Gypsum Sheathing

Archive of Older Topics Archive - Specifications Discussions
21

I never thought that my posting would generate so many answers. After reading them all, I cant arrive at a consensus. Opinions as to the location of gypsum sheathing are all over the map and the new MasterFormat doesnt resolve the issue.

Assuming that the project were specifying has steel studs (05400) and wood studs (06100), which is not that uncommon, then according to some, gypsum sheathing as a work result could be specified in 2 locations it doesnt make sense and we wont do that.

The only reason for MasterFormat to assign a Division 6 locator for this product is because people assume that its similar to wood sheathing; this may be true elsewhere, but not on the West Coast where wood sheathing is used to add shear resistance to wood-framed walls and is a structural material. Division 6 doesnt make sense either, at least for anything built West of Denver. As for insulation sheathing in Division 6, thats even more far fetched.

As for assigning a Division 9 locator, thats not better then trying to locate it in Division 6. Division 9 is labeled finishes; gypsum sheathing is not a finish material. I understand that gypsum is the major material in gypsum board and gypsum sheathing, but so is Portland cement in concrete and ceramic tile mortar.

If we take Bill Pegues first approach, which is to specify this Product as a part of a system, what is the poor specifier to do if both wood and steel studs are used on the same project? And how is the material supplier to know where the thing is specified? Remember folks that subs are not the only ones reading the specs. I prefer Shelby N. Gordonswyth and Bills second suggestion which is to assign a Division 7 locator for all sheathing, possibly excepting wood. It would then be easy to locate the product and I believe that is the only logical location for the sheathing.

Thank you all for this lively discussion. I believe thats what Colin had in mind when he created this forum.

22

As I mentioned previously, Firms I have worked for always specified the gypsum sheathing along with the other gypsum board products. I guess this will never be fully resovled.
For more fun and to add another wrinkle - where would you specify the building paper or “Tyvek-type” material that goes over the gypsum sheathing? In Div. 6, or with the gypsum sheathing?

23

In the same section as the sheathing, whether the sheathing is plywood or gypsum-based. The sheathing and weather barrier/building wrap/ whateveryouwanttocallit are part of a system and should be specified as a system.

24

Dave,
I was hoping someone would say that. I totally agree.

25

Which system?

If the gypsum sheathing is part of a composite that includes portland cement plaster, would it be part of the portland cement plaster Section in Division 9?

If the gypsum sheathing is part of the Exterior Insulation and Finish System, would it be part of a Division 7 Section?

If there are several composite finishes on the exterior, several of which include gypsum sheathing, would the gypsum sheathing be specified in several Sections? The same is true for building paper. And are joint sealers part of the finish composite or a separate matter?

Is this a case where there is no one true answer but several answers that are workable?

26

Wow, look how many of us have nothing to do on a Sunday afternoon!

I totally disagree that the air barrier material should be with the sheathing. Currently I only put the sheathing in the associated stud material section because it can be part of that system. I just don’t have a need to go to such lengths in my current practice. In addition, in my personal situation, the sheathing is not used with other materials.

I do have a place to put air barriers in an independent section, 07270 in MF1995.

And, where they may be part of the sheating stud system, they are also used elsewhere.

The air barrier material is a complete system in itself, independent of any particular substrate. If you put it just in the sheathing section, you run the risk that that is all that it is going to cover. So, you get no coverage over the other material substrate (concrete columns, slab edges, cmu backup…). You may show it, but you are really running a chance of raising a contradiction by the Contractor claiming that the air barrier is specified with the sheathing and metal studs, not with the cmu or the concrete.

Air barriers are meant to cover the facade - used only over some substrates, you have no air barrier system. Also, air barriers are more complex than just fastening something over the studs, there is all the taping, the special fasteners for the sheet products, the bridging materials over dissimilar substrates and the special preparations for penetrations (windows, doors, louvers, vents, etc.), flashing coordination.

There are also the different types of systems (sheet types, asphaltic types, acrylic types), there are the different transmission requirements (does it act as a water vapor barrier, or do you need something that blocks air and free water yet permits water vapor to breath through it), and do you support contractor options, permit or require different systems on different substrates (and then how do you bridge those).

William

27

William:

All I do on Sunday is watch the Olympics and troll through 4specs. What a life, eh?

Asphalt felts/building wraps are not, repeat not, air barriers. They are moisture barriers (which is different than vapor barriers/retarders).

I agree that air barriers go in their own section, 07270. But that is answering a question that was not asked.

28

Dave,

I don’t myself consider felts as a viable system for much of anything, unless I get caught in a timewarp back to the 1950s or so.

Tyvek, though I don’t really like to use it, it is generically an air barrier, falling into the category of water and air barrier, water vapor breathable. Here is a quote from the web site on this point…

begins…
Non-perforated Tyvek is continuous spunbonded nonwoven sheeting with a fibrous structure that naturally allows moisture vapor transmission. But, the micropores are small enough to resist liquid or bulk water and air infiltration.
<<<

It goes on to talk about how not all barriers perform all 3 funtions equally, which they say, theirs does.

I am not hyping for Tyvek, far from it. But they themselves consider their product an air barrier.

Even so, if all you are using it for is as a moisture barrier, do you still want to limit it only to covering the sheathing? What about over cmu that may occur on the same facade - and the concrete that is exposed. Hopefully the building wrap is put over the entire facade, not just the sheathing.

