Re-insluating 1974 2×4 stud walls in northern Vermont
Three years ago we bought a 1974 ranch that had been converted to a cape with a “mini cathedral” ceiling in the living room that, no surprise, was as leaky as a barn. We had a blower door test done AFTER we had removed the garage door in the basement and replaced it with an insulated steel door, AFTER we had replaced the salvaged double-patio doors on the 2nd floor bedroom balcony that you could push open with one finger even when locked….and more – and the exchange rate was all of the air in the house every 20 minutes. When melt water from an ice dam came pouring into our kitchen one winter day, we paused the other renovation work being done to open up the (new) roof over the main area of the house to find old pink insulation that had clearly been soaked many times and reduced to an inch or so of material.
We had the roof there and walls that were opened up to install new windows spray foamed (closed cell). We have done a great deal of sealing and such, but the north wall has not been touched and I am certain it is the source of a great deal of draft that still comes through the house, especially on windy days.
I really don’t want to use spray foam again, given its environmental costs. But I’m having a hard time figuring out the best way to re-insulate that north wall – I am planning to rip out the wallboard and will do the work myself if it makes sense – but if I need a pro to install the insulation to get it done right, that’s fine too.
I’ve done a lot of searching, but I just keep reading about the problems with batt insulation (I thought I would go with mineral wool, but maybe not after all my reading….), air movement and moisture and thermal bridging. Unfortunately, the contractors I have spoken to either simply tout the insulation they install (foam, typically), or say something like “you need air in your house – don’t worry about it.”
Can anyone point me to resources that can help me figure this out or provide some advice?
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Hi knh1vt: if you have not already made contact with them, Efficiency Vermont provides lots of rebates, information, and access to specialized resources and contractors regarding Air Sealing:
https://www.efficiencyvermont.com/
Thanks, but I started with Efficiency Vermont and have been in touch with them again recently. I wanted to be fully informed from a few angles in case I have luck getting a contractor (they tend to be booked up).
Former spray foam contractor (VT) here - I am in a similar situation with a house that needs a "deep" energy retrofit in Maine...
What is the current insulation - FG w/kraft paper face or poly sheets?
My situation is a 2x4 wall with poly sheets & R11 FG batts.
FG batts without a Kraft paper facing are typically "friction fitted" into the stud bay, whereas kraft paper is sometimes stapled to the face or inside of the stud & the FG is glued to the kraft paper.
I am going to remove the baseboard & take off the bottom 2" to 3" of the wall board, reach in & pull the insulation out.
I am then going to purchase a DIY slow rise, pour-in-place, closed cell foam kit from Handi-Flow
https://www.energyefficientsolutions.com/Cavity-Fill-Foam.asp
This foam is specially formulated to cure slowly as it rises in such a way that it will not damage your sheet rock - they even tell you how long a "shot" of liquid foam should be administered thru a small hole in the wallboard based on 2x4 & 16"oc cavity.
"Application Shot Time - Pour in place (PIP) ONLY - The term “shot time” refers to the length of time necessary to dispense the desired amount of foam into the cavity or mold fixture.
• The shot time can be roughly estimated by first knowing the volume of the cavity (cavity size), and the desired in-place density of the foam.
• The following calculation shows how this information can be used to determine the approximate shot time in seconds.
WEIGHT NEEDED = DESIRED DENSITY X CAVITY VOLUME
• The actual shot time will also depend on other factors such as chemical temperature, application temperature, amount of chemical remaining in the system, etc., and can best be determined by trial application.
• In all cases, it is recommended to use weight of dispensed foam rather than the output estimation charts as these are only guidelines and are less reliable than the use of a scale to measure actual weight dispensed.
Then I will buy a FLIR One Pro LT iOS Pro-Grade Thermal Camera for Smartphones to watch that all of the bays are properly filled (as the foam cures it gives off heat as an exothermic reaction).
Our walls are 2x4 also. I’m not positive about the existing insulation- given what we saw in the areas we have opened up so far, I’m betting on pink insulation friction fitted, with no taping, sealing, etc.
Thanks for the info on the foam option, but foam is what I am avoiding. I’m pretty sure we’ll go with rockwool, taped and sealed with rigid foam board to stop thermal bridging. Maybe a membrane under that as well.
If I can get a contractor who will work with me, I want to do a fair bit of the work myself. I want to make sure everything is caulked or taped, etc. If we’re going to do this, it has to result in enough improvement to make it worthwhile.
You can simply dense pack over old fiberglass batts. You only need two holes in a wall, can be done without taking anything apart and doesn't involve any foam that could come back and bite you in the behind.
It could also be DIYed if you can rent a two stage blower.
That’s an interesting idea. I’m concerned about air leaks and thermal bridging, but the cost of ripping it all out to seal everything might not be worth it. Thanks for the suggestion.
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