant to simulate the conditions encountered when wind or earthquake forces pull sheathing or siding from a wall. It was reported that the problem of maintaining a firm grip on the nail shank has frequently been encountered in the course of nailhead pull-through using the method described in ASTM D 1037. The nail-slip problems encountered in the use The authors are, respectively, Professor of Wood Science, Dept. of Forestry, 110 Mumford Hall, 1301 West Gregory Dr., Univ. of Illinois, Urbana, IL 61801; Research Technologist, USDA Forest Serv. , Forest Prod. Lab. , One Gifford Pinchot Dr., Madison, WI 53705; Former Research Assistant, Dept. of Forestry, Univ. of Illinois; and Associate Professor of Biometrics, Dept. of Forestry, Univ. of Illinois. This study was supported by the USDA Forest Products Lab. , Madison, WI and the Dept. of Forestry, Illinois Agri. Expt. Sta. , Univ. of Illinois. Published as Special Issue No. 87-1 of the Forestry Research Rept. , Dept. of Forestry, on research conducted under USDA Forest Serv. Coop. Agreement No. FP-84-626. Parts of this study were presented at the 1986 FPRS Annual Meeting in Spokane, WA. This paper was received for publication in August 1987. © Forest Products Research Society 1988. Forest Prod. J. 38(6):19-25. FOREST PRODUCTS JOURNAL Vol. 38, No. 6 19 of the present standard test often lead to unreliable test results (5). Table 1 lists the existing direct nail withdrawal and nailhead pull-through performance standard for some panel products. Previous study determined the effects of test methods and accelerated aging on lateral fastener resistance in wood-based products (6). However, little information is available on the fastener direct withdrawal and head pull-through resistance performance of new structural wood-based sheathing panels. The objectives of this study were to: 1) develop data on the maximum direct nail and staple withdrawal, and the pull-through performance of nine commercial structural wood-based sheathing and siding panels compared to conventional plywood sheathing material; and 2) determine the effects of severe exposure on the nail and staple performance by conducting accelerated-aging tests. Experimental design and method