Solutions for exterior insulation on home with poly warm-in-winter side?
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Home is in 4C or 5 (Clackamas County Oregon – DoE shows 5 on map, but lists marine 4 on county by county) and of mid 90s construction.
I am an interior decorator working for an HO with severe PTSD who will not allow any other tradesman near her home (I met her at a volunteer event for abused children), who has been having me do many different jobs on her home, which is in need of care. On some projects I am over my head, but she knows and is willing to compensate where I make mistakes. At least today it is not like in the days when you had to find an old salt in person willing to share – today we can all get access to expertise from those willing to share!
So a deck removal revealed the deck was thru attached to the sill plate, sandwiching original LP siding. Not a good find. After the siding is off, and the lower plywood, I advised we put the time into a rainscreen solution. She has requested Ledgestone but I am trying to keep her with siding – it appears by all measures to be less problematic (particularly as this home is over the Juan de Fuca fault line and her HO insurance earth movement policy precludes masonary veneers) and she has a limited budget – I am only trying to give her the most ethical solutions.
Adjacent to the gypsum there is dreaded poly sheeting. I have already decorated the interior walls with murals and plasterwork, and cant address it that way anymore.
On the exterior, there is 1/2″ CDX with approximately 1 thousand staples per sq meter. Its a nightmare to remove.
I need to insulate the rimjoist, as the crawlspace was previously encapsulated and is now part of the conditioned building envelope; furthermore the finished flooring is 2″ sleepercar T&G subflooring (found as well between the treated sillplate and the standard bottomplate) with no vapor barrier or other materials, and will create a lot of transmission to the exterior.
Q: Can I foam or even prime the edges of the sleepercar flooring to both seal it against endgrain moisture intrusion and prevent airflow?
Q: if I leave the poly sheeting next to the drywall, will I be doing her a disservice (ie, must I remove the plywood – its a 2 story tall building, hillside – cut out the sheeting and put new ply back up (or clip staple ends and use the same if its in good condition))?
Q: if no, and the sheeting is left in place, drying to exterior, it appears no rigid foam is suitable. Is this correct? The articles here suggested Roxul Comfortpanels as a solution but I cannot find them in small quantities (1100 sq ft of sheathing) reasonably priced.
Q: Any other advice you can provide about this situation that was not covered in these articles?
Thank you very kindly. I am doing my best to help this terrified lady to keep the house she so depends upon in good shape, and trying to get good advice where I have little experience.
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