Non-Structural Metal Framing

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Author Message J Potter (Unregistered Guest) Unregistered guest Posted on Friday, January 19, 2018 - 02:06 pm:    When is it appropriate to use a 30 mil (20 gauge) drywall stud vs. a 33 mil (20 gauge) structural stud. In my firm's section for Non-Structural Metal Framing, 33 mil is currently called out. However, I have been told that 30 mil is more industry standard. I can't seem to find a reason why we specify 33 mil and not 30 mil studs. Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 360 Registered: 10-2003 Posted on Friday, January 19, 2018 - 02:23 pm:    I do not have an answer to your question, but want to advocate in favor of "gage" instead of "gauge". Michael Chusid, RA FCSI CCS 1-818-219-4937 www.chusid.com www.buildingproduct.guru Lynn Javoroski FCSI CCS LEED® AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 2135 Registered: 07-2002 Posted on Friday, January 19, 2018 - 02:42 pm:    J Potter, who said the 30 mil is "industry standard"? ken hercenberg Senior Member Username: khercenberg Post Number: 1144 Registered: 12-2006 Posted on Friday, January 19, 2018 - 02:46 pm:    30 mil is considered a "drywall stud" while 33 mil is typically considered CFMF (Section 054000). Of course if you permit EQ studs, it's all academic. Brian Payne, AIA Senior Member Username: brian_payne Post Number: 123 Registered: 01-2014 Posted on Friday, January 19, 2018 - 02:50 pm:    Begin can of worms: Do you want a prescriptive approach or performance? We use a performance approach which sets the minimum deflection, maximum spacing and stud depth, but leaves the actual spacing and gage to the delegated design professional. Some firms set a minimum gage based on pullout concerns for attaching equipment. Gage is becoming more of a reference than anything due to the prevalence of equivalent studs. J Potter (Unregistered Guest) Unregistered guest Posted on Friday, January 19, 2018 - 02:46 pm:    It was an industry rep ... I typed it up wrong, the industry standard for a 20 GAGE stud is 30 mils, but I believe the industry standard is really like 25 GAGE? Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 838 Registered: 10-2007 Posted on Friday, January 19, 2018 - 04:10 pm:    Given that 20 gage members may have either a 30 or 33 mil thickness I would suggest abandoning the use of gages and specify metal studs based on the actual thickness. ken hercenberg Senior Member Username: khercenberg Post Number: 1145 Registered: 12-2006 Posted on Friday, January 19, 2018 - 04:20 pm:    Exactly what Mark said. As to delegated design, my understanding was that CFMF can be delegated design. Drywall studs are usually sized by the AOR. There is no hard and fast rule; you might be push-back from the contractor when specifying delegated design for drywall studs but they still have to do it if they signed the contract. Regarding 20 vs. 25, it depends on your project type, application, and needs. Best if you specify mil thickness as this has been the real industry standard for years. There is no "industry standard" that I know of regarding 20 vs. 25 gage. I'd beware of your product rep. As Brian points out, be aware of all your options including whether or not your firm or your client is okay with EQ studs. Some people love them, some hate them, and some permit them in some cases and not others. Steven Bruneel, AIA, CSI-CDT, LEED-AP, EDAC Senior Member Username: redseca2 Post Number: 626 Registered: 12-2006 Posted on Friday, January 19, 2018 - 04:55 pm:    Unfortunately, gage is the universal spoken term of site meetings, value engineering fun-fests, RFI's, truck hood sketch ups and every other discussion involving cold-formed metal for construction, except perhaps engineering calculations. So we include a metal thickness versus "Gage" table in our DIV 05 and DIV 09 metal stud sections in the "Quality Assurance" article. You can find similar charts in Steel Stud Manufacturers Association (SSMA) publications. Usually these include Minimum thickness in Mils, Minimum thickness in inches, Minimum thickness with galvanized coating and "for Reference Only", Gage. anon (Unregistered Guest) Unregistered guest Posted on Friday, January 19, 2018 - 04:38 pm:    Both non-structural metal framing and cold-formed metal framing spec sections can be delegated design (the former for 5lb/sf mech load as required by code). It is impossible to establish the minimum "gage" thickness of any stud without also factoring in the ksi steel strength, something that this thread has not addressed. Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 839 Registered: 10-2007 Posted on Saturday, January 20, 2018 - 04:17 am:    While many individuals refer to gage the standards talk in terms of thickness. This problem is complicated by the reluctance of Architects to involve the project structural engineer in the design of these elements and instead attempt to delegate the design to the contractor. Brian Payne, AIA Senior Member Username: brian_payne Post Number: 124 Registered: 01-2014 Posted on Saturday, January 20, 2018 - 07:36 am:    Mark, I’ve never worked with a structural engineer that wanted to mess with interior non structural framing. I have always used DD with interior framing and haven’t run into any issues. I don’t object to getting input from structural, but I don’t see the risk of not especially when structural explicitly excludes it from third scope. J. Peter Jordan Senior Member Username: jpjordan Post Number: 1014 Registered: 05-2004 Posted on Saturday, January 20, 2018 - 08:07 am:    Generally, the scope of work for a structural consultant will include "structural" elements as defined by ASCE. It is worth taking a look at. The architect may want to modify this to include other elements as well. I worked on a project a number of years ago where the architect assumed that carport covers were going to be addressed by structural so they told me to not include a protective cover section. The "hole" was not discovered until construction started. Most structural engineers will provide design services for stuff that it not strictly within their scope, but they need to be asked. I have used delegated design for items such as cold-formed metal framing (exterior framing) and protective covers without any problem for many years. There was one project where the interior stud sub (probably a drywall contractor) had the exterior studs included in his scope. Since the project was subject to hurricane winds, the exterior studs were more critical than usual. To complicate things, there were some conflicts between architectural and structural Drawings. We got it done, but there was much weeping, wailing, and gnashing of teeth. J. Peter Jordan, FCSI, AIA, CCS, LEED AP, SCIP Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 840 Registered: 10-2007 Posted on Saturday, January 20, 2018 - 02:02 pm:    A major reason engineers exclude the "non-structural elements" is because of pressure to reduce the design fees. So the solution is to exclude certain scopes of work with the intent that the design fees are buried in the contractors fee. Bait and switch. In my experience delegating steel connection design to the fabricator can result in higher overall engineering costs and can have a negative impact on project schedule. In general structural engineers will do non-structural framing if they will be paid for the work. Also if the structural engineer is to do the non-structural framing he would need the relevant architectural drawings completed early enough that he has time to do his work. Yes engineers will do work not within their scope but they should be paid. Too often these requests assume the work is for free. Yes there are some situations where interior framing may not require formal engineering but there are a number of situations where because of creative design elements there are real structural issues. It might be nice if the Architect were aware of these issues so that they could be proactively resolved.. In my experience the structural engineer's scope of work is developed in the context of either a ACEC-CASE document or in California the SEAOC Guidelines. In either situation the intent of these documents is to help the engineer and the client negotiate a scope. Please provide the name of the ASCE document being referred to. anon (Unregistered Guest) Unregistered guest Posted on Monday, January 22, 2018 - 12:48 pm:    We had a problem on one project in which the structural engineer refused to design certain elements in the project just "because." There literally was no other reason given. Their own specification section 051200 Structural Steel Framing had this under the Definitions Article (as does every MasterSpec section out of the box): A. Structural Steel: Elements of the structural frame indicated on Drawings and as described in AISC 303, "Code of Standard Practice for Steel Buildings and Bridges." AISC 303 States the following: 2.1. Definition of Structural Steel Structural steel shall consist of the elements of the structural frame that are shown and sized in the structural design documents, essential to support the design loads and described as: Anchor rods that will receive structural steel. Base plates, if part of the structural steel frame. Beams, including built-up beams, if made from standard structural shapes and/or plates. Bearing plates, if part of the structural steel frame. Bearings of steel for girders, trusses or bridges. Bracing, if permanent. Canopy framing, if made from standard structural shapes and/or plates. Columns, including built-up columns, if made from standard structural shapes and/ or plates. Connection materials for framing structural steel to structural steel. Crane stops, if made from standard structural shapes and/or plates. Door frames, if made from standard structural shapes and/or plates and if part of the structural steel frame. Edge angles and plates, if attached to the structural steel frame or steel (open-web) joists. Embedded structural steel parts, other than bearing plates, that will receive structural steel. Expansion joints, if attached to the structural steel frame. Fasteners for connecting structural steel items: permanent shop bolts, nuts and washers; shop bolts, nuts and washers for shipment; field bolts, nuts and washers for permanent connections; and, permanent pins. Floor-opening frames, if made from standard structural shapes and/or plates and attached to the structural steel frame or steel (open-web) joists. Floor plates (checkered or plain), if