Update on 1930 house in Northern MA (fieldstone wall, insulating, heat pump water heater in basement)
Thought people might be interested in the outcome of various renovations on the 1930 house we bought almost 10 years ago. I will post some photos.
As I explained in my original posts the basement was cold and damp with a fieldstone wall. Since the basement is not accessible from the house and we like to store items like lawn mowers and garden supplies there, we elected not to make it part of the conditioned space. We sealed it up well but did not insulate the two-foot-thick fieldstone walls.
Here is some good news: insulating the sill and the ceiling of the basement with 2″ of spray foam, then adding another full 3 1/2 inches of rock wool covered in fire resistant poly to our ceiling, we have finally warmed up the first floor of our house. No more cold floors, no more moist air coming up.
People here feared that the added basement insulation would make the basement cold, like below 32 degrees, having no heat source at all. So far it looks like temperatures will remain the same as they were before the recent insulation. If they stay above 45 degrees it is best because otherwise, we are forced to switch the heat pump water heater to electric resistance heating. That makes it less efficient in December through March. It would be nice to keep it in heat pump mode or hybrid mode all winter. Having a better sealed basement, we finally may be able to do that!
This strategy has had an impact on our use of natural gas. The gas bill for the 6 coldest months of the year (using normalized 2019 natural gas prices) has gone down:
2017 — $796.23
2018 — $676.65
2019 — $528.30 (Oct. 20-April 19)
2020 — $455.60 (October 20-April 19)
During that time we added a minisplit to the first floor as well as a remote thermostat. Right now it is not the primary source of heat but it does help us adjust the temperature when the house is uneven. During weekdays it is usually turned off.
We won’t be able to measure the full impact of these changes until March 2020. That will be a full year after the last insulation layer was put in.
*Still needing repair are the gaps in the first floor siding that let some cold air into the first floor walls and ceiling.
Here is my original post:
a couple of photos from 2018:
(1) example of floor joists replaced and supported prior to the spray foaming of basement ceiling. About 10 joists were replaced or added.
(2) photo of replacement sill. Before jacks were removed, rocks were wedged under it and mortared in place by a stone mason to support the weight of the house. The sill was later covered with spray foam.
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