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Discussion Starter · #1 ·
I have forced hot air and an unfinished basement. I have no supply vents in the basement, and as a result it is extremely cold down there. So cold, in fact, that the hard wood floors on my 1st floor are cold to the touch and probably makes the first floor cooler than it should be. I am wondering.. if I cut a few vents into the supply trunks and insulate the basement ceiling, will there be a noticeable difference? Also, will I negatively impact the heat being supplied to my first floor. My second floor has a separate unit. Can anyone help? Thanks
 

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You don't insulate the floor, you insulate the basement walls and headers.

Can add vents but add too many and doing so will negatively impact the first floor.

Basements don't need much heat if the air leakage and heat loss are taken care of.
 

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Discussion Starter · #3 ·
Thanks for your help. My plan, in the near future, is to begin finishing the basement. However, for right now, I was just looking for the proper way to address the issue of the hardwood floors being cold on your feet. I thought insulating between the 1st floor joists would help keep the cold air off of the subfloor.
 

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Thanks for your help. My plan, in the near future, is to begin finishing the basement. However, for right now, I was just looking for the proper way to address the issue of the hardwood floors being cold on your feet. I thought insulating between the 1st floor joists would help keep the cold air off of the subfloor.
Ayuh,.... You could do it that way, But,....

It'll work alot better by insulatin' the cellar, 'n includin' it in the heated envelope of the house,...
 

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If you're going to finish the basement, I suggest getting underway instead of stop gaps in the meantime.

Near same situation as us. I hung 6 mill plastic along the walls by rolling a few wraps around furring strips and driving tapco (?) masonry screws through the strips and into the wall. Then framed on 24" centers (non-bearing), wired for power, 4" fiberglass insulation and drywall. I laid 6 mill plastic on the floor sealed with 3M tape specifically made for plastic. Put underlayment on the plastic and a floating floor.

The plastic creates a vapor barrier and the insulation prevents condensation in summer high humidity.

I had replaced our hot water heater with a 75 gallon unit earlier. As I was finishing the basement, I noticed two plugged connections on the heater labeled "heat in" and "heat out". After some head scratching, I ran a loop of fin-tube along the two longest walls off those connections with pex pipe and domestic water circulator with an across the line stat. Despite everyone saying the water won't be hot enough to heat the basement, its the coziest place in the house.

I configured for a mini-split AC unit. Its been a couple years and the basement never went above 76 degrees even during the worst dog days of summer.
 

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1 or 2 small vents (4" of 5" round) would be the most i would put for the basement. That's all that warned my insulated, unsealed basement enough to have comfortable 1st level floors. Remember warm air rises, so it'll stay aloft against the basement ceiling until it cools, giving up the majority of its heat to the floor.

Cheers!
 

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I thought insulating between the 1st floor joists would help keep the cold air off of the subfloor.
It's not overly effective given the thermal bridging of the floor joists. Plus, it would make the basement even colder.

Get a bit of supply and return in there, stop the air leakage, insulate walls if they haven't been done and you'll have a warm basement + lower energy bills.

A chunk of the basement is above ground so heat loss can be very significant.
 
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