Cold Formed Metal Framing - Bidder De...

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Author Message David G. Axt, CCS, CSI ,SCIP Senior Member Username: david_axt Post Number: 1389 Registered: 03-2002 Posted on Monday, February 16, 2015 - 01:52 pm:    The structural engineer wants to do a bidder design on the exterior cold-formed metal studs. Has anyone written such a section? If so, can you please give me some tips on how to modify MasterSpec? I am not sure why the engineer wants to go with bidder design. The architect, engineer and I will have a conference call tomorrow to discuss the matter. David G. Axt, CCS, CSI, SCIP Specifications Consultant/Web Publisher www.localproductreps.com ken hercenberg Senior Member Username: khercenberg Post Number: 876 Registered: 12-2006 Posted on Monday, February 16, 2015 - 02:53 pm:    Does the engineer mean Delegated Design where the successful Bidder aka the Contractor is responsible for providing engineered shop drawings and related documentation? John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1617 Registered: 03-2002 Posted on Monday, February 16, 2015 - 02:56 pm:    Yes, all the time. It is delegated design, easily accomplished using MasterSpec's Section 054000 Cold-Formed Metal Framing. Unlike other areas of the country, here in New England exterior cold-formed framing is nearly always contractor-designed, so I've done this a lot, for a long time. There is not typically a problem as the contractors have the software to do it. I don't know if the lack of experience with this by contractors in your project area would create problems in bidding because of inexperience (if there is, in fact, a lack of experience). Nevertheless, it should be easily done. Guest (Unregistered Guest) Unregistered guest Posted on Monday, February 16, 2015 - 06:56 pm:    IBC requires registered DP to "review" and submit "deferred submittals" to Building Official; does SE think s/he can shirk the responsibility? IBC also says that such deferred submittals must be specifically pre-identified and pre-approved by Building Official; it shouldn't be a surprise if building official rejects that and requires engineering-design as part of permit approval (see below)? Some building jurisdictions specifically list acceptable deferred submittal items. Calif's DSA recognizes such deferred submittals for portions that just can't be determined at design phase, e.g., elevator support structures, curtainwalls, etc...work that is mostly dependent on specific (successful bidding) manufacturer's product/system and it's specific (reaction) loading criteria. I'm inclined to think that cold-formed framing would not be considered in such a category, especially since AISI has specific (generic) engineering-design criteria/standards for cold-formed framing...and thus might be rejected by building official as qualifying for deferred submittal. Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 709 Registered: 10-2007 Posted on Monday, February 16, 2015 - 09:43 pm:    The fact that the contractor has the "software" is irrelevant unless the contractor is a licensed design professional. What this means is that the contractor will have to hire a registered design professional. What is the motivation for a deferred approval? Did the Architect focus only on the engineers fee not appreciating the fact that the Owner will pay for this fee as part of the construction cost and the Architect will loose the opportunity to coordinate the skin design with the engineer? This is not a skin framing system that needs a specialty engineer to engineer it. If compensation channels are used in the exterior framing the size of the gap may be controlled by the live load deflection of the exterior beams. Has the Architect considered how the building skin will accommodate the drift of the building due to wind or earthquake forces? Assumptions related to this will need to be documented so the contractor's engineer knows what to do. Section 107 of the IBC requires the design professional in responsible charge, ie the prime design professional not the engineer consultant, to review the deferred submittal. The Guest is confusing what the IBC says with California DSA requirements. The nature of the required review is left vague. If you want the project engineer to perform an engineering review of the deferred submittal you will need to pay him. Also note that any changes resulting from this review will likely be the subject of a change order. It may be cheaper to have the SE do the job in the first place. Robert E. Woodburn, AIA, CSI, CCS, CCCA Senior Member Username: bob_woodburn Post Number: 134 Registered: 11-2010 Posted on Monday, February 16, 2015 - 09:59 pm:    This is frequently specified this way (delegated) in the Houston area, so there is at least one structural engineering firm here (there may be two) specializing in CFMF design for contractors and framing subs. They provide the sealed shop drawings and calculations necessary. Like pre-engineered metal buildings, its a niche of structural engineering that may be most efficiently done by a specialist. Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 711 Registered: 10-2007 Posted on Monday, February 16, 2015 - 10:17 pm:    Note that there are two perspectives being presented. Architects saying that the engineering design of the metal stud skin needs to be delegated because a specialist is needed and an SE saying the primary motivation for delegating the design is to minimize the engineers fee. J. Peter Jordan Senior Member Username: jpjordan Post Number: 799 Registered: 05-2004 Posted on Wednesday, February 18, 2015 - 07:39 am:    I typically use a delegated design approach for exterior non-load-bearing cold-formed metal framing. I have only had a couple of projects where the structural engineer wanted to take this on. We have had only one project where this was a problem. The contractor used a drywall contractor who didn't read the spec and assumed that he could use the same stuff he was using on the interior of the building. Did I mention that the wind speed for the project was 120 mph? ken hercenberg Senior Member Username: khercenberg Post Number: 877 Registered: 12-2006 Posted on Wednesday, February 18, 2015 - 08:32 am:    I find it rare on the east coast for the A/E to design the CFMF. On the vast majority of projects I can't even get the structural engineer to look at my Section 054000 let alone write it. On the other hand I've spoken with structural engineers who make a living designing the entire system, sizing every stick on the project, essentially preparing shop drawings for a price. They do not do this as part of the CDs; it's an add service that they are glad to provide. Most framing subs that I've dealt with in the past prefer to be given the load and deflection criteria so they can perform the final design. No matter what, I would always require engineered shop drawings during the submittal process since I have yet to see a Contractor provide exactly what was shown, except in the case of projects where the structural engineer noted above does the layouts. After all, if we can't get the typical structural engineer to design the CFMF the last thing I'm going to want to see is the Architect designing it. Even the ones who can figure out a span table usually can't figure out the lengths of each stick. I can't tell you how many times I've been told to just spec the framing as 6 inches deep by 16 gage for the entire project. Scares the heck out of me. Yep, I'm going to keep requiring sealed, engineered shop drawings even if it's not delegated design. Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 714 Registered: 10-2007 Posted on Wednesday, February 18, 2015 - 12:47 pm:    sealed engineered shop drawings are only needed when the engineer finds it desirable to skip the step of preparing formal design drawings. This happens when the engineer responsible for the delegated design has agreed to also prepare shop drawings. If the design is not delegated there is no need to require sealed engineered shop drawings. I find it interesting that Ken talks about the engineering refusing to be involved with the building skin without mentioning whether such work was in the engineers contracted scope of work. If the exterior skin was excluded from the engineers scope of work why would the Architect expect him to review the specifications for the metal framing? On the other hand if the work was in the engineers scope and he refused to perform it you have another problem. ken hercenberg Senior Member Username: khercenberg Post Number: 878 Registered: 12-2006 Posted on Wednesday, February 18, 2015 - 01:07 pm:    I wonder how many architectural firms really understand the implications of the agreements they sign, both with consultants and with clients. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1618 Registered: 03-2002 Posted on Thursday, February 19, 2015 - 02:11 pm:    Mark, I'm not making the argument that design of cold-formed curtain wall should or should not be done in a particular way. I (and a few others) am just describing the market conditions for the design practice here on the east coast. As Ken points out, structural engineers here would be extremely reluctant to take on this work. I don't know whether it is because of lack of familiarity or fear of not getting enough fee; but they just don't. And yes, this means that the CFMF subcontractor must hire a structural engineer to provide the delegated design submittal; none has ever complained about this (to my employers, anyway). The issue of site observations of work done under such delegated design is an important one. In my last firm, the specs required the same engineer to perform the on-site observations of the installed work. Wayne Yancey Senior Member Username: wayne_yancey Post Number: 717 Registered: 01-2008 Posted on Thursday, February 19, 2015 - 02:17 pm:    Structural engineers in the PNW are also reluctant to design and engineer CFMF, but there are exceptions to the rule depending on the scope and complexity required of the CFMF. Therefore, we delegate the structural engineering to the contractor based in specified performance requirements from the SEs documents, usually the structural general notes. For some reason, 3-part sections from many SEs is a dying art.