# Fiberglass insulation in basement?



## pyper

There are a lot of resources online regarding insulation in basements.

I wish there was some consistency between them!

You can definitely use fiberglass in a basement.


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## nateshirk

Yes. SOOOO many different opinions. That's why I thought I'd try to get a little more specific advise. Or maybe someone else could at least tell me they did it with no problem, even though time will only tell the whole truth.

Is the paper facing considered a vapor barrier? Thought I read that somewhere.


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## Wildie

nateshirk said:


> Yes. SOOOO many different opinions. That's why I thought I'd try to get a little more specific advise. Or maybe someone else could at least tell me they did it with no problem, even though time will only tell the whole truth.
> 
> Is the paper facing considered a vapor barrier? Thought I read that somewhere.


 Search for ROXUL on Google. Its much better for insulating basements as it doesn't absorb moisture. 
Has a greater R value/in. than f/g also!


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## Gary in WA

Where are you located?

Will you be using foam board first? http://www.buildingscience.com/documents/information-sheets/5-thermal-control/basement-insulation

Seal the rims first; http://www.buildingscience.com/docu...arriers/critical-seal-spray-foam-at-rim-joist

Gary


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## nateshirk

GBR in WA said:


> Where are you located?
> 
> Will you be using foam board first? http://www.buildingscience.com/documents/information-sheets/5-thermal-control/basement-insulation
> 
> Seal the rims first; http://www.buildingscience.com/docu...arriers/critical-seal-spray-foam-at-rim-joist
> 
> Gary


I was trying to avoid foam board. I live in PA where we get all kinds of weather. I'll look into sealing the rim joist.


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## Gary in WA

This will get you started; http://www.diychatroom.com/f2/basement-framing-99632/#post620367

Gary


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## Jbyrd

When I finished our basement I used john mansville insulation I got from menards. The batts were encapsulated in plastic. They were actually made for basement walls.


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## Gary in WA

http://www.buildingscience.com/documents/information-sheets/5-thermal-control/basement-insulation

http://www.buildingscience.com/documents/digests/bsd-103-understanding-basements?full_view=1

http://www.buildingscience.com/docu...rol-for-new-residential-buildings?full_view=1

There is a lot of good info on basement insulation, try the white box above this page and hit "search" box...
No air gap, sill sealer under p.t. plate, ADA, fire-stop every 10' lineally, etc.....

Gary


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## nateshirk

Wow.. thanks for all the tons of info in those links, but my brain is too tired to read all that right now.

Basically, just keep all basement air from reaching the cement wall? And seal the rim joist?


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## HomeSealed

GBR's comments and everything on buildingscience.com are right on. This info *is* consistent among those who know proper procedures.


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## Jackofall1

Jbyrd said:


> When I finished our basement I used john mansville insulation I got from menards. The batts were encapsulated in plastic. They were actually made for basement walls.


Depending on where you live you may be posting back in a couple of years on how to do mold remediation. 

You really should check out building science, they have the right stuff, developed by both solid engineering and lab testing.


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## Jackofall1

Powerup26 said:


> Fiberglass is fine, every builder ive worked for uses the fb insul on the basement walls and also for finished basement walls. If your house is properly sealed on the outside foundation then you shouldnt have a prob with moisture.


I every builder jumped off a bridge would you follow?, you really do need to do some solid research.

Mark


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## Jbyrd

Jackofall1 said:


> Depending on where you live you may be posting back in a couple of years on how to do mold remediation.
> 
> You really should check out building science, they have the right stuff, developed by both solid engineering and lab testing.


Actually 6 years later and a 125 gallon saltwater tank later no problems here.


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## HomeSealed

There is a right and a wrong way to complete any project. Recommending a method just because you have personally not had any issues with it does not make it correct and is irresponsible. I've seen roofs with 5 layers of shingles that looked nice and didn't leak, shower tile installed on drywall that looked nice and didn't leak, and windows installed with no flashing or insulation that looked nice and didn't leak... That doesn't make any of those methods proper, and should be avoided at all costs, just as framing or fg insulation in direct contact with a foundation wall should be avoided at all costs (even if it is wrapped in plastic).


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## Jackofall1

Powerup26 said:


> Sounds like a bunch of bs to me. Everything you listed is a leak hazard. There no way all that isnt leaking by now. Where does it say you cant put fb on a basement wall?? No one was talking about framing,as yes framing should be offset and also done in pressure treated


Firstly it's not a problem with fiberglass per say, its a VB problem, putting plastic on a subgrade basement wall is a no no, especially in the northern climates and shouldn't be done. 

