We have converted a three season porch into a four season by adding a gas stove and some new windows. Below is an unfinished basement - the joists and subfloor are exposed. Do I gain any efficiency by installing insulation between the joists?
Thanks in advance for any advice.
I would guess little to none.
Sure do. How much depends on the temperature differential. If the basement is only a few degrees cooler, there will be little savings, but if it is 20 degrees, you will retain more heat and save quite a bit. .
I'm in New England. At times, it's 50 degrees cooler.
Then you must insulate for comfort, as well as energy savings.
Underneath the three season porch is a seperate basement (attached to main basement via a door). There are no pipes or ducts down there and it's unheated. When it's 0 outside in Feb, it's probably not more than 20-30 down there. Pipes, furnace, etc, are in the main basement.
We have a natural gas stove that heats the room up in about 20 minutes. Gets it too hot.
I live in Mass..........
If it was me, I would tear out the deck flooring and install a subfloor with wood flooringon top of it..
But thats just me. But yeah, it would definetly be the wiser to install an insulation. Your floor would then be warm, not as cold as underneath. That would be terrible to have a warm room with cold feet. :-) Save some money too.
Thanks... I wasn't clear. We have a full subfloor/floor. It's not "deck flooring"
What I'm confused about...if heat rises and the basement is unheated and cold, why would the floor be warmer? Do I lose heat through the floor?
Now you're getting it. :')
Heat does not rise. Warmer air is less dense than cooler, etc., etc.
Heat is transferred by conduction, convection and radiation. You passed on the third.
Basic physics.
Oh ... and sealing is also extremely influential, and you don't mention insulation in the rest of the shell. Nowadays, moreso tomorrow, you can't have too much.
HTH, J
MathWhiz wrote:
Heat will move wherever there is a difference in temperature. Basically, heat flows from areas of warmth to areas of cold.
Many people believe that because hot air rises, most heat loss will be through the ceiling. This is not necessarily so. Heat moves in any direction - up, down or sideways - but always from a warm spot to a colder one. A heated room over an unheated garage or basement will lose heat through the floor. Similarly, heat loss can occur through walls in the basement or crawl space, as well as above the ground. Heat moves to the cold. It's the job of the envelope to control the flow of heat between the indoors and outdoors. To maintain our indoor environment, the envelope must control the flow of heat, air and moisture between the inside of the home and the outdoors.
Dean
If your basement is 30º F colder, I reject my original answer and suggest a good amount of insulation.
The question is how much, the best would be foam sprayed on of R7 per inch, second best would be an inch or two of R 7.2" foamboard then fiberglass batt, the least effective is just fiberglass batt of R 3.5. Your temp difference is great, foam will also stop air infiltration, which you dont detect but is happening.
I hope so, since my house has an unfinished basement, and the whole first floor has insulation in the floor joists.
The basement gets to low 60's in winter, and floor feels warm. So it must be working.
later,
tom @
Yes ... but if you ever plan to heat that basement below, it would make sense to insulate the basement walls now, rather than insulate the floor, and then the walls later. If not, insulate the floor ... if the floor feels cold as in, even wall to wall carpet with underpad would probably provide all the insulation you need. To continue, I had a similar situation with a hadwood floor ... I insulated the basement walls.
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