insulating basement condo

[sid]

Finishing the basement of a condo. I intend to insulate the outside walls, but do I need to insulate the inside walls ? (the walls between units), they are not cinder-block, they are poured.

Thanks

Sid.

[ransley]

How will you insulate outside and how well, concrete is a poor insulator , insulating both sides is best, with foamboard.

[willshak]

on 5/8/2008 9:37 AM sid said the following:

The outside of the basement is already insulated, with dirt. I insulated my poured basement walls with studs, insulation and sheetrock. The average year round temps down here, without any heat supply, is between 62-75º F. I do have the oil boiler and propane water heater down here, which supplies a little heat in the winter, and the house AC helps cool it in the summer, since cool air flows downward.

[ransley]

ondo. =A0I intend to insulate the outside

Dirt is not insulation, my freeze depth is 3.5ft, dirt transfers cold.

[trader4]

condo. =A0I intend to insulate the outside

de quoted text -

Here's my take on answering the question. The value of insulating something depends on the temp difference between the two areas. As Ransley pointed out, depending on climate, the outside soil temp can be quite low for at least a good part of an outside wall. On the other hand, for a condo basement wall that is shared with another unit on the other side, the potential temp difference will be less. A finished basement that is heated on the other side, would have about zero temp differential. An unheated one, maybe 15 degrees or so. Even if it's a shared foundation wall with no basement on the other side, the area towards the middle of that wall is going to have a lot less temp differential than an outside wall when it's 10 degrees out.

So, it's clearly less important to insulate than the other walls. However, if it were me, I'd probably just go ahead and do it anyway, as over the years, even a small difference can add up.

[sid]

condo. =A0I intend to insulate the outside

de quoted text -

I insulated the outside wall with 1" foam board. My thought is that my neighbors side of the common wall is heated to at least 60-65F. Do I really need a lot of insulation on common walls, even if they are poured ?

[HeyBub]

If the temperature on both sides of the wall is the same, what's the purpose of the insulation?

On the other hand, insulation may prove useful for noise abatement.

[sid]

Another question: Some of the DIY construction books show not studding out basement walls but just screwing up 2x2s and attaching wall board to them. Is this recommended or not ?

[ransley]

I thought you meant the outside and inside of one exterior wall, I wouldnt insulate an interior adjoining wall, just all walls that are exterior to weather. 1' foamboard depending on type is only R4-R7, thats not much insulation. in Zone 5, R- 40 is optimal for walls, but few can do it or afford it unless it is new construction.

[Joe]

What did your building inspection department tell you when you asked ? Better call them if you haven't, and then you'll have the right answers if your HOA gets snitty about the project. Good luck.

Joe

[Joseph Meehan]

Dirt does insulate and even the best insulators transfer heat (cold does not transfer, it is just the lack of heat.) :-)

In most areas the ground temperature evens out at about 4-5 feet.

[Joseph Meehan]

Normally you would only consider insulating between units to reduce noise transfer. that is usually not a problem if the wall is block.

[ransley]

OK dirt insulates, it sucks out your heat in winter, an insulated basement wall underground will reduce heating costs. Does dirt insulate better than stone or concrete, R value of stone might be 0.5-

1 R" im guessing here.

[sid]

Anyone have a comment about the use of 2x2s ?

Thanks

[Joseph Meehan]

You over estimated. It is about 0.25* as compared to wood at about .50. Of course when you consider that it is DIRT CHEAP, that's not so bad. The mud buildings in the American southwest use it because of both the price and the insulation value when you have walls several feet thick.

• It varies a great deal depending on the soil mix and the amount of water in it. It is also a good heat sink and will temper day-night changes very nicely.

[Edwin Pawlowski]

Anyone have a comment about the use of 2x2s ?

Thanks

******************

Even 1 x 2 is OK since they are only holding the wallboard and not structural. OTOH, I'd use 2 x 4 on the outside walls and insulated them.

[Edwin Pawlowski]

Joe

Why do you have to call the building inspector? None of their business if you frame and insulate your walls.

[Edwin Pawlowski]

Do some research and see how much heat is being lost to that dirt. It is not a very good "insulator" at all.

[BobK207]

Per Ransley & Ed..... dirt isn't much of an insulator (but better than concrete)

R values per inch

"dirt" ~.25 concrete ~.08 wood ~1.2 (depending on type)

In areas where the frost depth is substantial you'll have dirt temps up against your foundation wall in the 32F to 0F (or lower).

Heated spaces will loose lots of heat through soil contact. That's one reason why above ground well insulated spas / hot tubs are so much cheaper to heat than in-ground energy hogs.

Without decent insualtion on the basement walls you can lose a lot of energy heating the soil mass around the basement. How much depends on the local soil temps during the heating season.

cheers Bob

[ransley]

In cold climates with no insulation and dirt covering the basement walls it is a drain on the utility bill, single pane glass is 1R, imagine heating a glass house. I insulated my basement walls with 2 and 3" of R 7.2 foamboard, up to R 21, it helped dramaticly. Adobe usage is in areas that even today dont have heating equipment. OP will save alot by using more than 1" of foam. Logs homes are actualy fairly well insulated, wood is near 1-1.2R. A 12" log might be 16R