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Should spray foam be used on the bottom of a newly installed window?

suect | Posted in General Questions on

Last year we had Marvin wood clad windows installed.

The sides and top of the external part of the window were taped, bottom left open.  The inside was spray foamed on all 4 sides, silicone and backer rod to all areas prior to trimming out.  Noticing a chemical smell and musty odor. Trying to locate the source.

Should the bottom have the spray foam?  If so, should the outside bottom be sealed like the sides and top?

There is a 1 inch opening on the bottom corners to the outside for venting.

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  1. creativedestruction | | #1

    The outside of the sill needs to remain unsealed for drainage. The interior foam seal needs to remain for pressure moderation.

    From what you've said the installation sounds correct.

  2. suect | | #2

    Thanks for your reply. Would the foam potentially absorb any moisture in the sill that could lead to the odors we are experiencing?

  3. Expert Member
    Peter Engle | | #3

    The foam is unlikely to be the source of your odors. Chemical/musty odors are generally related to water damage. You may have water getting in somewhere that you don't see. The window install sounds correct, but there might be leaks somewhere else.

    1. suect | | #4

      It just finished raining and the smell has intensified. Would the roof be a possible source?

      I have been monitoring the temperature and humidity up there.

      Right now at 57-59%. Attic temp 68-70F.

      I have noticed ghosting in the ceiling.

      1. the74impala | | #5

        "I have noticed ghosting in the ceiling"


        1. suect | | #6

          Would ridge vents solve this problem?

          Could this cause Moisture issues below, such as In the walls and basement?


        2. Deleted | | #7


  4. Expert Member
    Peter Engle | | #8

    If you don't see any obvious signs of leakage, you're probably going to need to find a building shell expert locally who can perform an inspection and water testing if necessary. There are some engineers and home inspectors who specialize in this work. Some mold testing companies are also pretty good at finding moisture issues, since the two are always related. But you want to focus on identifying and correcting the moisture issues first, not testing for mold. If you can smell mustiness after it rains, you already know you've got mold. You just need to find out where it is and how that area is getting wet.

    1. suect | | #9

      Thank you, we will look into this.

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