Framing with PT is not necessary, the only PT needed is the base plate, if you are protecting against moisture damage by framing a basement with PT you already have a moisture problem or you have created one by putting plastic on the wall.

Mark


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## Jackofall1

Powerup26 said:


> Sounds like a bunch of bs to me. Everything you listed is a leak hazard. There no way all that isnt leaking by now. Where does it say you cant put fb on a basement wall?? No one was talking about framing,*as yes framing should be offset *and also done in pressure treated


Offset, what do you mean? an air space between the wall? if so.....not a good idea. 

Leaving an air space will create an opportunity for convetion loops which will undoubtedly cause a moiture issue and defeat the little effectiveness of the insulation.

You really should look at the attached

http://www.buildingscience.com/documents/reports/rr-0202-basement-insulation-systems

There really is a right and wrong way of doing the job.

Mark


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## HomeSealed

Powerup, your use of "fb" is confusing. Are you talking about fiberglass (fg?) or foam board? You can put foam board (XPS) on a foundation wall:yes:, you cannot put fiberglass against a foundation wall:no:.... The point of my earlier post examples is that YES, those are all disasters waiting to happen, and so is putting fiberglass directly against a foundation wall. Everything might look fine and dandy after 6 or even 10-15yrs, until you rip it apart for some reason and find a bunch of mold, nasty fg, and deteriorating framing. Then you wonder why your kids have allergies, etc... Please check out the numerous links to buildingscience.com . It explains everything in great detail and is practically irrefutable. Specifically the last link above is perfect for this discussion. Here is one excerpt "Any interior basement insulating wall system must have the
following properties:
• It must be able to dry to the interior should it become wet
since the below grade portion of the wall will not be able to
dry to the exterior during any time of the year. This
precludes an interior polyethylene vapor barrier or any
impermeable interior wall finishes such as vinyl wall
coverings or oil/alkyd/epoxy paint systems.
• The wall assembly must prevent any significant volume of
interior air from reaching the cool foundation wall. Thus it
must have an effective interior air barrier or a method of
elevating the temperature of potential condensing surfaces
(such as rigid insulation installed directly on the interior of
concrete or masonry surfaces).
• Materials in contact with the foundation wall and the
concrete slab must be moisture tolerant; that is the
materials should not support mold growth or deteriorate if
they become wet. However, moisture tolerant materials are
not necessarily capillary resistant. That is, some materials
may tolerate being wet without blocking the passage of
liquid water through the materials. A capillary break must
be placed between these materials and moisture sensitive
materials."

...I'd also highly recommend thorough review of page 13.


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## HomeSealed

The problem is, this is actually a very complicated issue. Groundwater is not the only thing that creates moisture in a basement. Are you familiar with condensation? Are basement walls cold? ..... Cold basement walls, interior moisture, and products that are not resistant to it = problems. Instead of just criticizing the links, why don't you actually read them and learn something... or if you still disagree, perhaps you can articulate why these PHD's who have dedicated their lives and careers to building science are wrong, and you are right.:huh:


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## pyper

HomeSealed said:


> GBR's comments and everything on buildingscience.com are right on. This info *is* consistent among those who know proper procedures.



The one article GBR links says to not leave any air space between the insulation and the foundation wall. Another says that without an air space you'll get mold behind the insulation.

To me, that's inconsistent. 

It's great that _you _know the proper procedures, whatever they are, but for us starting from scratch and reading the articles, there is a lot to puzzle over.


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## HomeSealed

pyper said:


> The one article GBR links says to not leave any air space between the insulation and the foundation wall. Another says that without an air space you'll get mold behind the insulation.
> 
> To me, that's inconsistent.
> 
> It's great that _you _know the proper procedures, whatever they are, but for us starting from scratch and reading the articles, there is a lot to puzzle over.


If you read very carefully it is not inconsistent at all. There are several products and methods discussed. To be fair, these articles are written assuming that the reader has a basic understanding of building science, physics, and construction knowledge. Please don't take that as an insult, I'm just saying that yes it can be difficult for somebody starting from scratch to decipher.... The proper method when using _interior _insulation is to apply the foam board directly to the foundation wall in order to keep it warmer. You can then add your framing, fg, and sheetrock.


