SDS screws edge and end distances
SDS screws edge and end distances
(OP)
Just wondering if it is ever acceptable to relax on the ICC report's very large end distance - 4" in all load directions for a 1/4" SDS screw vs NDS 4D to 7D for "dowel type fasteners".
I ask because it seems common for engineers and contractors to use structural wood screws all over the place with little regard for ICC end/edge distances. Specifically I am reviewing a calc from a wood-specialist engineer providing some of the timber connection details on a project we are doing and he doesn't seem to pay attention to ICC reported end distances. Is there a reason the ICC reports don't use NDS equations?
Thanks,
Aaron
I ask because it seems common for engineers and contractors to use structural wood screws all over the place with little regard for ICC end/edge distances. Specifically I am reviewing a calc from a wood-specialist engineer providing some of the timber connection details on a project we are doing and he doesn't seem to pay attention to ICC reported end distances. Is there a reason the ICC reports don't use NDS equations?
Thanks,
Aaron






RE: SDS screws edge and end distances
RE: SDS screws edge and end distances
http://www.icc-es.org/reports/pdf_files/esr-2236.p...
RE: SDS screws edge and end distances
in cases where you need to apply fasteners to situations that dont fall within published, well defined, clear cut design guides, use your engineering judgement.
RE: SDS screws edge and end distances
RE: SDS screws edge and end distances
RE: SDS screws edge and end distances
Based upon glance at ESR provided and NDS footnotes, it appears that the SDS steel quality is substantially elevated above the NDS. If that is the case, (I hope someone checks me) I can imagine that several of those 6 yield equations have been rendered moot such that now, with the SDS screw, the wood itself governs. Hence bigger distances for bigger allowables.
Does the manufacturer have some comfort factor in those end/edge/space distances? I am sure they do, and also that their analysis equations did not come out as exactly 4.00000 inches.
Would I use different edge/end/space distances than the ESR report? Almost for sure not, unless I ran the 6 limit equations in the NDS.
Thanks for bringing this item to the forum as I had not noticed it before.
RE: SDS screws edge and end distances
As wannabeSE said, start there...
Mike McCann, PE, SE (WA)
RE: SDS screws edge and end distances
From what I heard, I understand that:
1. Simpson's values and distances are conservative compared to the NDS. They are for untested applications. Their primary focus on the larger distances is to avoid splitting of the wood.
2. Other Simpson connectors in the catalog use SDS screws with smaller distances, but they are rated and tested applications.
3. If you want to use distances smaller than the Simpson values, revert to calculating the values using the NDS Tables and the appropriate reduction factors.
Seemed to be a reasonable approach to me...
Mike McCann, PE, SE (WA)
RE: SDS screws edge and end distances
If you want to use Simpson values, use Simpson dimensions (and applications).
If you want to use NDS dimensions, use NDS values?
RE: SDS screws edge and end distances
I am going to call again though, as it seems to me that the NDS factors would still need to be applied to the Simpson values.
I will post back later.
Mike McCann, PE, SE (WA)