attached to the structural steel frame. Girders, including built-up girders, if made from standard structural shapes and/or plates. Girts, if made from standard structural shapes. Grillage beams and girders. Hangers, if made from standard structural shapes, plates and/or rods and framing structural steel to structural steel. Leveling nuts and washers. Leveling plates. Leveling screws. Lintels, if attached to the structural steel frame. Marquee framing, if made from standard structural shapes and/or plates. Machinery supports, if made from standard structural shapes and/or plates and attached to the structural steel frame. Monorail elements, if made from standard structural shapes and/or plates and attached to the structural steel frame. Code of Standard Practice for Steel Buildings and Bridges, June 15, 2016 AMERICAN INSTITUTE OF STEEL CONSTRUCTION 16.3-6 CLASSIFICATION OF MATERIALS Posts, if part of the structural steel frame. Purlins, if made from standard structural shapes. Relieving angles, if attached to the structural steel frame. Roof-opening frames, if made from standard structural shapes and/or plates and attached to the structural steel frame or steel (open-web) joists. Roof-screen support frames, if made from standard structural shapes. Sag rods, if part of the structural steel frame and connecting structural steel to structural steel. Shear stud connectors, if specified to be shop attached. Shims, if permanent. Struts, if permanent and part of the structural steel frame. Tie rods, if part of the structural steel frame. Trusses, if made from standard structural shapes and/or built-up members. Wall-opening frames, if made from standard structural shapes and/or plates and attached to the structural steel frame. Wedges, if permanent. I have recommended/suggested that our consultant agreement include this requirement to establish a minimum scope, thereby avoiding arguments with structural engineers on future projects. Steven Bruneel, AIA, CSI-CDT, LEED-AP, EDAC Senior Member Username: redseca2 Post Number: 628 Registered: 12-2006 Posted on Monday, January 22, 2018 - 02:46 pm:    The bottom line is what ends up being shown on the structural drawings versus the architectural drawings. We carry structural steel in our architect provided 05 50 00 - Metal Fabrications to cover these. Some recent examples include: The SEOR designs and documents the roof equipment screen frames, but leaves out a horizontal member needed for the cladding and shows a swing door opening but not the TS frame for the swing door. The SEOR designs and documents the framing for an elevator shaft and the guide rail supports, but doesn't include the continuous vertical TS that the manufacturer's guide rail needs to anchor to. A great deal of our work is California Health Care permitted through the (California) Office of Statewide Health Planning and Development (OSHPD). For these projects, the SEOR is contracted to provide engineered solutions and calculations for non-structural metal framing when required conditions are not covered in the standard details provided or referenced by OSHPD. For these instances, the SEOR sketches them up and they are shown on the Architectural drawings John Hunter Senior Member Username: johnhunter Post Number: 159 Registered: 12-2005 Posted on Monday, January 22, 2018 - 04:48 pm:    To return to the original question, we generally call for studs as requried by loads, but not less than 30 mils for interior non-structural partitions. TCNA requires 33 mil studs for partitions supporting tile, so we often have both 30 and 33 mil studs on the same project. Also up to 30 mils self-drilling screws are used and at 33 and thicker self-tapping are required. We often engage an engineer to design the non-structural framing. Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 362 Registered: 10-2003 Posted on Tuesday, January 23, 2018 - 12:07 am:    Steven -- What is "TS"? Michael Chusid, RA FCSI CCS 1-818-219-4937 www.chusid.com www.buildingproduct.guru Ronald L. Geren, FCSI, AIA, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 1489 Registered: 03-2003 Posted on Tuesday, January 23, 2018 - 12:49 am:    Probably "tube steel" Ron Geren, FCSI, AIA, CCS, CCCA, SCIP www.specsandcodes.com Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 841 Registered: 10-2007 Posted on Tuesday, January 23, 2018 - 02:20 pm:    The problem with AISC definition of structural steel is that it excludes many steel elements that are a part of the primary structural system. This definition is intended to define scope of work of the fabricators but specifications should not do this. This is in the AISC standard to appease the Fabricator members who really control AISC. My practice is to make it clear in the structural steel specification section that it applies to all steel fabrications shown on the structural drawings. Note that the AISC definition of structural steel excludes steel stairs even if they are custom stairs shown on the structural drawings. You do not have to go along with the AISC definition of structural steel. Metal fabrication and structural steel specifications need to be coordinated since it is not uncommon for items in the metal fabrications section to be subject to the same technical requirements as in structural steel.