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## HomeSealed

Powerup26 said:


> Yes condensation can cause mold, thats why you dont use plastic. Dead air space isnt going to cause mold in a wall. Ive never had a mold prob. In my dead space wall areas. You maybe thinking about an attic without proper air movement(venting). Fiberglass is fine attached to the wall this guy is just trying to push a product


It is not "dead air space" unless it is completely sealed, so that is not a valid point. Condensation still occurs with or without the plastic... If you refuse to read the article I guess that's your choice. I just feel sorry for the person that buys your home, or the homeowner who takes your advice, or your clients -- if God-forbid you are a "professional". 
... and who are you inferring is trying to "push a product" by the way? Myself or the other professionals who recommend that people inform themselves with a *FREE* resource such as the website linked above? ... or are you saying that the website itself is trying to push a product, even though they speak of all of the materials in generic terms? :wacko:


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## HomeSealed

Okay, seriously, are you just messin with me now? Am I on a hidden camera show or something??? .... I see that your other posts are all about electrical work, so I'll assume that you are an electrician. What if I started posting in the electrical section telling people to do some stuff that is a total fire hazard, and then when you and others show proof of the proper way to do things, I'd just stick to my guns and refuse to even read the evidence... What's that super-old electrical wiring called? Knob and screw, or knob and post, or whatever? Ya, that's what I'd recommend, because I've seen it in 100 yr old homes so it must be good, right? After all, it has lasted that long. That is what fg insulation against a basement wall is. An totally outdated method (that yes was considered correct once upon a time), until far better methods were figured out.... Since you won't go to the link, here is another important section:

"Full Wall Insulation with Foam
Sheathing Covered with Gypsum
Board
Either expanded or extruded polystyrene insulating sheathing
can be attached directly to the foundation wall. Since extruded
polystyrene is more moisture tolerant it should be used if there
is any question about the effectiveness of the external drainage
system (Figure 13).
If additional insulation is desired, cavity insulation can be
installed in a frame wall built interior to the foam insulation
and covered with 0.5 inch gypsum board or other thermal
barrier (Figure 14, Photograph 8 and Photograph 9). If no additional
insulation is desired, furring strips can be attached to the wall
through the foam insulation and gypsum board attached to the
furring strips.
Extruded polystyrene should also be used if an internal
drainage system with an interior drain is installed as shown in
Figure 15. All joints between pieces of foam insulation should be
sealed with mesh tape and mastic to prevent air leakage that
would permit warm moist air to condense on the cold
foundation wall. This approach has proven to be effective as a
retrofit strategy.
Existing concrete wall
2" XPS rigid foam insulation
(unfaced) tape all joints - adhere
to foundation wall
2x3 24" o.c. wood stud wall attached to
floor and floor joists
1/2" gypsum wall board; hold up from floor
1/2" minimum
Capillary break
Remove/replace with new 18" of existing
concrete slab for reconstruction purposes
(2) layers 1/2" plywood - mechancially
fasten first layer to slab; second layer glued/
screwed to first layer
1" XPS rigid foam insulation (unfaced)
tape all joints "


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## HomeSealed

Powerup26 said:


> I know what dead space is, and I know where its located in my house. I dont build houses, ive picked up on tons of things working in new homes being built by builders. Ive seen fg insul put on basement walls with no prob and guess what the building inspector has never said anything about it. Just plain old fg insul anchored to the foundation. No plastic,no foam board. Haha and the basements were quite warm even the cold months. Im talking about no finished basement here,no walls,heat registers,ect. Just a sheet of insul on the wall. Whats your article say about that??


... and to answer your question, it is once again completely irrelevant to this discussion. Obviously your scenario would create a warmer basement, but that doesn't mean that it wouldn't create other problems... That's my last comment on this. My primary reason for posting on this was so that unknowing consumers would not follow your poor advice, and I think that's been accomplished.


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## HomeSealed

uuuggghhh... Its been explained multiple times man. Yes a properly waterproofed basement with proper drainage, etc. will seal *out* water, but there is also moisture produced on the interior of the home. This moisture goes though and around the sheetrock and fiberglass to condensate on cold foundation walls, creating issues. Does that make sense to you at all?? ... It is great that you see all of this stuff done during new home construction, but guess what I do? I'm the guy who comes in 8-10 yrs later and fixes all the crappy, improper work and builder grade materials that are failing. There is an entire industry of mold remediation that exists in large part because of improper building practices. Insulation and ventilation are two crucially important functions in a home, especially in new homes. Guys like the authors of those articles have been studying this stuff for years, and new home construction is just starting to catch on to some of it. Come back 5 years from now and tell me if you are still seeing fg installed directly against foundation walls. Here is a question, why do you think it is necessary to not have wood against the wall, but its ok for fg insulation? ... And no, because I've seen it done before is not a valid answer.


