Gage as a unit of measurement.

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Author Message Scott Mize Senior Member Username: scott_mize_ccs_csi Post Number: 80 Registered: 02-2009 Posted on Monday, October 07, 2013 - 02:43 pm:    How often do you see gauge (or gage) as a unit-of-measure for sheet thickness or wire/rod diameter? I've always found gauge problematic, because the gauges are (slightly) different for different materials. Ralph Liebing, RA, CSI, CDT Senior Member Username: rliebing Post Number: 1436 Registered: 02-2003 Posted on Monday, October 07, 2013 - 03:08 pm:    I am not sure it has taken universal hold, but a few years ago there was talk about not using gauge any more, but to use the actual thickness of the materials. These too, vary, as I recall, but apparently were more accurate than the gauges. Have some tables if you're interested. Steven Bruneel, AIA, CSI-CDT, LEED-AP, EDAC Senior Member Username: redseca2 Post Number: 412 Registered: 12-2006 Posted on Monday, October 07, 2013 - 03:22 pm:    I try not to use gauge in the specifications. But it is such a traditional expression in the construction community and on job sites I know it is impossible to completely eliminate (even reference documents issued by the State of California refer to "gauge"). My solution is to include a chart in the "Quality Assurance" article that pins gauge to a minimum decimal inch thickness in the Sections that include metal studs, hanger wires or similar items that may be defined by gauge. I include a column for bare metal thickness and galvanized thickness. Of course you learn from your mistakes: It has been at least 15 years now, but we once received a metal stud submittal where the actual metal thickness was just a little bit less for each gauge of the submitted stud product than had been factored by the structural engineer. Our drawings at the time referenced "gauge" without any dimensional thickness and the spec didn't elaborate. Jeffrey Wilson CSI CCS Senior Member Username: wilsonconsulting Post Number: 109 Registered: 03-2006 Posted on Monday, October 07, 2013 - 04:01 pm:    I use decimal inch values for metal thickness in the specs, or whatever else follows the applicable industry standard. For "trades" where gauge is still common (either in outdated manufacturer's literature or on the job site) I typically list standard gauge designations in parentheses as a convenience for users. So 20, 18, 16 & 14 gauge designations accompany thickness designations in my hollow metal section, and 25, 20, etc. gauges are listed w/ non-structural metal studs. David J. Wyatt, CDT Senior Member Username: david_j_wyatt_cdt Post Number: 30 Registered: 03-2011 Posted on Monday, October 07, 2013 - 05:08 pm:    The gauge standards do not permit variation, but the manufacturing processes, especially rolling sheet metal for construction materials, results in notable variations, thus manufacturer-generated "tolerances." We can insist on minimum thicknesses, but verification would impractical and very expensive. Within reason, it seems the best thing to do is to over-specify in order to compensate for the problem. Based on what I have read so far, using gauge to specify wire thickness is not an anachronism. ken hercenberg Senior Member Username: khercenberg Post Number: 619 Registered: 12-2006 Posted on Tuesday, October 08, 2013 - 07:13 am:    SMACNA has a good reference chart in its Appendices for sheet thickness equivalents to gage for various metals. Keep in mind that some metals specify by weight and some by thickness. Gage references for sheet seems to have gone by the wayside, especially with the advent of 'equivalent' products such as sheet used for studs. Wire, depending on the material, can usually be specified using AWG. Lisa Goodwin Robbins, RA, CCS, LEED ap Senior Member Username: lgoodrob Post Number: 222 Registered: 08-2004 Posted on Tuesday, October 08, 2013 - 09:40 am:    I agree with Mr. Wilson, and I keep a reference chart by my desk too. J. Peter Jordan Senior Member Username: jpjordan Post Number: 621 Registered: 05-2004 Posted on Tuesday, October 08, 2013 - 10:19 am:    This topic has been thrashed before in an earlier thread. The fact is that gage thickness was traditionally defined by each manufacturer with no standard for either steel or wire being formally adopted. Charts in references such as SMACNA, SDI, etc. are not formal standards per se, but general guidelines. Calling out gage thickness on the construction documents is accepting an ambiguous reference and opening the door to products that are not comparable. Lynn Javoroski FCSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 1698 Registered: 07-2002 Posted on Tuesday, October 08, 2013 - 01:04 pm:    Except when you have an Owner who insists on 18 gage studs...and when you specify 43 mil studs, they re-state that they require 18 gage. Ronald L. Geren, AIA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 1149 Registered: 03-2003 Posted on Tuesday, October 08, 2013 - 01:51 pm:    That's when you revise the specification to read, "Provide 18 gage studs having a minimum thickness of 43 mils." However, I think 18 gage is closer to 52 mils. Ron Geren, AIA, CSI, CCS, CCCA, SCIP www.specsandcodes.com Lynn Javoroski FCSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 1699 Registered: 07-2002 Posted on Tuesday, October 08, 2013 - 02:00 pm:    Not according to the information we received from Clark Dietrich. Here's part of the chart we now include: Comparative Steel Thicknesses: Steel Sheet Thickness for Studs and Runners Minimum Steel Base Metal (Uncoated) Thickness Gage inch mil 16 0.054 54 18 0.043 43 20 0.030 30 25 0.018 18 We also include similar information for high-strength steel studs which the contractor is allowed to use at their discretion, but we will call for minimum strength (which is part of the larger table). Ronald L. Geren, AIA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 1150 Registered: 03-2003 Posted on Tuesday, October 08, 2013 - 02:32 pm:    One thing to keep in mind is that if you use UL assemblies for fire-resistance-rated construction, the gages provided in the assemblies do have specific minimums for bare metal thickness. The bare metal thickness of an 18 gage stud is 43 mils. However, if the studs are galvanized with a G60 coating, then the total thickness will be closer to 52 mils. Therefore, if specifying 43 mils, then it should probably be specified that it is the bare metal thickness and not total coated thickness. Ron Geren, AIA, CSI, CCS, CCCA, SCIP www.specsandcodes.com Lynn Javoroski FCSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 1700 Registered: 07-2002 Posted on Tuesday, October 08, 2013 - 03:10 pm:    Yup, our table stipulates "Base Metal (uncoated) Thickness" Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 610 Registered: 10-2007 Posted on Tuesday, October 08, 2013 - 05:06 pm:    The manufacturer of dimpled metal studs uses a gage designation that may be misleading to many. What they are trying to say is that because the studs are dimpled they can provide comparable bending capacity while using thinner metal. When you are concerned about moment of inertia or other structural considerations then relying on the manufacturers gage designations can be misleading. Lynn Javoroski FCSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 1706 Registered: 07-2002 Posted on Tuesday, October 08, 2013 - 05:15 pm:    I don't think they make "dimpled" studs any more. They are now "high strength" studs. (the last measurement is inches; the information is from Clark Dietrich) ProStud 33MIL 0.0329 ProStud 30MIL 0.0296 ProStud 20XD 0.0220 Scott Mize Senior Member Username: scott_mize_ccs_csi Post Number: 81 Registered: 02-2009 Posted on Wednesday, October 09, 2013 - 02:36 pm:    Thanks for your responses, everyone. (And congratulations to Mr. Geren on being named a Fellow!)