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M_Portiss 02-05-2008 12:12 PM

Cold Basement! Please Help!
Hey guys... Long time lurker, first time poster. I finally got around to making an account recently...

Anyway. I am looking to warm my basement up. We have central heating, however there are only 3 outlets in the basement. (The main level and basement are the same size. 1600sq/ft per level) We just had insulation blown in our attic to get us to R50. A huge step from the 4" that was there.

When we had our energy inspection, the auditor mentioned insulating our headers (band joists) in the basement would really help in keeping the basement warmer. Right now it is COLD. I mean very cold. It seems colder since we had the insulation blown in. (Seems like it makes sense because the heater is turning on literally 60% less often)

Now, my question is would insulating the headers (band joists) get me in the right direction? I found a picture online that helps with my less-than-great description.


Thanks all

jogr 02-05-2008 01:56 PM

Yes absolutely that will help. My personal preference is to cut foam board and foam it in with great stuff foam. Two layers of 2" will get you R20. The cutting of the foam is a pain and messy but the long term advantage is that it virtually eliminates the chance that you will get wet moldy fiberglass from condensation. Fiberglass with a vapor barrier can work but I like the foam.

Are your basement walls insulated? I would try to get at least 2" of foam board on the walls to at least below the frost line.

All foam will need to be covered with drywall or some other approved fire barrier.

You need more registers in your basement too. The good news is that since your furnace runs 60% less it probably has plenty of capacity to heat the basement too. You just need to get the heat there with more registers and maybe an additional return.

concretemasonry 02-05-2008 03:26 PM

Cut your layers of foam to fit.

Use expanding foam to seal all of the cracks around the band/rim joist and then insert the pre-cut foam into the area between the joists.

The foam will expand, seal the infiltration and hold the foam securely in place. Place the second piece of foam later.

M_Portiss 02-05-2008 03:26 PM

First off, thank you for the quick response(s). I have already begun with r13 fiberglass, however. I have been double layering in the joist, and covering with 6mm poly. Then, I have sealed the openings with the red tuck tape. (Stuff is not cheap!)

The main line for my HVAC runs right down the middle of the basement. It has been completely covered with that cheap "woodgrain" board. It had been suggested to me to just cut holes about the size of registers and place the registers in the slots. The radiant heat would "seep" out into the basement and heat it up a touch. But, as you also suggested, I believe I am going to just add a few more registers off the main line.

Excuse my ignorance, but where might I find a place that would explain adding another return line?

There is just so much information on this site, I have trouble finding time to read it all.

Thanks again

***EDIT*** Is the foam really that much better than the Owens-Corning fiberglass? If so, why is that? Thanks again.

jogr 02-05-2008 04:49 PM

You can probably get the return info right on the HVAC section of this forum. If your furnace is already in the basement you may already have a return air duct grill in the basement. If your basement door is always open and the basement is not walled off into a bunch of rooms then you might find that you can have a comfortable basement without a return down there.

There are lots of opinions on where to place registers and return ducts (and how many/how big) and it will also depend on how many rooms and doors are going to be in the basement. For me I would rather start with minimal changes (aka least $s) and see if that works for my needs.

Foam blocks airflow better than fiberglass and will eliminate the chance of condensation in the fiberglass. But fiberglass can work fine and if you are taping up a good vapor barrier like you described then I don't think you'll have a problem.

M_Portiss 02-05-2008 06:15 PM

I cannot find a return air duct in the basement, so I will have to assume I do not have one. The door to our basement is always open, and there are really only 3 rooms down here. My office is about 8x8, and has one register. The "common" area is 32x12. (It only has one register) There is an "L" shaped laundry/workshop as well that is about 16x8. (Once again, one register)

So, would 3 registers in a basement the size I have described be very detrimental? Putting things into perspective, I would believe so.

I know this is not the "overly-scientific" way to describe this, however we have VERY good air pressure coming out of the registers in the house, so I would doubt adding a few more would hinder the heating abilities.

(Looking it up now, I have a Lennox C33-18A-2.. Doing a google search gave me these specs:)

1.5 Nominal Tons, 18000 Nominal Cooling Btu/hr --- OPTIONAL EXPANSION VALVE KITS - CHATLEFF STYLE, Refer to Matched Remote System ARI Ratings tables in Product Catalog - Air Conditioners Tab Section or Heat Pump Outdoor Units Tab Section for, specific matches.

Now, with all of that said, I have no idea what that all means! LOL

After I do the insulation, I am going to re-evaluate everything, and go from there. However, it is looking as though I am going to add 2-3 more registers in the basement for sure.

I am very anal about how I do home repairs. I am making sure 100% that the vapor barrier is VERY airtight.

Opinions? Ideas?

Thanks again for the information!!

concretemasonry 02-05-2008 07:01 PM

Fiberglass does not "absorb" moisture, but it will hold moisture and will not dry out unless it is removed. A small amount of moisture can cut the insulating value in half. The moisture is great fo mold growth.

Air infiltration is also a problem with fiberglass.

You can alway stuff in fiberglas (with reduced efficiency). If you are talking about ceiling insualtion, cellulose is far better, and is better for fires.

M_Portiss 02-05-2008 07:03 PM

I guess I should have mentioned that I used the crack caulking stuff like mad before I started today... I sealed all of the meeting points from the floor joists and the band joists.


M_Portiss 02-06-2008 06:14 PM

Update pics!


After: (Before Vapor barrier)

I have stuff r-13 three layers deep making sure I have not squashed it. I honestly feel as though the basement is warmer already. I am 85% done with the entire basement, but I am stuck on one thing. (I have made a thread looking for some help with that here.

Thanks again for all the help! I cannot wait to finish this project up and start my next one!


gregzoll 02-11-2008 09:54 PM

The Vapor Barrier should run up to the Ceiling and down the wall. Problem is with Basements, is the only way to run Vapor Barrier properly, is to have a helper, and pull it up to the floor above, and if finished, it is a waste. Use the acoustic tiles that are made of dense Fiberglass, and skip the Vapor Barrier.

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