AaronMcD
Structural
- Aug 20, 2010
- 273
Just wondering what you all do when you use structural composite lumber (LVL, LSL, PSL, etc.)
There is a Simpson technical bulletin, as well as a similar sheet by Boise Cascade, and a link to the bulletin on Trus Joist. The bulletin lists reduction factors for various connectors installed on narrow face of PSL, LVL, and LSL. Included is a not that straps are not permitted.
The ESR reports for Boise Cascade and Trus-Joist products list 3" minimum nail spacing for 8d and 10d for typical stud and rafter thicknesses (with max. 2 staggered rows), which is greater than typical nail spacing per row on metal straps.
I think it is very common to use coil straps, fixed length straps, twist straps, H2A, etc. for collectors, truss and rafter ties. Is this something we should be avoiding? If so, it seems SCL would not be useful on any projects, since I can't think of any project that doesn't use straps for collectors, and probably some sort of metal connector for rafter hold down and out of plane wall loading. Then of course there are vertical straps at exterior walls of multistory wood buildings.
What about twist straps where holes tend to be staggered more than straight straps? Even with the stagger, the end distance of twist straps used as hurricane ties is less than required by ESR reports, and the nail patterns use more nails than 1.5" O.C. (equivalent to 3" rows staggered).
Perhaps for coil straps one could specify using every other hole and make strap end lengths twice as long, but this still doesn't solve the issue for fixed length twist straps and hurricane ties.
There is a Simpson technical bulletin, as well as a similar sheet by Boise Cascade, and a link to the bulletin on Trus Joist. The bulletin lists reduction factors for various connectors installed on narrow face of PSL, LVL, and LSL. Included is a not that straps are not permitted.
The ESR reports for Boise Cascade and Trus-Joist products list 3" minimum nail spacing for 8d and 10d for typical stud and rafter thicknesses (with max. 2 staggered rows), which is greater than typical nail spacing per row on metal straps.
I think it is very common to use coil straps, fixed length straps, twist straps, H2A, etc. for collectors, truss and rafter ties. Is this something we should be avoiding? If so, it seems SCL would not be useful on any projects, since I can't think of any project that doesn't use straps for collectors, and probably some sort of metal connector for rafter hold down and out of plane wall loading. Then of course there are vertical straps at exterior walls of multistory wood buildings.
What about twist straps where holes tend to be staggered more than straight straps? Even with the stagger, the end distance of twist straps used as hurricane ties is less than required by ESR reports, and the nail patterns use more nails than 1.5" O.C. (equivalent to 3" rows staggered).
Perhaps for coil straps one could specify using every other hole and make strap end lengths twice as long, but this still doesn't solve the issue for fixed length twist straps and hurricane ties.
