Old house insulation, vapor retarder & ventilation
Having read your articles for years, I want to confirm my understanding of the literature with you, as we proceed with a remodeling project in our 1897 home in south/central eastern Iowa. Our balloon construction house has more than 6400 sq ft of living space, with gambrel style roofs on three sides. There is no soffit for ventilation, except near a bay window covered with a low, flat almost turret roof. There is no insulation in the rest of the house.
We are trying to renovate our third floor. It is 1900 square feet of 3rd floor space, with knee walls throughout, no soffit for ventilation. The attic above has gable ends which we can close with windows or open with louvred vents on the east and west ends. Our HVAC team placed our ductwork mostly in the unconditioned attic some years ago. I had requested that it be sealed properly, and it is triple wrapped with foil (R 9?), taped and now buried in R 49 blown in fiberglass.
Our contractor air sealed penetrations with foam as best he could, (though clearly we are not air tight and probably never will be). Then, he insulated yesterday, placing R49 blown in fiberglass in the attic and on one small, low, flat turret area in the third floor. He also placed R 13-19 friction fit in the stud walls, depending on the stud space. The contractors stapled 6 ml polyethylene over all the sloped ceilings and exterior sidewalls. Unfortunately, we cannot say that we are well air sealed. The drywallers are coming this morning to begin hanging the drywall they just delivered.
I would like to remove the polyethylene over the sidewalls and sloped ceiling, and instead use a Vapor Retardant paint with a perm of 0.45 to less than 1. Would that be the right thing to do?
Do you recommend we leave the gable vents open from April through October and closed with glass in the winter, OR should the gable vents be open year round?
Do you have any recommendations for specifics on air sealing our old house? I know this is a huge issue but many folks don’t seem to even
attempt to air seal these old homes.
Are there any specific articles I can read about the outcome of using this polyethylene in southeastern Iowa in an old house that is not well air sealed? All I have read on your web pages and my gut tell me to get rid of it.
Our old house has been breathing a bit too well for more than 119 years now. I feel the plastic is a huge mistake. Our hope is to keep this old home standing for years to come for the community and future families. Thank you very much for your help with my question.
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