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Community and Q&A

Replacement windows, siding or both?

doczjaz | Posted in Energy Efficiency and Durability on

We have a 1993 vintage small ranch modular home in New England. Climate zone 6A.  The windows (good quality Anderson double pain for then) are beginning to get very drafty, in fact the house does not seem to retain heat in winter (or stay cool in summer) as well as it used to. (Or we are getting old and thin blooded)  We have vinyl siding with, I assume, foam board underneath. I do not think Tyvec wrap was used at that time.  House basically sits in an open field and is in the sun/wind.
1. Does foam board have a life expectancy? Become less efficient over time?
2. Hubby wants to replace just a couple of drafty windows. We are using thermal blinds on a couple which helps.  Would that be penny wise?
3. Siding looks OK from a curb view (white) but there are some gaps, corners are not staying put etc. Should we think about replacing /upgrading for efficiency? If so replace insulation board and add wrap?
4. Would an energy audit be helpful? We have a new furnace (forced hot water heat) and mini split air conditioning and have insulated basement.  Most of the audits come with a company that wants to sell products.
5. If we decide to redo siding and insulation, should we redo windows….all or just leaky ones in rooms we use most often?  Just have them resealed?

Thanks for any information or suggestions.  We are not rich, but do not mind making good investments in the house.

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  1. Expert Member
    Akos | | #1

    Best to get an energy audit with a blower door test done before you start anything.

    Usually in older but decent modern windows, it is the framing around the window that leaks air not the windows themselves. A blower door test would show you where your windows are leaking. If it is just the rough opening, you can remove the interior trim and spray foam around the perimeter to air seal.

    Foam does loose a bit of the R value over time but not enough to matter. The bigger change is that it shrinks. If the foam was not taped when installed, this shrinkage could create big enough gaps that you can get a lot of air leaks especially if the sheathing underneath was not detailed as the main air barrier.

    Again, hard to tell where the issue is without a blower door test. If you see a lot of air leaks around your baseboards it is a good sign that either your sheathing or rim joist area is leaking.

    My guess a decent energy efficiency contractor can get the house back to near original with a bit blower directed air sealing without major siding or window work.

  2. Expert Member
    BILL WICHERS | | #2

    What kind of windows? Double hung? Casement? Something else? If you think it’s the windows leaking, it’s probably just bad gaskets which are usually replaceable. That might be a much cheaper option for you than replacing the entire window. Double hungs are especially prone to problems with gaskets and weather stripping.

    Next is to check around the window framing like Akos suggested. Canned foam can work wonders here, and sometimes caulk.

    Foam board does age, but it eventually stabilizes with a slightly lower R value than it had when new. Foam board doesn’t generally fail outright unless you have a critter problem (mice chewing it, ants burrowing in it, etc). I wouldn’t assume you have rigid foam insulation behind your vinyl siding, either. You might, but there is no guarantee.


    1. doczjaz | | #3

      Double hung Anderson and one casement Anderson. The casement is in the kitchen over a sink and the whole corner seems cold in winter. A cabinet in the corner is like a refrigerator when the wind blows. That's what made me think siding/insulation.
      Would an energy audit find the locations that have leaks?

      1. Expert Member
        BILL WICHERS | | #5

        A blower door test with a smoke stick will find air leaks. Infrared cameras can usually see bad leaks too. Really bad leaks can be found with the back of your hand (which is usually more sensitive to temperature than the palm) on a windy day.

        It will be worth doing the blower door test and going around with a smoke stick (that’s the part that locates the actual leaks) before you start ripping things apart. This is known as “blower door directed air sealing”. You don’t need to do a full energy audit, just the air leak testing part.


  3. user-723121 | | #4

    What about the foundation, could this be one source of discomfort?

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