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Thermo Ply or OBS/Tyvek

George2 | Posted in Construction Techniques on September 29, 2004 11:39am

During my precon meeting with my custom home builder, I was “informed” that they would be using Thermo-ply instaead of OSB sheathing wrapped in Tyvek.  I told them I would have to research the Thermo-ply before I agreed.  I left the meeting and went straight to a home they are building and looked at the Thermo-ply.  It looks like 1/8″ MDF with a paper coating to me.  I am building in Northern Virginia.   Is this a better (pronounced “right:) sheathing option for me?  The house will be clad in vinyl sidding.  I already had to make a special request for the Tyvek wrap (which I should not have had to do) and now this change.  Do I still need the Tyvek if I go with the Thermo-ply?  Does the Thermo-ply require any special application treatment like caulking between pannels?  Any help would be appreciated.

George

 

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  1. User avater
    JeffBuck | Sep 30, 2004 12:21am | #1

    I just ran into ThermoPly for the first time a coupla weeks ago.

    being a remodel .. I had to replace what I took out .. using the same materials ...

    so more thermoPly it was ...

    the print on the sheets said to just over lap the stuff ... and the original installers stapled the hell out of the stuff.

    to me ... it looked like ... and was just like working with ...

    tin foil covered cardboard.

    I'd not install ... on purpose ... any "sheathing" you can cut with a utility knife!

    I don't see how it can add any rack resistance at the corners either.

    are these customers looking for the absolute cheapest house ever built?

    Jeff

    Buck Construction, llc   Pittsburgh,PA

         Artistry in Carpentry                

    1. blue_eyed_devil | Sep 30, 2004 02:38am | #5

      Jeff, if the thermo ply is installed and fastened according to specs, it is indeed a wind brace. Tests have proven that. My own experience tells me that it's much stronger than foam and simpson t braces. Water won't penetrate it on vertical applications.

      It's actually a better underlayment than osb, but osb is marketed better.

      It might have a vapor barrier problem....not letting the inside moisture out. 

      blue If you want to read a fancy personal signature...  go read someone else's post.

      1. User avater
        JeffBuck | Sep 30, 2004 04:14am | #7

        I can say that installed under the 10 year old aluminum siding I pulled and reinstalled ... aside from the areas right on top of the way rotted framing ...

        which was next to the disintegrated wood window jamb ...

        that the thermoply was still in pretty good shape.

        Looked to handle the rain that got past the aluminum siding well.

        as it was ... out of the window ... the framing .. and the thermo ...

        the thermo ply held up the best.

        I'd think it OK for garages and such with proper bracing ...

        and it'd be stronger that the new garage packages they sell with dow board as the stuctural sheathing.

        still .. for houses and additions ...

        give me ply or osb at the least.

        I'll never build a whole housing division ... so the cost savings would never add up enough to think otherwise.

        JeffBuck Construction, llc   Pittsburgh,PA

             Artistry in Carpentry                

  2. flangehead | Sep 30, 2004 12:29am | #2

    I'm also in northern VA and thermo-ply (TP or toilet paper for short) is a standard sheathing used around here on tract homes. OSB is used on higher end homes. Tyvec seems to be optional on any price level home around here. I haven't seen ply used for sheething in years except on projects I do.

    1. robteed | Sep 30, 2004 02:22am | #3

      In a builder in Michigan, I had to install it on an attached garage

      in the Detroit area, Its JUNK! I will never build with it again!

      Doesnt come close to OSB.

  3. blue_eyed_devil | Sep 30, 2004 02:33am | #4

    George, we used to use either thermo ply or "celotex" ( a mineral fiber board) around here back in the 70's. Those houses are still standing quite sturdily. Most were brick veneers, but some were sided.

    We still are using thermoply on the attached garage walls today, especially after the osb went throug the roof last year. Evven before that, some builders simply preferred the thermo  ply. Old habits die hard....especially when they work and they haven't had any problems.

