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Community and Q&A

Airtight Drywall… Anyone?

John Brooks | Posted in Energy Efficiency and Durability on

There are a handful of people here at GBA talking about Airtight Drywall.

Have you tried it?
Would you do it again?

I am trying to figure out why there is not much discussion about it?

I will post a link to Martin Holladay’s FHB article and a Link to the BSC instructions.

Does anyone have other links to Airtight Drywall Details?

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Replies

  1. Lucas Durand - 7A | | #2

    John, it's a bit of a long read but I learned some interesting things about ADA here:
    http://www.greenbuildingadvisor.com/community/forum/energy-efficiency-and-durability/19107/airtightness-sans-sprayfoam
    This PDF has a cut-away that shows "goo-as-you-go":
    http://www.greatlakeshomeperformance.com/elibrary/Airtight%20Drywall%20Approach.pdf

  2. Lucas Durand - 7A | | #3

    The CMHC has a series of details for different envelopes using ADA. Unfortunately, it seems they want you to buy their "Best practice guide" so the details don't have very good resolution:
    http://www.cmhc-schl.gc.ca/en/search/search_001.cfm?sec=bs&os=ada&text=airtight+drywall

  3. User avater GBA Editor
    Martin Holladay | | #4

    John,
    I presume you've seen this document:
    Airtight Drywall Approach.

  4. User avater GBA Editor
    Martin Holladay | | #5

    John,
    This is GBA's detail page on the Airtight Drywall Approach:
    Air sealing strategy at wall framing elevation.

  5. John Brooks | | #6

    Thanks Martin & Lucas,
    The Energy Fact Sheet #24
    and the CMHC details are "new to me"

    The Energy Fact Sheet 24 does have some subtle differences to the other details that I have seen
    I will be looking at CMHC details too

  6. John Brooks | | #7

    From Martin's FHB Article:

    A wide variety of caulks can be used for airtight drywall, but most experts recommend polyurethane for sealing drywall to framing. Gaskets, however, outperform caulk in this application.

    Martin,
    How do you know that Gaskets outperform Caulk?
    It makes sense ... sounds like gaskets would be better...
    But....
    Do you know anyone who is using drywall gaskets?

    Do gasket "jobs" get better blower door results?

    I like the idea of mostly gaskets and just a little bit of gooey stuff.
    I would like to get some feedback from someone who actually uses or has used gaskets.

  7. User avater GBA Editor
    Martin Holladay | | #8

    John,
    Michael Chandler uses gaskets for the ADA.

    Hans Porschitz at Bensonwood Homes is one of the most knowledgeable people I know about the advantages of gaskets -- generally preferred by European builders -- over caulk or spray foam. Bensonwood Homes have tested all three for sealing seams, and gaskets win.

    I wrote an article about gaskets for the March 2004 issue of Energy Design Update. In the following paragraphs, the discussion concerns the superiority of gaskets compared to spray foam, not caulk. But I think the discussion is still relevant:

    "Porschitz convinced a customer to allow Bensonwood workers to use EPDM gaskets from a Swedish company called Trelleborg to seal the seams between the SIP roof panels on their new home. A Trelleborg gasket consists of two parallel 3/8-inch-diameter hose-type gaskets vulcanized to a strip of polyethylene plastic (see Figure 5). These gaskets are available in a variety of widths, ranging from 31⁄2 to 8 inches. “I’m originally from Germany,” says Porschitz. “In Germany, the joints in panelized homes are always filled with rubber gaskets, because they’ve found that foam just doesn’t work in a wooden house.”

    "Bensonwood hired Bruce Torrey, an air-sealing contractor from East Sandwich, Massachusetts, to compare the airtightness of the gasketed home with a nearly identical home with foam-sealed SIPs. “We tested the two houses with infrared and a blower door,” says Torrey. “We saw what a dramatic difference there was. The seams with gaskets worked and the seams with foam didn’t. People assume that SIPs seams are airtight, but they’re not. You could really see it with the infrared—at the house with foamed seams, you could see infiltration coming in at every joint. When we depressurized the house, you could feel it with your hand—where the SIP panels sit on top of the rafter on a cathedral ceiling, and where the panels butt each other. It’s easy to blame the foam, but the problem is that the foam is put on by humans. Depending on how careful the guy is with the foam gun, some beads are better than others. The gasket is more foolproof. It is consistent and has good memory.” "

  8. User avater
    Armando Cobo | | #9

    John,
    Every set of drawings should have ADA details and every house should be built this way... starts with us at the design community.

