Joints in exterior sheathing at defle...

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Author Message Brian Payne, AIA Senior Member Username: brian_payne Post Number: 32 Registered: 01-2014 Posted on Tuesday, April 08, 2014 - 10:49 am:    I just got off the phone with a coworker who was told that the "industry standard" is to "gyp over" the deflection track with exterior sheathing. In this case the same subcontractor was responsible for designing the exterior studs with deflection tracks AND sheathing the building while ignoring the deflection tracks that they installed. They claimed that is how everyone does it. Do you typically detail exterior platform walls with deflection tracks? How do you handle the joint in the gypsum board? How do you handle possible conflicts where relieving angles are installed so close to the joint? MasterSpec is unfortunately not very clear in the standard specs. Looks like I'll be adding some custom language next time. Thanks! J. Peter Jordan Senior Member Username: jpjordan Post Number: 714 Registered: 05-2004 Posted on Tuesday, April 08, 2014 - 11:44 am:    Not sure what you mean by "gyp over". I would assume that the gypsum board was extended to near the top with a gap that was consistent with the deflection. Sheathing panels are not attached to deflection track. Joint needs to be treated to be consistent with air barrier. You might want to look at the manufacturer's printed instructions. These are sometimes at odds with what they do in the field which is not always a good thing. Alan Mays, AIA Senior Member Username: amays Post Number: 180 Registered: 02-2003 Posted on Tuesday, April 08, 2014 - 12:22 pm:    Brian, I would also look at the industry standard literature. The truth is many say industry standard and what they mean is, "that is what we always do, whether it is wrong or not." Look at resources like the Gypsum Association for one. Manufacturer's literature is also a good source. anon (Unregistered Guest) Unregistered guest Posted on Tuesday, April 08, 2014 - 12:44 pm:    Brian, your post is a little confusing. Are you asking about gypsum sheathing over the cold-formed-metal framed exterior wall? Or gypsum board over the same wall? These are two different products, governed by two separate ASTM standards for installation. When you say that MasterSpec isn't that helpful but I wonder, in writing that, have you looked up the reference standards that are cited in the MasterSpec sections? I often find what I need by doing that, when MasterSpec is not spelling it out for me... Brian Payne, AIA Senior Member Username: brian_payne Post Number: 33 Registered: 01-2014 Posted on Tuesday, April 08, 2014 - 05:06 pm:    Looks like my post sounded better in my head than when written out. The subcontractor, a well known reputable exterior metal stud wall installer, installed the deflection tracks (both at the head of wall and in some locations at the head of ribbon window)correctly. However, they also installed the gypsum board, but instead of aligning joints with the deflection track and taking care to make sure that the deflection load was not being transfered to the gypsum, they just installed the gypsum board continuous over the entire wall with no concern to the deflection tracks. One single board is fastened to the studs on both floors, spanning the deflection track, as if it wasn't there. What industry standard literature? I have looked, but cannot find information dealing directly with deflection track control joints. MasterSpec language briefly discusses not spanning expansion joints, but does not specifically mention deflection (control?) joints. Chris Grimm, CSI, CCS, SCIP, LEED AP BD+C, MAI Senior Member Username: chris_grimm_ccs_scip Post Number: 246 Registered: 02-2014 Posted on Tuesday, April 08, 2014 - 09:01 pm:    Brian, I do not see it in the usual resources like ASTM C 840 and GA-216. My first hunch was the same as Peter and Alan have said, your best bet is likely to be the manufacturer's instructions. Some of these tracks are still pretty proprietary, not lending themselves to standards I suppose. Here's where that is most likely invoked in your front end, even if not in the gyp section to remind them: SECTION 017300 - EXECUTION 3.[5].[B]. Comply with manufacturer's written instructions and recommendations for installing products in applications indicated.