    The pros are simply economy. Thermo ply is an adequate sheating that was marketed as a suitable replacement to celotex in the 70'w. It seems we've come full circle. In the energy conscious 80's, the builders switched to foam. By doing so, they sacrificed rigidity for energy savings. They used the rationale that the rigidity was not needed and the walls could be properly windbraced using alternative methods (the simpson t brace surfaced).

    The cons are not that bad. Thermo ply will not help straighten crowned studs the way osb does.

    Thermo ply also complies with windbracing requirments if all the nailing patterns are followed. Fortunatly, that is easy because they put little red marks where every fastener is required. It is sized to lap (it used to be 49"...i haven't measued any in years) but it is critical to have it hit both top and bottom plates if it's used as a windbrace.  All horizontal joints would have to be blocked and nailed too.

    We prefer to install t braces rather than following the nailing patter. It simply becomes an insullation barrier then.

    If you properly thermoply a house, you probably wouldn't need any tyvek. There ain't no air or water penetrating through the foil if it's nailed at 2" oc on the seam!

    If you're wealthy, demand real wood sheathing, foam and tyvek. If your blue collar, then just be thankful that you aren't making igloos.

    I'd spend my extra money on Corian countertops with undermounted sinks!

    blue

    If you want to read a fancy personal signature...  go read someone else's post.
    1. User avater
      Timuhler | Sep 30, 2004 02:50am | #6

      We used Thermo-ply back in the early 90's but switched to all double wall construction in the mid 90s.  I had the lucky privilege of hand nailing the 2" or 3" oc.  Recently I've wondered if you could use it on the inside of the wall for a greater shear wall value.  It's just a thought.  I attended a recent Home Builders Association meeting where the county plan checker was going over prescriptive "braced wall panel" requirements.  I didn't think to ask him then, but he was talking about small "braced wall segments" and mentioned that you could sheathe both sides of a smaller wall segment (2'8" or less) to get the required shear value as a substitue for a 4' wall.  I'm wondering if you had 2'8" from the corner to the window, if you could use thermo-ply on the inside so that no firring would be required.  Just a thought.

      1. blue_eyed_devil | Sep 30, 2004 05:48am | #8

        Tim, how would you insulate if you sheathed inside?

        blueIf you want to read a fancy personal signature...  go read someone else's post.

        1. User avater
          Timuhler | Sep 30, 2004 03:56pm | #10

          Put it on after the wall was insulated.

  4. xMikeSmith | Sep 30, 2004 06:19am | #9

    George... we used a lot of thermo-ply.. one advantage is that you can get it in 10' sheets , so it can lap from the foundation to the top plate or beyond..

     there were two types.. one type (red label i think) was structural for racking resistance..

     it is a fine sheathing material if you are using horizontal siding ( like your vinyl siding)..

    i would still like to have an underlayment.. tyvek if you want.. i prefer 15# felt

    here is our house... this is a Thermoply house, built in '85

    Mike Smith   Rhode Island : Design / Build / Repair / Restore

    1. George2 | Sep 30, 2004 05:20pm | #11

      The problem I'm having with all this is that about six months ago my contractor sent me a letter stating that because of the elapsed time from when I signed the contract, that the cost of my construction was increased $4K.  I accepted this.  He also stated that because of other problems, our house would be stick built rather than a pannel home.  I'm not haooy about that because I was attracted to the idea of getting it buttoned up from the elements as quickly as possible.  Now we a month away from breaking ground and they are bringing the TP into the picture.  If I go with the TP should I request the 15# felt over it instead of the Tyvec?  What is the cost difference between the OSB and TP?  Using TP will not impact my cost.  It will likely only increase their profit.  

      George

      1. rez | Sep 30, 2004 05:37pm | #12

        How much is going to be saved on the whole house by going with TP as opposed to 7/16 osb?

        Must be a kickin' big house to be worth the savings.

         

        Edited 9/30/2004 10:38 am ET by rez

        1. George2 | Sep 30, 2004 06:35pm | #13

          Rez,

          The house is not that big, 3600 sq ft.  I am not the one who will relize the savings.  My builder is trying to substitute materials for the same cost to me.

