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What would be the proper way?

Varrat1973 | Posted in Green Building Techniques on

120 year old remodel. The home is balloon framed with no breaks between floor joists and outside walls. I have been battling air movement in the house and now that it is time for siding I am confused because the house has no wall sheathing. It is just lap wood siding nailed to the studs.

So I am wondering what is my best choice for an air barrier that also acts as a wrb for northern Ohio.On cold windy days there are areas in the house you can feel serious drafts coming through the 120 year old gapped heart pine floor. I am hoping by selecting the best air barrier moisture barrier before applying vinyl will help cut this down a lot. I have sealed up the basement and vented the roof which has made a large difference but there are certain walls that still have serious air movement. The wood siding on the exterior is in poor shape in places, but there have been no signs of interior moisture damage. Would I be better to use 30lbs felt or a tyvek product. The home has been fully gutted reinsulated using kraft faced batts and new drywall installed everywhere. Thanks Martin for directing me here. I appreciate any feedback from any of the professionals on here.

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  1. iLikeDirt | | #1

    If you're planning to tear off the siding and expose the sheathing-less framing, you have a good opportunity to add a lot of insulation from the exterior. You said you've already put fiberglass batts between the studs. As you've discovered, fiberglass is air-permeable. I would recommend adding sheathing of some sort. It could be plywood or foam. Plywood will add extra racking resistance, if that's a concern. Whatever you use, you should tape the seams to stop air entry, and use a water-resistive barrier over that. Tyvek or tar paper should both work fine. At that point, you would have a perfect opportunity to add even more insulation over your sheathing (or, if you choose foam sheathing, to make it even thicker). You could use rigid foam or rigid mineral wool for this. Make sure you have enough for your climate:

    Northern Ohio is zone 5, so you'd need at least R-5 if the studs are 2x4s, and at least R-7.5 if the studs are 2x6s. More is always better!

  2. Varrat1973 | | #2

    Nathaniel thanks for the response. The house is a large 2.5 story and that really is more work than I am wanting to get into at the moment. What if I left the clapboard siding and considered that my sheathing and worked from there. Would I need to add tyvek and furring strips for the new vinyl? I realize the old clapboards need to breathe. I am a little confused on how to go about this without removing the old clapboards, I also would think they do provide structural integrity to the walls?

  3. Richard Beyer | | #3

    Most siding crews in S.E. Connecticut install fan-fold rigid foam insulation and then siding over the old siding. Rarely did they ever tape the seams. I'm not saying what they are doing is correct, but this has to account for the majority of installations I have seen over the last 30 years. These homes may not be energy efficient, but they are not falling down due to the siding installation.

    Your correct answer may be found here at the Vinyl Siding Institute....

  4. GBA Editor
    Martin Holladay | | #4

    I don't suggest that you cut corners or try to find an inexpensive way out of your dilemma.

    Unfortunately, you have already made a major mistake. You did a gut rehab job on the interior of your house, and you installed insulation in your walls without thinking about the need for an air barrier. Now you are experiencing the results of that mistake.

    It is challenging to know what to do with a house that has no wall sheathing. There are two ways to address this type of problem: one from the interior, and the other from the exterior. It's already too late to address the problem from the interior, because you squandered that opportunity.

    From the exterior, the solution is to remove the existing siding and install an airtight layer of sheathing (plywood, OSB, or rigid foam with taped seams). If I were doing the work, I would install plywood with taped seams, followed by rigid foam, vertical rainscreen furring strips, and new siding.

    For more information on these issues, see the following articles:

    Questions and Answers About Air Barriers

    How to Install Rigid Foam Sheathing

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