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+100-year-old house remodel: Flanged window installation & wall retrofit

JayneMarie | Posted in General Questions on

Hello All,
I am remodeling a +100 year old house (located 2 hours south of Chicago, IL) and will be installing Andersen 200 Series Double Hung windows (6’x3’) that have vinyl nailing flanges.

Existing exterior wall construction from inside to out:
Plaster and shiplap (keyed to hold plaster) (both removed to add mineral wool insulation to stud cavity), 2×4 studs (original and new), horizontal lapped board siding, asphalt (or asbestos?) shingles, vinyl horizontal siding (removing to replace).

The original plan was to remove all exterior siding down to studs and retrofit with plywood, foam & new vinyl.
I no longer want to do this.

My plan for the exterior is to: remove the vinyl siding, install windows/doors, replace the vinyl siding.

My plans for the interior are:
A) Install ¼” – 3/8” plywood on interior side of stud wall (tape all joints and edges to air seal), add 1 to 1 ½” polysio (foil facing inward), strap with horizontal 1×4’s, add ½” sheetrock.
B) Install drywall over studs. Use Airfoil electrical boxes. I have also considered using either UltraTouch acoustic strips or Plymouth Foam Sill Seal gasket between the exterior studs and drywall to reduce thermal bridging. Previous experience found the UltraTouch product difficult to work with.

My questions are:
1 Would Dudley Boxes (GBA 01/25/13) work for this application? (Dudley Box flange (approximately 3”) nailed to the 2×4 studs and the flanged windows nailed to the Dudley Box) Would that support the weight of these windows? Or would you suggest another method?
2 How should I flash /seal the vinyl window flanges to the existing asphalt (or asbestos) siding? Siga Wigluv or Grace Vycor Pro or other?
3 Would interior plan A be worth the effort and cost over plan B? Would the ¼ – 3/8” plywood add any structural benefit?

Your thoughts and comments would be greatly appreciated.
Jane Campbell

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  1. GBA Editor
    Martin Holladay | | #1

    A few comments:

    1. If your house really had a layer of shiplap boards on the interior, and if you removed them, it's possible that these shiplap boards served to help brace your walls (especially in light of the fact that your house apparently lacks any exterior sheathing). You might want to consult an engineer to verify that your plan to install 1/4 inch plywood on the interior will provide enough wall bracing.

    2. Unless I missed something, you don't mention any plan to install insulation between your studs. Are you going to insulate this wall? If so, what type of insulation will you install?

    3. I'm confused by A) and B). At first I thought that these were two steps in your remodeling plan. But now I am beginning to think that these are two different alternatives. Which is it?

    4. The Dudley box system was developed for retrofits that include a continuous layer of exterior rigid foam. I don't think that you are planning to use exterior foam, so I'm not sure that the Dudley box approach makes sense for you. As you guessed, you can't really seal window flanges easily to asphalt shingle siding (although it's possible to seal flanges to asbestos siding).

    The type of siding you have matters. Asphalt shingle siding is much different from asbestos-cement siding.

    5. One issue you haven't addressed is the need for a water-resistive barrier (WRB). What did you plan to use as a WRB?

    For more information on WRBs, see All About Water-Resistive Barriers.

  2. JayneMarie | | #2

    Thank you for your reply. 1) I will seek additional advice regarding use of 1/4 - 3/8 plywood. 2) I will use mineral wool (R15) to insulate the exterior 2x4 stud walls. 3) Interior A & B were alternate ideas; but if I need to use plywood for structural integrity, then A would be the only option. Because interior space is limited I do not want to build double stud walls. I thought using foil faced polysio on the interior side of the plywood would provide a thermal break, additional R value & space to run wiring (between horizontal strapping). To gain additional depth needed for electric boxes I thought about installing them horizontally on built out trim on (12-15” tall) baseboards. 4) I thought using the Dudley boxes would give the windows more strength and a surface to nail window trim to. 5) I wasn't sure if I needed a WRB due to the asphalt (asbestos?) siding. Considering your note about sealing window flanges to siding I am thinking it would be easier to install house wrap on the exterior and then seal the windows to that. Thank you once again for any thoughts/ comments.

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