Here is the perplexing requirement worth blogging and coming to a consensus on:
Section 1705.3 requires SI of the "seismic-force-resisting systems..." (Section 1705.31).
This boggles Chuck and me. If one was able to clearly delineate out the SFRS in the overall Bearing Wall System, only a few sticks would be left, in my opinion, that are used for gravity only and, subsequently, need not be checked. We would be asking the special inspector to spend 2 days on the house checking every nail that resides as a component of the SFRS, for shearwalls, diaphragms, etc.
Chuck suggested that perhaps only the exceptions triggering the SI of the SFRS (along with any other important components) be specified for SI. That seems logical to me. Perhaps we could substantiate this preference or "interpretation" by alluding to the fact that the phrase "seismic-force-resisting systems" from section 1705.31 is plural and only certain seismic force resisting systems, or "components", require inspection.
Thoughts?
2 comments:
I would point out that there is no specific description of what constitutes a special inspection of a SFRS. The walls of a concrete, masonry, or steel frame structure would almost invariably need inspection anyway, so that leaves us with CFS and wood shear walls.
The requirement does not specify the inspection type (periodic vs. continuous). Therefore, it may be assumed that the type of inspection is up to the Engineer of Record.
For a standard residential structure, I would recommend that the inspection be limited as you described, with the additional limitation of using a sampling method, rather than inspecting every item within even the discontinuous areas. If a randomly selected 20% of the nails are correctly placed and no visible oddities are there, the likelihood is that the remainder of the portion of the structure is also sound.
If, on the other hand, you have a very high load wall - say, a wall with double sided 5/8" sheathing, 10d (or 12d) @ 2" o.c. staggered, and 4x studs - you may very well want to verify every little detail.
I would also recommend verifying all critical (5000 lb or more) tiedown installations. I've run into far too many structures where they substitute (2) 2x for a 4x or even 6x post.
Limiting the scope of the SI to the portions of the structure that fall outside the conventional construction provisions would seem to be in the spirit of 1704.1.1 Exception #1. Additionally 2308.1.1 allows us to provide engineering for portions that do not conform to the prescriptive approach. Therefore it would stand to reason that the SI could be limited to a portion as well.
I personally do not approach my designs using section 2308 straight out of the gates though. In most cases I find it quicker to just engineer the entire structure rather than having to filter through the prescriptive sections of 2308, (braced wall lines, alternate, etc.).
Therefore, where the project allows (i.e., wood framing), I suggest that we attempt to comply with 1704.1.1 and section 1705 by requiring SI/structural observation by our firm. We can perform SI with the approval of the building official, and I have never had one say "no".
There seems to be a few advantages to this approach. First, we may be able to be a little looser with the development of the statement of special inspections. Second, I have found that both the field inspectors and plan reviewers like it when we make more of a presence at the site. Third, both Ann and I are not impressed with the WABO approved wood framing special inspectors in our area. Therefore inspections by us should increase the quality of the inspection.
I know that there has been some discussion relating to liability exposure with SI although it is my understanding that Charlie does not feel that this is something to be concerned with any more.
Notes section 1008 "contractors Responsibility" does mention the "statement of special inspections" although we have not yet developed this notes section (as a starting point). Anyone feel like we should develop a base section of notes or should we just alter S1.1 for the additional direction relating to the SI?
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