  9. John Brooks | | #10

    Armando,
    Could you post a copy of your ADA details?
    thanks,
    John

  10. John Brooks | | #11

    Martin,
    your post confirms my thinking about gaskets...
    Except that your examples are for SIPs

    Who is using EPDM Gaskets(not Sill-Seal) with drywall?

  11. John Brooks | | #12

    Lucas,
    You have inspired me to add a "RED line" AND "a BLUE line"
    to my IN-Progress (Airtight at Drywall & Sheathing) Illustration
    Red is Outside and Blue is Inside

    here is a higher res PDF
    http://dl.dropbox.com/u/16030874/airtight%20at%20drywall%20and%20sheathing.pdf

  12. John Brooks | | #13

    This is how I imagine the "Inside" and "Outside" lines would look if the "Exterior Wall Drywall" is not detailed for "airtightness"

  13. William Goodwin | | #14

    Does anyone know of a source for fewer than 1,000 drywall clips?

  14. User avater GBA Editor
    Martin Holladay | | #15
  15. Lucas Durand - 7A | | #16

    John, your air barrier detail looks very simple and resilient.
    I like that it has the potential to maintain its integrity in different "failure modes".
    I really like the coloured lines. I would be nice if these could be a part of working drawings. If you don't know what you're looking for, subtle details can be easy to overlook.

  16. Lucas Durand - 7A | | #17

    I like the idea of mostly gaskets and just a little bit of gooey stuff.

    I also like more gaskets and less "goo".
    Robert put me on to these gaskets from Conservation Technology:
    http://www.conservationtechnology.com/building_gaskets.html
    I think I'll be placing an order in the next few weeks.

    If you can wait, I should be able to give you some feedback by next fall ;-)
    Hopefully I'll be in psoition to do a blower-door test by then.

  17. Dan Kolbert | | #18

    Another advantage of gaskets is that they can be installed before the sheetrockers arrive. Unless you're hanging yourself, it's going to be an uphill battle. They generally work at a piece rate and are temperamentally opposed to anything that would slow them down. And who can blame them.

    We've used Conservation Technology's drywall gaskets - I like them.

    I saw your post at JLC, too, John - I'll post this there. Very interested to see how the DW pros there react. Poorly, I'm guessing.

  18. John Klingel | | #19

    I see the purpose of the gasket/goo between the bottom plate and sheet rock, but I don't see its purpose on the top plate(s). If you have a double stud wall system, it seems that any air that you stop from getting between the sheet rock and the top plate(s) is just going to slide around the top plate on the other side. Besides, if you use air tight electrical boxes, dense pack w/ cellulose, and gasket the bottom plate, you should not really have much air moving in the wall anyway, right? Did I miss something? thanks. j

  19. Lucas Durand - 7A | | #20

    John (Klingel),
    I think John's detail is specific to his hot/mixed humid climate - where two air barriers may be better than one for durability reasons.
    The gaskets at the top plate allow the air barrier to transition from the ceiling drywall across the top plate to the "airtight" sheathing at the exterior.
    I'm not sure the detail could be used with double/truss wall systems - possibly a crosshatch.
    I'm not sure that very high-R assemblies are required in John's climate.

  20. John Brooks | | #21

    John Klingel,
    I want to make sure I understand your question...
    Are you asking about the need for the top plate gasket for Airtight Drywall Approach?

    Or the need for the top plate gasket with "double stud wall system"?

  21. Daniel Ernst | | #22

    Lucas,

    I'm not sure about Texas not needing a High R-Value assembly. At the 2009 PH Conference, Katrin Klingenberg gave this presentation:

    http://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxwaGNvbmZlcmVuY2VvY3QxNzIwMDl8Z3g6MThmZmYwNWFjZGIwZjQyZg

    See p. 10 - 12

    Chicago Wall - 356 mm Thick
    Ashville Wall - 241 mm Thick
    Houston Wall - 305 mm Thick

    I know Dallas is not Houston, but the thinnest wall is still > 9" thick, using blown fiberglass!

  22. Daniel Ernst | | #23
  23. Daniel Ernst | | #24

    Of course, we know which fork in the road they took! ;-)

  24. Lucas Durand - 7A | | #25

    I'm not sure about Texas not needing a High R-Value assembly.

    I guess I need to live in a hot mixed/humid climate for a while.
    I often get caught thinking "cold-centric"ly.
    I tend to think of warm (even hot) climates as being not as extreme as cold and very cold clmates.
    I forget how much people lke to air-condition.

  25. John Brooks | | #26

    Daniel,
    I had looked at that presentation.
    I think there are a lot of good ideas there.

    I would not call it affordable.

