View Full Version : Installing insulation in my basement ceiling?

dennis thompson
01-30-2009, 7:11 AM
Part of my basement is unfinished & unheated with the ceiling joists open to below & currently uninsulated , the floor above those areas in the house is much colder than the floors in the rest of the house. It seems to me that it makes sense to me to insulate the basement ceiling between the joists in the unheated part of the basement. The joists are open so installing insulation should be straightforward. Has anyone done this? Have any suggestions on how to proceed? "R" value I should use? I live in New Jersey.

Von Bickley
01-30-2009, 8:03 AM
I would install fiberglass batts. In SC, we are required to have R19 in the floor joist. You might need more insulation value than R19.

jeremy levine
01-30-2009, 8:43 AM
Yes do it, hit the owen corning web site, they can tell you the R value for your area. Just be aware I don't think you can have exposed fiberglass anywhere in you home ( and the paper side of any insulation go towards the "warm in winer area".

Greg Narozniak
01-30-2009, 8:50 AM
I am in Jersey as well. I started doing this in my basement. I went with the completely encapsulated insulation and my joists are 10" so I believe I went with either R19 or R25.

Whichever was closest to that thickness. Lay it in and stable the edges. Easy as can be.

Tom Godley
01-30-2009, 9:00 AM
I have insulation between all my floors/ walls - mostly for sound.

You still need to be careful to not let the basement get too cold or you can have condensation problems.

I second the encapsulated -- even the low itch is still too much.

JohnT Fitzgerald
01-30-2009, 9:00 AM
I assume it's an older home then. I'd suggest going for it. REpeating what Jeremy said, the kraft paper side goes to the "warmer in winter" side.

also, since it's an older home, I'd do a check on any of the wiring that might be covered to make sure the covering/sheating is not degraded, causing potential problems.

Bill Dunn jr
01-30-2009, 9:08 AM
Hi Dennis,

I would insulate with the thickest insulation you can use without compressing it too much (it will lose it r-value if compressed alot). Since this area of basement is unheated make sure you are not taking all ambient heat away from any water pipes that might be there.


Tom Godley
01-30-2009, 10:47 AM
If this is in any kind of a normal basement -- I do not see all that much extra bang for the buck for going more than R13 unless you get a great deal on something else.

A normal basement should still be sealed from air infiltration -- The largest energy loss in most houses. You are just trying to separate the temp zones. If any of this is bellow ground -- the need drops even more. Even a unheated basement is much warmer than the outside air.

Even with radiant heat under a framed floor I use R13.

.... really don't want to make a basement cold.

Now a craw-space is something else.

Chris Padilla
01-30-2009, 10:57 AM
I had open-cell spray foam put into my crawl space. I have to admit that it didn't make as big a difference as I was hoping for but it did make some.

Remember that hot air rises because it is less dense than cold air and conversely, cold air drops.

It is possible that there are other reasons the floors are colder than the rest of the house so think about it a little bit.

Still, the cost won't be too bad and if it helps even a little, it might make a big difference.

hank dekeyser
01-31-2009, 9:10 PM
Part of my basement is unfinished & unheated

OK- so is this area a full height basement space w/ cement floor ? If yes then I would recommend running at least a single heat run to this part of basement. (return also) Twofold - It will help to keep the floor warm (simply insulating the floor won't make it any warmer- just keeps the cold from creeping in) and the air movement to that part of basement will help to offset mold and mildew.
#1 cause of mold is stagnant air (IE: lack of air movement)

I would insulate the sill all the way around the basement. that is the space between the cement wall and the underside of floor above. This alone does wonders - I prefer spray foam installed by a professional (not the foam in a can junk) in this location as it really does a nice job of effectively sealing the most overlooked area of a house.

BTW I am a professional contractor / builder - in the trades all my life so , Yeah I know what I'm talking about. I wouldn't recommend anything I wouldn't (or haven't) done myself - best wishes