          George

          1. rez | Sep 30, 2004 06:49pm | #14

            George-

            I don't know your situation but if it's the house you are building to live in yourself, and somehow you are stuck with the contractor using the TP for his pay, I would want to know how much more out of pocket would it cost me to substitute osb in place of the TP. Thinking it couldn't be that much more.

            I mean osb price subtracting what would be the TP price on how many sheets? The TP just doesn't have that assurance ring to it.

            Meaning it would probably work as the other posters have commented, but it's the structure on the house you will live in.

            Some builder's put nothing but 5/8 ply on the outside walls and 5l8 drywall inside for stability, quietness and that solid feeling.

            For what it's worth as a non-professional homeowner I say find a way to a happy compromise and put osb on those walls.

             

      2. fredsmart48 | Sep 30, 2004 07:29pm | #15

        Do you have a signed contract with this General contractor (GC) if you do what it says as far as substituting materials. Does it have materials price escalator clause in the contract.

        It sounds to me some thing like bate and switch in reverse. That is sell you some thing with better quality building materials and switch to some thing cheaper and still charges you the same or more for a cheaper home.

        Over all it sounds like you need to talk to YOUR attorney. The same attorney that you took that contract before you signed it; to advise you as how the contract protected you from just such problems you seem to be having now.

    2. JohnT8 | Sep 30, 2004 08:33pm | #16

      Hey Mike, did you finish that addition you were posting pics of?  Can't remember seeing any recent pics.  Did you use TP on it?

      jt8

      1. xMikeSmith | Sep 30, 2004 11:09pm | #17

        john ... i'll get some more up soon..

        no.... i haven't used TP in quite a while... mostly because i build for my customers... when i do that i use 1/2 ply for the walls, 3/4 Advantech for the floors, and from now on i'll be using 5/8  T&G Advantech for my roofs..

         if i was building for  myself.. i'd use the TP as long as it still meets code.. which i'm not SURE of with the new wind load requirements and shear wall specs..

         for my siding i'd be using Certainteed Fiber Cement... so i don't need a nail base... all my siding would be nailed into the studs at 16" oc

        here's some more of our ThermoPly buildings

        the big one is a professional condominium office we designed and built in '85

        the 3-car garage is in back of my office, we built this in '95..

        they all use the same siding.. ( pre-fibercement )... Atlantic White Cedar STK clapboardsMike Smith   Rhode Island : Design / Build / Repair / Restore

        1. xMikeSmith | Sep 30, 2004 11:23pm | #18

          they wouldn't post... so we'll try again....

          nope.. my "attach files" button ain't workingMike Smith   Rhode Island : Design / Build / Repair / Restore

        2. JohnT8 | Sep 30, 2004 11:24pm | #19

          You might wanna UL those pics again, I'm having a hard time visualizing.  Oh sure, figure the pics our for yourself before I can say something...

          Seems like a lot of Advantech fans on this forum.  I've never used it.  Maybe I'll give it a try on the next floor I run into. 

          I tend to be a ply fan (despise MDF and am trying to learn to tolerate OSB).  On exterior sheathing, if you had a pile of 1/2 ply, 3/4 OSB, or TP, you would really choose the TP?

          jt8

          Edited 9/30/2004 4:25 pm ET by JohnT8

          1. xMikeSmith | Sep 30, 2004 11:39pm | #20

            john..if it is my property... or even my spec house..and the code accepts the TP

            i'd use TP for the walls, 3/4 Advantech for the floors and 5/8 Advantech T&G for the roof..

            and Fiber Cement for the siding.. kind of like blue says... the TP is a great product FOR IT'S INTENDED USE.. so why not save the money and put the savings to use some place else ?Mike Smith   Rhode Island : Design / Build / Repair / Restore

          2. xMikeSmith | Oct 01, 2004 04:04am | #21

            try again.. different coputerMike Smith   Rhode Island : Design / Build / Repair / Restore

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