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Re: SIP Spec

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Eric:

I have no issue with the SIPA report.  To me, it is just as valid as an ICC-ES report.

My point regarding the two reports is that not all code officials will think as I do.  There will be some code officials that believe that an ICC-ES report is the only way to satisfy the "alternative materials" provision...and may not permit the use of SIPs that have an NTA report.  The fact that this is wrong on their part will have little impact on the reality of the situation.  You might be able to ultimate prevail with a NTA report over a code official, but it likely will be a lot of work and it might be a situation of "winning the battle, but losing the war".

My other point was that the NTA Design Guide alone is not enough.  Neither are just structural properties of components.  The reality is that SIPs are not just components...they are a product made of those components that must be assembled in a proper way to achieve the desired result.  Thus, just having components that meet some structural properties is not enough.  There also has to be some process in place that makes sure those components are assembled in manner that achieves the expected performance of the composite material.  For any SIP manufacturer that has a "code report" (whether through ICC-ES or I would assume NTA), this would be a part of the code/evaluation report process.  If a SIP manufacturer does not have a "code report", then simply using the Design Guide for their SIPs, even if the SIPs have quality components, would not be enough...there would also need to be some process (presumably by a third party) that ensures that SIP manufacturer is maintaining quality manufacturing of their SIPs.  To go back to my concrete analogy, the fact that I might specify 3000 psi concrete on my documents and reference that aggregates, cement, etc all need to meet certain ASTM requirements will not ensure that I will actually get quality, 3000 psi concrete...that is why we also require cylinder tests and such.  The same is true of SIPs.  Just because the OSB has the required allowable stresses or elastic modulus or the foam core has the required shear modulus does not mean that the final finished SIP will perform as expected.  Those components still need to be put together in a proper, quality manner that is consistent so that they will effectively work together to achieve the expected performance of the composite material.

As to the ICC-ES permitting an "engineering option", yes, you are technically correct.  From practical experience, it is not as black and white as that.  You are at the mercy of what they will accept, which in my experience is not much.

While I tentatively believe that NTA's approach to "code reports" for SIPs is better than ICC-ES' approach, I still believe that the SIP industry needs to move toward getting a rational engineering analysis and design method in the codes...and leave behind the whole "evaluation report" for outlining load capacity and deflection and other structural behavior.  There will still be a market for some sort of third party evaluation of the manufacturing process to ensure that the SIPs are being properly manufactured by a particular manufacturer to achieve what the code would expect to be the behavior of the composite SIP product when made of the code specified minimum materials.

Regards,

Scott

On Mar 22, 2010, at 9:43 AM, Eric Tompos wrote:

> Scott:
> 
> In terms of specification, the SIPA report departs from the ICC-ES model
> of qualification in that the panels are "performance rated," similar to
> structural sheathing or performance rated wood I-joists.  The values in
> Table 1 of the report are all that needs to be known to specified or
> classify the structural performance of the panel.  In other words, an
> engineer could design using the values in Table 1 (or other values), and
> simply specify these values in the design documents.  However, at this
> point in time, few people would understand the meaning of the
> performance values.
> 
> Currently only one "grade" of panel exists. But in the future, it is
> very likely that multiple grades will exist.  At this point the limits
> of use in the design guide are obvious--no other SIP manufacturer
> specifies SIPs in this manner.  But this will change, I am currently
> working with other SIP mfg's on establishing similar engineering data.
> Whether this information will end up in ICC-ES reports is yet to be
> seen.  ICC-ES AC04 does permit an "engineering" option in lieu of just
> providing test data.
> 
> With respect to quality assurance, the engineering approach permits
> pooling of all the test data--this wasn't possible before.  Using the
> pooled data, true statistical confidence intervals can be established,
> which permits the use of statistical process control in the production
> facility.
> 
> --Eric
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