  26. John Brooks | | #27

    Lucas,
    We like to be somewhat comfortable just like most people.
    We currently spend more (&use more energy)to be comfortable than folks in New England.
    Air conditioning is more than just a luxury for us.
    It would be miserable here without it.

  27. John Brooks | | #28

    Daniel,
    the detail that I posted is intended as a baby step to improve current HforH methods in Dallas.
    I agree that much Higher R-values(wall & Ceiling) are needed for my climate.

  28. John Brooks | | #29

    I suppose if every cavity AND GAP in the exterior wall is "FILLED" with dense insulation or "goo"
    Then... air control at Drywall and/or at Sheathing is not-so-important

    but if there is an accidental gap or void........

  29. John Brooks | | #30

    I am trying to visualize the pressure boundaries with different air control strategies.

  30. Lucas Durand - 7A | | #31

    John, your diagrams in #30 illustrate what I was thinking when I said:

    I like that it has the potential to maintain its integrity in different "failure modes".

    "Resiliency" is good.
    Like using hygroscopic materials for "hygric buffering". Robert seems to be one of the few that emphasizes the importantance of "hygric buffering" with building materials.

  31. Lucas Durand - 7A | | #32

    Unvented roofs, poorly defined air barrier details, processed building materials and lack of "moisture management" are all examples of "holes" in the cheese.
    It makes sense to avoid lining them up to the extent possible.

  32. User avater
    Armando Cobo | | #33

    John,
    One can go nuts getting too technical and with expensive solutions. Every house we design has details to run beads of caulking on all plates, openings and bottoms of sill plates + sill sealer and good Thermal Bypass detailing. By always using blown-in and/or foam insulations and taped rigid insulation outside the sheathings, we always get <0.5% NACH and <1 ach50 regardless of the size house. common cense and simplicity will go a long way. i’m always thinking who* uses details, therefore need to be simple point.
    *(As in Spanish speaking crews in our areas or people with less than or no education in building science or architectural detailing)

  33. Robert Dickinson | | #34

    This is a very helpful discussion, as I appreciate the benefits of an ADA air-sealing approach, but lack the knowledge of the specific details to get it right.

    Some questions:

    1) What do people like for sealing electrical boxes? There are the Lessco enclosures, and I've also heard of some electrical boxes with flanges and foam gaskets, but I don't know who sells these. There are also the simple foam gaskets themselves that go under the outlet plate covers, but I don't know if they would work well enough to be sufficient.

    2) Some of the materials I have been reading were comparing the Airtight Drywall Approach to something called Simple Caulk and Seal (SCS). I've not really seen clear documentation for what SCS is and how one does it.

    Thanks!

  34. John Brooks | | #36

    Armando,
    I agree to Simple & Clear

  35. Matthew Amann | | #37

    Response to John Brooks answer diagram #29- So, if a PVA primer is used, how much vapor is really going to make it through a decently insulated wall and still hit dew point? If this scenario is likely, than seems like a good case for hygroscopic building materials like cellulose insulation and clay plasters........

  36. John Brooks | | #38

    Matthew,
    The Illustration(at post 29) is my rendering of an illustration from John Straube's (Building Science for Building Enclosures)
    It is showing that condensation is "possible" even if there are no air leaks to the outside.

    If the Cavities are well insulated with no gaps then I do not think it is likely.

  37. Robert Dickinson | | #39

    A question about "Goo" choices.

    A wide variety of caulks can be used for airtight drywall, but most experts recommend polyurethane for sealing drywall to framing.

    I like the gasket approach, and would probably want to use that wherever possible. But assuming that caulk/sealants are needed in some locations/circumstances, I'm interested in identifying the right one to use.

    I just read the Fine Homebuilding article on caulks and sealants -- see: http://www.finehomebuilding.com/how-to/articles/making-sense-of-caulks-sealants.aspx -- and it talked about how toxic and difficult polyurethane caulks are.

    The FH article seems to suggest that newer modified-silicon polymers (like DAP Side Winder and OSI Advantage) have most of the benefits of polyurethane (like flexibility, durability, adhesion, etc.) without the toxicity and with much less VOC content.

    Any thoughts on using these modified-silicon polymer caulks (Side Winder, Advantage) instead of polyurethanes?

    And how would these caulks perform relative to Tremco Accoustical sealant, aka the Black Death? The quote above suggests that polyurethanes are the best thing to use for sealing drywall, but reading this forum and others always seem to suggest that Tremco, while messy and a pain to use, is really the best choice.

    Ok, sealant gurus, please enlighten me on your best ADA caulk/sealant recommendations.

