Energy Upgrades for an Old House
Hi. I am a carpenter and I just bought my first house, a 1939 farmhouse/cottage in central NC. The framing of the house is in great shape, as is the yellow pine bevel siding. There is no sheathing on the walls and the house has an attic and crawlspace. The only insulation is fiberglass batts in the ceiling. It has central gas heat and air conditioning.
I plan to do some relatively light renovation before moving in including refinishing floors, removing ceiling tiles and kitchen floor tiles, and painting interior/exterior. However, I am considering a number of other improvements that I may want to make initially or down the road including, removing 2 masonry chimneys that are no longer in use, raising the house to increase the crawlspace height from ~18″ to 3-4′, sealing the crawlspace, and removing interior wall coverings to insulate walls with air gap/rigid foam/fiberglass method. The interior wall coverings and original trim work is in good condition and so I initially had wondered about dense packed cellulose as a way to insulate walls without completely opening them up but from the comments I have read, this seems to be risky without a WRB, although I do have substantial roof overhangs (~16″). The windows are all single layer glazing, wood frames in good condition and I do not plan on replacing them.
I have come across a number of articles on GBA regarding renovations of old houses but just want to post some particular details of my situation and solicit any thoughts on general approaches to making strategic decisions about changes to the house functions as a system. While it is clear to me that at this time it functions poorly from an energy standpoint, it is also clear that it has functioned well for over 80 years as a structure in terms of managing moisture.
I would be grateful for any thoughts, questions, or references to particular articles or other resources to help me.
Mike
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Replies
Dense pack generally won't work, besides wall moisture issues you also risk having the old paint starting to peel off the siding. This is pretty much the only safe way to insulate these type of houses.
https://www.greenbuildingadvisor.com/article/managing-water-and-insulating-walls-without-sheathing
In warmer climates, insulating walls doesn't make a big difference in energy use since the temperature difference between indoors and outdoors is small. You can and still should if possible but that it isn't as critical as in colder climates.
What does matter is air sealing the house. Most of these older structures leak like a seive. This is partly why they lasted for 80 years without any proper moisture control details, all that air flow keeps the walls nice and dry.
All that airflow also means your AC is mostly cooling the outdoors, so sealing up the place should be your first priority, sealing and insulating your crawlspace is definitely a good start. You can look at the details of air tight drywall install, lot of it can be done even after the fact if you are taking out baseboards with a couple of cans of expanding foam and tubes of stretch caulk.
Thanks for the reply Akos!
I appreciate the advice to prioritize air sealing and have learned a great deal reading articles on it over the past couple of days. At this point I am thinking of starting with the low-hanging fruit of air sealing the ceiling/attic from the attic, air sealing around chimneys, and weatherizing windows and doors with weather-stripping of some kind. Later this year I am considering raising the house and building a new crawl space foundation which I would seal and condition. For now, I am going to defer on opening the exterior walls but if and when I do I will insulate with rigid foam according to the article you referenced. Am I correct that if done properly, and attention is given to seal leaks between framing members, this is an adequate air barrier or should I still think of installing drywall such that it will act as an air barrier?
Thanks again