b'THE OFFICIAL NFBA MAGAZINEcontinued from page: 295. With problem endlaps, the endlap fasteners often are observed to be backing out. Butyl endlap sealant tape is commonly omitted at panel endlaps in post-frame structures. Water and dirt siphon upslope between the endlap panels, creating a visible stain and dirt line. If the moisture reaches the shank of the endlap fasteners between the panels, it enters the building, causing the wood around the RESEARCH & TECHNOLOGYfastener shank to become wet and weakened, and this moisture eventually causes the wood to deteriorate. This moisture issue reduces the endlap fasteners structural capacity, promoting fastener backout. Butyl endlap sealant tape needs to be installed in panel endlaps. We cant just worry about handling the forces involved with the endlapwe must keep the endlap dry.6.1" long roof panel fasteners have fewer issues than 1" long roof panel screws in larger structures. Larger diameter screws also have fewer issues. Increasing the number of fasteners at and around the panel endlap has been helpful in more effectively handling the forces at the panel endlap. It is common to use the double fastener endlap pattern not just at the panel endlap, but also at least in the adjacent upslope and downslope purlins. Panel endlaps and adjacent purlins that utilize the beefed up double fastener pattern have fewer issues, particularly in two-piece roof applications (i.e., only one panel endlap in an eave to ridge panel run).7.Fasteners applied to the top of roofing panel ribs have fewer issues than fasteners applied through the flat of the panel. Fasteners applied to the top of the panel ribs effectively create a gap between the fastener/panel intersection point and the wood purlin underneathtypically this gap is " or the height of the panel rib. This gap allows the fastener shank to flex to some degree without damaging the wood purlin or the panel. However, there is a limit to how much movement can be handled with this connection design.8.Southern Yellow Pine (SYP) purlins have an open cell structure vs. Spruce-Pine-Fir (SPF) purlins. Fasteners tend to back out of SYP much easier than SPF due to SYPs open cell structure allowing moisture to move quickly and frequently in and out of the wood. These wood purlin moisture content changes encourage fastener backout.9.The south side of a structure has more endlap issues than the north side. Those slopes that see the sun first warm up faster each day. The faster the temperature rises, the faster the roof panels expand. This rate of expansion makes a difference and causes more issues than slower rates of expansion and contraction. Expansion and contraction related endlap issues are not just from the annual changes in temperature but are also from the continued on page: 31ASC MACHINE TOOLS, INC. PREMIUM QUALITY ROLLFORMING MACHINERYPANEL LINES TRIM LINES CZ PURLIN LINES PURLIN STACKER TRACK LINES ROLL UP DOOR LINESVISIT US ATSLITTING LINES COIL UPENDER DECKING LINES CHANNEL LINES SEAMING STATIONS ROLL-UP STATIONS BOOTH 521MANUFACTURED IN SPOKANE, WA SINCE 1949 WWW.ASCMT.COMTEL: (509) 534-660030 / FRAME BUILDER - VOL5 1'