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## Jbyrd

So what's wrong with using mold and mildew resistant insulation and the same with sheetrock? I'm no pro here I just came to this site to share my experiences and read what others have done. Seems like to me everytime you share your experience someone else knocks you down and tells ya you Did It Wrong! Well its my house not anyone else's. Maybe its time to forget about this site. There are a ton of crappy contractors out there that take your money and a ton that are great!!! Just because you did something for 20 years don't make ya pro if your not good at it. As far as your insulation question do what feels right in your gut. Its your house......


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## HomeSealed

Jbyrd, I am almost speechless. Do what's in your gut? Really? Should a person have no sense of responsibility to the other people who currently live in his/her home or who will in the future?... If you want to do shoddy work on your own home, thats bad enough, but dont come here and give bad advice to people that are trying to research and learn the right way to do things, and then try to argue that its correct. Then when you are proven wrong, whine about it and complain that "someone else knocks you down and tells ya you Did It Wrong!".. Guess what? This is the real world, not elementary school. We don't all get an A for effort. There is a right way and a wrong way to do things... I know very little about plumbing and electrical (even though I've done more of it than most ho's), so guess what? I don't post about it, because I'm not an expert. Please just stop for a second and think about how important your home is as an investment. Do you want to go out of your way to research how to properly complete a project only to receive bad advice from someone who really doesn't know what they are talking about? I'd imagine not. So don't offer it... If there is an area that you have a high level of expertise, then by all means, answer people's questions. If not, just stick to asking them.


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## nateshirk

HomeSealed.... So I should rip all the framing out and start over? Doubt that's going to happen. Is there anything else I can do along with fiberglass to help? I will be conditioning the air, and If I have to, I can run the dehumidifier too. Now, after reading that article, it does say to keep the basement air from reaching the wall. So if I seal any and all cracks to prevent this, will I be ok? But the article also says the wall has to be able to dry to the interior. So sealing it all up tight would also prevent this.


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## HomeSealed

nateshirk said:


> HomeSealed.... So I should rip all the framing out and start over? Doubt that's going to happen. Is there anything else I can do along with fiberglass to help? I will be conditioning the air, and If I have to, I can run the dehumidifier too. Now, after reading that article, it does say to keep the basement air from reaching the wall. So if I seal any and all cracks to prevent this, will I be ok? But the article also says the wall has to be able to dry to the interior. So sealing it all up tight would also prevent this.


Ideally, as described, you want foam board tight against the foundation wall, followed by the framing, fg, etc.... *IF* you have the exterior of the foundation very well sealed and_* IF*_ you are vigilant about controlling the RH of the interior (running a dehumidifier, etc), you _should_ be _ok_... That being said, in my own home, I'd redo it unless everything ( including sheetrock, etc) had already been completed. If its already done, maybe you keep a very watchful eye and cross your fingers.


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## Jackofall1

nateshirk said:


> HomeSealed.... So I should rip all the framing out and start over? Doubt that's going to happen. Is there anything else I can do along with fiberglass to help? I will be conditioning the air, and If I have to, I can run the dehumidifier too. Now, after reading that article, it does say to keep the basement air from reaching the wall. So if I seal any and all cracks to prevent this, will I be ok? But the article also says the wall has to be able to dry to the interior. So sealing it all up tight would also prevent this.


Ok the framing is done and you said its an inch away from the wall, get yourself some 1" XPS slice it to fit between the wall studs, or remove 3 studs so whole sheets can fit in and slide them down the length, making it as tight as possible to each other. I know tough work, but the peace of mind will be worth it.

Then insulate with non-faced insulation, then cover with drywall or what ever you were planning on doing.

Or you could listen to the person who knows what he has seen and is not open to the plethera of information spelled out in this very thread. 

electrician bucking the experience of a business owner who works on solving the problems produced by doing things incorrectly, Phd's on the subject of building science, a couple of mechanical engineers.....hmmmm, who do you think really has the right information here.

Good luck on your project, please post some progress pic's as you proceed down th epath.

Mark


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## nateshirk

OK. Say I decide to squeeze some foam board in. What do I do in areas where it can't be placed against the wall? Like the sewage pipes coming down and across the basement? Mounted directly to the wall. And the Electrical box is mounted to plywood, which is mounted to the wall. Just cut to fit around it then seal as much as I can? Or is it not worth the effort if I can't get a tight seal on the enitre basement wall?


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## nateshirk

Powerup26 said:


> Who built your house?


