New Old Place - Random Questions

Started by rich2Vermont, April 25, 2018, 08:01:18 AM

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Hi - while we're never giving up our first place in Vermont (, we recently purchased our forever home, also in Vermont. It's a pretty well restored 1830's farmhouse. The previous owner took it down to the studs, added foam insulation everywhere, etc. He didn't do everything right, and I'll be fixing those things. My first question to the community is regarding the radiant heat that is installed for the first floor. This is perhaps 14 years old, but when they installed, they didn't use diffusion plates or insulation:

So, what is the best course of action here? Add some diffusion using foil tape, and then insulate below? Or something more regimented? Any advice would be helpful. Thanks!


I'd look into the reflective bubble radiant rolls in joist bay width stapled under the tubing and then insulate below that.


Thanks Don. Would the bubble stuff go right up against the tubing, or should there be a gap, or does it matter?


A radiant barrier works when there is an air gap, I'm thinking if it were against the bottom of the tubing and flat across that plane it would provide that gap as opposed to just mashing it up tight to the floorboards around the tubing. Then insulation under that. I'm no pro here just my personal opinion.


I don't think the foil will achieve anything. Also with an upward facing foil, as dust settles on it, it will stop being a radiant barrier. If the foil is touching the pipes it will conduct the heat but I don't understand the purpose of that.

The best thing to do is insulate the basement. It will save a ton on the heating bill, according to building science up to 1/3 of your bill. If you do that I don't think anything needs to be done with the tubing.


Spitballing here, but I'd give some thought spraying gunite over the pex to build some thermal mass, followed by spray on insulation foam.
My cabin build thread: Alaskan remote 16x28 1.5 story


Thanks guys. Appreciate the advice. While the basement walls are half insulated with spray foam now, we'll be having the rest done soon (hopefully). The main reason for that is so we can have effective radon mitigation, a problem the seller said he "solved" by opening the clean out door to the chimney. Yeah. Not. We want to avoid dying due to a colorless, odorless gas, so the we'll have the rest of the basement insulated. However, I still don't care to heat an unused space. But I agree that dust might be an issue, as it's a really old floor and you can see daylight from the first floor in some spots in the basement. So, I'm thinking of using foil tape on the underside of the floorboard gaps, and then going with Don's suggestion for reflective bubble wrap and then fiberglass. Thoughts?


This is a good article on foil.

By the time you finish insulating the basement walls I really don't think you will be able to tell a difference in your heating bill after putting insulation in the flooring.

I am less certain about this consideration - by insulating the basement walls and then also attempting to not heat the basement, the walls maybe be at risk of 'adfreezing.' If you heat the basement, there is no risk as the bond between ice and wall would be too weak.

Basing it off this article

"Unfortunately, upward frost heave can be a concern if the ground freezes against the foundation. We call this "adfreezing," which is short for adhesion freezing. The ground adheres to the foundation wall, and when it heaves upward, it will lift the wall with it. Except, it doesn't happen with heated basements, regardless of whether they are insulated. But, it does happen in
unheated basements if there is frost susceptible soil and available water. What gives?"