Gyp Rock

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Author Message HaroldFaber (Unregistered Guest) Unregistered guest Posted on Monday, April 15, 2019 - 05:55 pm:    What kind of Air & Vapor barrier products work best for traditional Gyp Rock products (Im talking about paper faced gypsum) like USGs Sheetrock or similar products? Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 475 Registered: 10-2003 Posted on Tuesday, April 16, 2019 - 12:20 am:    Air and Vapor barriers are not supposed to "work best for... gyp rock." The barrier works as part of an entire wall system and has to do with particular atmospheric conditions. Tell us more about what you are trying to do. Michael Chusid, RA FCSI CCS 1-818-219-4937 www.chusid.com www.buildingproduct.guru HaroldFaber (Unregistered Guest) Unregistered guest Posted on Tuesday, April 16, 2019 - 03:41 pm:    I understand that the entire building envelope works together to create an air and vapor barrier. What I am trying to understand is if I am using a USG Sheetrock product for example is there a specific AVB product I am going to use like a Tyvec or a Henry product or something like that. Specifically, looking at commercial midrise steel frame buildings is there a product that is most used? anon (Unregistered Guest) Unregistered guest Posted on Wednesday, April 17, 2019 - 04:53 pm:    Harold, On the surface, your question seems simple, and something that should be easily answered. But there are so many things that need to be considered and weighed before making a selection. There are many types of weather resistant barriers on the market. Each of them performs differently, and is used differently depending on the wall assembly, climate zone, and building code requirement(s). For example, it may be wise to go with a vapor permeable WRB in a mixed or cold climate, but vapor impermeable in a hot/humid climate. Another example, does the building code require that the WRB be tested as part of the wall assembly per NFPA 285? And if so, has the WRB product being considered been tested in accordance with this requirement? Most WRBs on the market meet air barrier requirements (but not all!). You will also need to consider the project's geographic region - I can specify a fluid applied WRB in some regions without worrying about Contractor's complaining and costing the project lots of additional money, in other regions not so much. If you can provide additional information about the project (location, wall assembly, etc.), this group could probably offer good product recommendations. HarveyMculloch (Unregistered Guest) Unregistered guest Posted on Thursday, April 18, 2019 - 03:58 pm:    Just ran across this post and had a very similar question I build primarily in the Southeast, 5-10 story commercial buildings, pretty new to the business. Im using Densglass gold are there any AVBs that you find go particularly well with the Densglass products. anon (Unregistered Guest) Unregistered guest Posted on Thursday, April 18, 2019 - 05:29 pm:    SE United States is typically hot and humid, which means you will more than likely need a vapor-impermeable WRB (0.1 perm or less). Self-adhering bituminous asphalt WRBs will work - Henry Blueskin is one, GCP and Soprema are two more manufacturers (there are many). If you want to go fluid-applied, GCP Perm-A-Barrier, Henry Air Bloc 06, and Tremco ExoAir 120 are good choices. All of the above are compatible / work well with DensGlass Gold sheathing. HaroldFaber (Unregistered Guest) Unregistered guest Posted on Thursday, April 18, 2019 - 11:37 pm:    Looks like Harvey kind of stole my thunder here. Anon I appreciate you taking the time to answer so thoroughly to this. I actually built in the Northeast, mostly steel frame structures. Based on your logic I am looking for the opposite of what Harvey is looking for then? A vapor permeable barrier? Thanks again man anon (Unregistered Guest) Unregistered guest Posted on Friday, April 19, 2019 - 12:07 pm:    Harold, Assuming that your wall construction includes energy code required continuous insulation outboard of the sheathing, and that thermal cladding support clips/rails are being used to mitigate thermal bridging (to meet energy code required clear field assembly u-value), it may not matter that your WRB is vapor impermeable, because in your climate zone (cold) with code prescribed assemblies, the WRB is thermally isolated. Which means that the temperature of the first condensing surface (from inside to outside) is the sheathing, and will never get cold enough for interior, moisture laden air to condense on that surface. Because of this, the permeability of the WRB is moot - there is no reason to allow it to breathe since no condensation exists, and therefore allowing drying to the exterior of the assembly is unnecessary. The WRB still needs to function as an air barrier, however, but nearly all WRBs meet this requirement. Vapor diffusion is not your primary concern with the assembly I have described. If no condensation potential within the stud cavity exists, all of the previously recommended products will work. Permeable WRBs will work in this assembly, in your climate zone(s) [mostly 5 and 6] as well, and each of the companies named in above offer vapor open WRBs as well, and any/all are be a good match with gypsum sheathing products. If any of this is unclear, let me know.