Is it too risky to remove basement ceiling insulation and insulate basement walls in a drafty basement?
Homeowner in Long Island. My unconditioned basement has concrete foundation on three sides and framed wall with sheetrock and insulation on the fourth side. There’s a sliding glass door and three casement windows. Geothermal hvac unit and ducts are in the basement but don’t give off much residual heat. There’s insulation in the basement ceiling.
I know everyone says to insulate the walls and not the ceiling of a basement but I’m wondering if that’s too risky. I plan to air seal and insulate the rim joists super well. I can also put thermax on the concrete walls. I’m worried that without any residual heat from the geothermal unit and with the sliding glass door and windows, it will be too risky to remove the insulation from the ceiling of the basement bc it will make the upper floors too cold. I’d rather not open up a return and supply duct to heat the basement since I use it only for storage. Any advice is appreciated!
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Insulating the walls will improve conditions in the basement, and you won't see cold floors. The other advantage is that the wall insulation tends to hold up better over time, whereas ceiling insulation in basements tends to fall out over time and perform less than optimally. I can't tell you how many times I've seen crawlspace and basement ceiling insulation installed "upside down", with the vapor retarder on the wrong side, too!
Sealing the rim joist will probably help a lot with drafts -- rim joists tend to be very leaky areas.
Bill
I recommend conditioning your basement with heat and humidity control. And cooling if needed. It doesn't need to be the same temperature as the main level but the warmer it is, the less chance you'll have of moisture-related issues. And without ceiling insulation, much of that heat will make its way upstairs.
Ok I’ll make sure to focus on the rim joists and do a thorough job with the wall insulation. Thanks, Bill.
Michael, as far as conditioning the basement with heat/cooling, it seems the only options are to open up both a return and ducting using the existing ducts in the basement or get a separate heating cooling/system just for the basement. One option causes mixing of basement air with air in the rest of the house and the other may be expensive. Let me know your thoughts!
Basement air won't be any different from indoor air if you insulate and seal the basement. This is the same as for crawlspaces: once you've done a crawlspace encapsulation project, the crawlspace's air is essentially part of the living space, and it's sealed off from the outdoors and from the earth.
Bill
Thanks Bill. I guess you are on board with Michael as far as heating and cooling the basement, even though I use it for storage?Trying to get as many perspectives as possible. My worry is the upper living levels get cleaned all the time but the basement doesn’t. Also there is just a concrete floor that collects dust. That’s all going into the hvac unit now if I open up a return in the basement
Yes. Once you air seal and insulate the basement, it's really within the building envelope, so it should be conditioned accordingly. Often you can do this with your existing HVAC system, maybe with a few additional vents. You usually don't need to do anything fancy. In my own home, the only thing I added was a dehumidifier.
Bill
Thanks bill. Final question. You just opened up some vents in your basement without installing a return? I thought you needed a return as well.