William

29

I think the answer to this question is again, it depends. If I specify it as an assembly with studs, I include it with the metal or wood stud section, and if I specify it as a stand alone work result, I include it in Division 06.

This is simular to the way I think about glass and and number of other products. It all depends on the project and the project delivery process for that project.

30

This whole Work Result thing is starting to confuse me now. I thought I had it figured out until I started reading this stuff about gypsum sheathing. Now Im not so sure. If one specifies gypsum sheathing in the Metal Stud spec section (because its screwed to one side of the studs), would I then expect to see gypsum drywall in the metal stud section too (its screwed to the other side of the studs after all) (the Assembly concept suggests that we might even include thermal insulation that gets installed in the stud cavity between the sheathing and gyp bd?) Where does it stop? The gyp bd gets painted; probably gets a resilient base applied; maybe gets an acoustical ceiling suspension system edge molding screwed to it; ,

We dont specify Roof Board Insulation in the Metal Roof Deck section. Why not? After all, the insulation gets screwed to the deck, just like sheathing gets screwed to studs.

If a project had both wood studs and metal studs, would we spec sheathing in both sections? To me this whole deal sounds like were locating the sheathing spec based, not upon that actual material or the Work Result but, upon Who is actually installing it! That flies in the face of everything we believe about specifying!

MasterFormat 2004 lists a specific location, 06 16 43 Gypsum Sheathing. I dont understand why I would want or need to spec it anyplace else (even though that looks suspiciously like a location based on the product and not a work result)?

31

Doug,

I am also confused. I thought that Uniformat was system/assembly based while MasterFormat was product based.

Am I wrong?

I also thought that MasterFormat is used as a product literature filing system, but have heard to the contrary.

32

Actually David, Dennis Hall has been preaching all along that MasterFormat is “Not” product-based but is broken down by “Work Results”. The most common argument being steel pipe; Handrails; plumbing piping; fire protection piping; Natural Gas; etc. Pipe has to be spec’d in the appropriate section(s) based upon its actual use (read Work Result) rather than only once in a Division 5 section.

I figured that made some sense in the beginning but anomalies keep cropping up, like gypsum sheathing, that make me question that decision.

I’m sure Dennis will weigh in here shortly with his thoughts as well.

33

MasterFormat is not a “pure” classification system, as Dennis (or another team member) pointed out in discussion some months ago. In a true classification system, each thing could only go in one place. MasterFormat, for compatibility with prior versions and for ease of use, will always have these anomolies–is it a material, or is it a work result, and whose work result is it? I think that it can accommodate them okay, and as this discussion thread shows, there’s more than one way to skin a cat.

34

I agree with John, its still the same as under MF 95. You have broad scope and narrow scope sections. If I had a project with wood and steel stud framing, I would most likely use Section 06 16 43 for gyp sheathing, where as if I have a small office remodel, I put metal studs and gyp in the same section. Its up to the judgement of the specifier how complex the project or system is and which type of section you need. The big difference now is that almost everything you would use on a “typical” job has been assigned a narrow scope number.

35

As an aside: I just want to chime in with my one point five cents. I once thought that every book in America had the same catalog number (as content belongs in a spec section) in every library. Then my wife went to library school, and I learned the location of some books vary from library to library, depending on the librarys collection, history, and experience with their patrons. Just as a book on Frank Lloyd Wright would be filed under the architecture heading in a small public library, or under the Frank Lloyd Wright heading in a large architecture school library, the location for gypsum sheathing will vary for us, depending on the overall job, our local conventions, and the experiences weve had with contractors.

Randy

36

Good point, Randy. Not to mention that some libraries use the Library of Congress System, whose numbers are conveniently printed on the back of the title page, and some use the Dewey Decimal System, which I understand is copyrighted and trademarked, but still used more “freely” (as described above). (But booksellers use still another system - ISBN.)

Since sheathing (of whatever kind) and building paper ('nother thread…) make most sense in Division 07 - not 06 - I may well exercise my specifier’s prerogative to put them there, in sections of their own (maybe lumping building paper together with air barriers, vapor retarders and kindred products in a section of their own.)

Is it too late to move sheathing from 06 16 43 to Division 07 in MF 2004? If so, can it be done on the errata slip, or the 2005 supplement? (Or, as with MF95, the second, corrected printing?)

37

I think we should put gypsum sheathing, building paper (“weather barrier”), air barriers and other miscellaneous stuff we can’t agree on a location for, in Division 17 in a Section such as “170005 - Miscellaneous Stuff”. We could also include foundation drains that are within the 5-foot line that the civil engineer refuses to specify as part of the storm drainage system and the mechanical engineer refuses to include with rainwater leaders.

38

Actually, I proposed some time ago a Division 19-5/8 to some of my colleagues. It would include all the stuff the A/E thinks is needed, but doesn’t put on the Drawings (or in the Specs).

I have heard of a Contractor who carries a line item for SICS (Stuff I Can’t See)-varies depending on the type of building, the owner, and the architect. His SICS factor is definitely higher with some architects because of their use of Division 19-5/8.

39

Division 19-5/8? Is that the metric version of MasterFormat?

40

John, Haven’t you read or seen the Harry Potter stories? They depart from platform 9-3/4, which, if you are a muggle, you can’t get to but if you are a wizard, you have no trouble reaching! Clearly, if you are a spec wizard, Division 19-5/8 is easy to spec.