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I bought an old house last Summer. There is a 8'x12' addition that bumps out from the kitchen, overhanging the back yard. The floor joists are exposed and there is some old insulation stuffed up there. That insulation gets blown around constantly when we get wind, so I want to close it in. Is that a bad idea?

I am planning to rip out and toss the old insulation and let everything air dry for a few hours. I was thinking it would be a good idea to take some preventative measures for mold before installing new insulation. I was thinking vinegar & peroxide solution in a spray bottle. Then, I am planning to cover the insulation with some Tyvek wrap to close in the space.

Is this a bad idea to close it up like that? Will that just facilitate mold by limiting airflow? If I do spray down with vinegar solution, how long will it need to dry before covering it? I ask because we are in a stretch where we get few, if any dry days. So I am hoping to get it done in <24 hrs.

Worth noting, we have a renovation coming up on that addition to resupport it and an attached deck. So we can come up with a more elegant solution then. This doesn't have to be perfect.

Pseudonova
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This sounds a lot like the many three- and four-season porches I built when they were popular add-ons to suburban homes in the 90s and early aughts. (Maybe they still are.) My current home has the same.

Our usual strategy was as follows:

  • Standard white (untreated) joists and wall sheathing
  • House wrap on the walls and underneath the floor framing
  • Treated plywood or vinyl/metal soffit under the floor framing, over the house wrap

This allows the system to breath while preventing water splash from encountering the framing or insulation. It also protects the house wrap and insulation from pests and other damage. House wrap has a limited direct weather exposure lifespan.

In your case, let things dry out as long as is practical. It can take weeks for lumber to substantially shed moisture. Then replace the insulation and seal it up as described above. All should be well.

I would not bother with mold treatments unless you can't brush away the majority of it with a whisk broom. Mold spores are always everywhere, and it's not really a concern once things are dry.

isherwood
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