  38. John Brooks | | #40

    The photo at post 40 was taken at a Habitat for Humanity project in Dallas
    The current practice is to prefabricate the walls offsite.

  39. John Brooks | | #41

    Robert Dickinson,
    I will bump your question about "GOO"

    I also wanted to post an illustration of a mostly gasket strategy.

    I am thinking that by placing the gasket at the "lower top plate"....
    There will be less chance of damage when the ceiling drywall is installed
    (I also noticed that the Canadian ADA "gooline" is shown on the lower plate)

    Also for an affordable home with 8 ft ceilings the exterior sheathing can "gasket" to the same plate.

    This concept should also work with a Cross-Hatch Exterior wall

  40. 5C8rvfuWev | | #42

    What's the downside to 'mostly gasket'?

  41. John Brooks | | #43

    Joe,
    I had some feedback from Riversong about gasket downsides
    * they can get damaged
    *they can make the drywall "out-of-plane"
    *they have joints that need to be sealed

    I am thinking that damage and "out-of-plane" problems would not be such an issue in the locations I indicated on my detail.

    perhaps some "shimming" for out-of-plane problems and add gooey stuff at gasket joints and corners?

  42. John Brooks | | #44

    Joe, another downside might be cost

    I did some rough take-offs for a 1400 sf house
    at 20cents a linear foot
    material for "gasket drywall" AND "gasket sheathing" = approx $500
    that does not include labor

    The UPSIDE .... sprayfoam could be avoided
    The additional premium paid for sprayfoam is far more than $500

  43. John Brooks | | #45

    I noticed a recent Q&A question about Drywall Gaskets and thought I would bump this old thread.
    I continue to believe that there is a future in Gaskets and Airtight Drywall.

    There must be someone "out there" who is employing Airtight Drywall???
    I would love to hear from people who have had sucess (or Not) with Gaskets.

  44. User avater
    Daniel Morrison | | #46

    We just sent an issue of FHB to the printer with ADA as the cover story. Myron Ferguson, our serial drywall author installed it in the garage shop of our [Project House](http://www.finehomebuilding.com/projecthouse).

    He used Big Stretch, latex construction adhesive, and canned foam. The outside of the shop is in the process of getting new house wrap and rigid foam, so the interior drywall is part of the system, rather than trying to do it all.

    First step was to seal gaps between framing with caulk (Big Stretch) -- between top plates, king stud/trimmer, bottom plate/floor, etc.

    When hanging the drywall, Myron applies adhesive to the face of the framing. He likes latex construction adhesive because there is a longer open time. He can cover a whole wall and then hang all of the drywall. He breaks the butt seams in framing cavities rather than on studs, joists, or rafters. He does this mostly because he can do a better job taping it, but it helps in the event of a leak because it cuts the consequences in half -- from two cavities to one.

    Around windows, he used both adhesive and caulk -- a bead of caulk around the rough framing instead of adhesive because the caulk would remain flexible. We also sealed the edge of the window with canned foam and used a gasket on the sill.

    We also showed a 'good, better, best' approach to electrical boxes -- caulk and canned foam; caulk, canned foam, and an eps box with adhesive; and an airtight box.

    After the drywall is up, he hits the perimeter gaps with canned foam.

    The video will show up here on GBA in about a month (sorry, it is for GBA PROs only).

    Dan K: Myron saw an opportunity (how his trade affected home performance) and decided to get BPI certified. Airtight drywall approach is an excellent opportunity for drywall contractors to charge more money. Pay $500* for a class once, charge an extra $500 on every job for the rest of your life. Seems like pretty simple math.

    *or however much BPI certification costs...

  45. Dan Kolbert | | #47

    It's a great idea, Dan. I'll be very curious to hear if he thinks it'll pay off. It would be nice to hear there's a huge market for his new skills but I know my colleagues too well to be optimistic.

  46. Milan Jurich | | #48

    Have you considered using a product like OC's Energy Complete ... creates many "compressible" gaskets along the surfaces that have been treated. See Martin's article below:

    http://www.greenbuildingadvisor.com/blogs/dept/musings/air-sealing-sprayable-caulk

  47. User avater
    Daniel Morrison | | #49

    Dan,
    When I was remodeling in Portland, we used a drywall guy who caught my attention in a good way. He and his helper played a memory game while they were hanging drywall: they began with the current president and worked backwards reciting who the president was, and then what he was famous for before he became president.

    Not to disparage the drywall profession, but he seemed like a step ahead of many drywallers. I think his name was Ed Duplessis. Maybe he is interested in upping his game.

    Dan

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