Managing Moisture and Insulating a Complicated Old House
Hello! My name is Jason and I’ve recently acquired an old summer home in MA (Climate Zone 5A). We’re considering making the building inhabitable in the winter. Key facts:
– Built in 1927
– 4,666 sqft
– Extremely large, unvented attic (sloped roof). Walkable throughout, floored, absolutely opposed to filling it with 10″ of loose fill and rendering it unusable.
– Built into the hillside. Soil is sandy loam and well draining.
– Multiple basements: One finished with boiler, heaters, etc with an accessible dirt floored crawlspace, the other a walk in but unfinished, dirt floored space, with the slope exposed, and a second crawlspace accessible.
– No insulation in any part of the home.
– Original 1927 cedar shake siding
– 2011 asphalt roof replacement with solar.
– 68 single paned, original wood windows.
Why did I just list all these facts? Well, everything I’ve studied on the subject of winterizing & insulation stresses the importance of considering the entire system of the home.
My struggle: Most advice you read focuses on solving one piece of the puzzle.
So far I’ve brought in some insulation contractors and also participated in a “Mass Save” evaluation (virtual thanks to COVID). Neither of these have inspired any confidence in me that they are considering the home as a system.
I apologize for making this a multipart thread and I know many of these subjects have been covered in individual threads and articles. My hope here is to find resources, advice, or referrals to help us tackle this home as a system.
Our goals for the home: (1) Do no harm. (2) Invest in the highest returns and work our way down until we arrive at an efficiency level we are comfortable with. (3) Get to a point where the home can be climate controlled.
Our current plan. Places marked with [??] I am uncertain on but welcome criticism/advice on any stage of the plan.
– Do something with the drafty old windows. Not really a question for this board but welcome any advice there.
– Keep current, unvented attic. Apply closed cell spray foam to underside of roof sheathing. Supplement with [??] insulation to achieve code R value and cover with drywall.
– Insulate rim joists with closed cell spray foam.
– (Mass Save recommendations): Apply vapor barrier to dirt floors (plastic sheathing). Apply [??] insulation to the basement ceiling then cover with a thermal barrier.
Primary concern here is the basement.
(Q1) The foundation walls are currently allowing water to seep in during heavy rains. Preventing this given the hillside will always be a challenge. If I cover the dirt floor with sheathing, won’t that moisture just collect on it? Should I also line the concrete walls with a vapor barrier?
(Q2) What is the right way to handle the insulation of the basement ceiling as proposed by Mass Save? I presume it is unlikely they will achieve a consistent vapor barrier, so I should be careful what insulation I allow to be put up there?
Second Step: Walls
I will be re-doing the interior walls on the 2nd floor of the home – replacing old lead painted paperboard with proper drywall. The rest of the home has has beautiful wood shiplap which I would like to avoid removing.
(Q3) While I have the 2nd floor open, I have an opportunity to insulate. Is there any safe way to insulate here?
Can I put some sort of moisture permeable, breathable insulation that won’t change how the home functions?
I’ve also seen a setup described here: https://www.youtube.com/watch?v=jhoQ_f9ZnzQ essentially creating an airgap and then an air barrier on the interior of the wall, then insulating behind that. Seems like a lot of work that could go wrong however.
(Q4) If all else fails, we’re also considering waiting on the walls until we re-do the siding. At that point we’d insulate from the exterior of the home. Is this just the right thing to do? Live with higher heating bills for a few years until we decide it’s time to spend the big money on redoing the entire exterior?
I welcome any and all advice & criticisms. Thank you in advance!
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