Brentwood Builders, in Central PA


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## HomeSealed

Mark's suggestion is a good one. Squeeze the foam board back there, get it as tight as possible to the stuff that's in the way, then fill the gaps that are left with expanding foam.... If that (pic) is the state that your project is currently, I'd definitely make sure to get the foam board back there one way or the other. Its just a matter of which method is easier to do so.


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## Jackofall1

nateshirk said:


> OK. Say I decide to squeeze some foam board in. What do I do in areas where it can't be placed against the wall? Like the sewage pipes coming down and across the basement? Mounted directly to the wall. And the Electrical box is mounted to plywood, which is mounted to the wall. Just cut to fit around it then seal as much as I can? Or is it not worth the effort if I can't get a tight seal on the enitre basement wall?


Yes just do the absolute best you can do and then seal with expanding foam.

Mark


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## Jackofall1

As Powerup has been witnessed by what builders do, once again the advice given is misguided.

As mentioned builders as in business to make $$, they are typically years behind the learning curve when it comes to doing what was done yester-year as opposed to what should be done today.

By his own admission, Powerup indicated that fiberglass insulation is not the best, and yet what do 98% of builders use?????? fiberglass, when by todays standards, cellulose is far superior and in most cases less expensive, builders take a long time to lose old habits.

If you do call the builder, which may not be a bad idea, to ask him if they installed XPS on the outside of the foundation, I doubt it, but if they did then you don't have to install any on the inside.

Mark


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## Jbyrd

HomeSealed said:


> Jbyrd, I am almost speechless. Do what's in your gut? Really? Should a person have no sense of responsibility to the other people who currently live in his/her home or who will in the future?... If you want to do shoddy work on your own home, thats bad enough, but dont come here and give bad advice to people that are trying to research and learn the right way to do things, and then try to argue that its correct. Then when you are proven wrong, whine about it and complain that "someone else knocks you down and tells ya you Did It Wrong!".. Guess what? This is the real world, not elementary school. We don't all get an A for effort. There is a right way and a wrong way to do things... I know very little about plumbing and electrical (even though I've done more of it than most ho's), so guess what? I don't post about it, because I'm not an expert. Please just stop for a second and think about how important your home is as an investment. Do you want to go out of your way to research how to properly complete a project only to receive bad advice from someone who really doesn't know what they are talking about? I'd imagine not. So don't offer it... If there is an area that you have a high level of expertise, then by all means, answer people's questions. If not, just stick to asking them.


As far as giving advice I never gave any advice to anyone, all I have said is what I did in my instance. Never to be used as advice. I am saying the argueing is ridicious. I have not argued with anyone nor ever called anyones work shotty or ho's. Yes I did uses FG in my basement and to date almost 8 years later no problems here. If I do end up with a problem guess I'll fix it then, and if I were to sell my house tomorrow I would tell the buyer it has FG. I take a lot of pride in my house as most others do to, but if you don't like someones advise keep the blows above the belt. Your adivse to date is probably accurate but in 10 years later it will done differently and be back at it again.


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## HomeSealed

Jbyrd said:


> As far as giving advice I never gave any advice to anyone, all I have said is what I did in my instance. Never to be used as advice. I am saying the argueing is ridicious. I have not argued with anyone nor ever called anyones work shotty or ho's. Yes I did uses FG in my basement and to date almost 8 years later no problems here. If I do end up with a problem guess I'll fix it then, and if I were to sell my house tomorrow I would tell the buyer it has FG. I take a lot of pride in my house as most others do to, but if you don't like someones advise keep the blows above the belt. Your adivse to date is probably accurate but in 10 years later it will done differently and be back at it again.


1. Ho's = Homeowners.
2. My reference to shoddy work was meant generally toward anyone who does not follow best practices
3. When you post the method that you used when somebody asks a question, that would qualify as giving advice.

.. Perhaps my response was a little harsh, but as I tried to explain, the folks that use this board as research take recommendations to heart. if you aren't certain that the way _you_ know is the correct way, it would be best not to share with others, don't you think? ... Finally, you are probably correct that there will be new materials and methods 10 years from now that will be superior to today's. That is called progress, and it is a good thing.


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## Gary in WA

OP, the information from BSC (most sites I listed) are the latest and are being incorporated (in part) in the current IRC 2009. 
Check around at different web sites to compare information on basement finishing. A few examples; http://www.terrylove.com/forums/showthread.php?41086-insulation-questions-and-help-for-my-basement

http://www.greenbuildingadvisor.com...ency-and-durability/18197/basement-insulation

http://www.familyhandyman.com/DIY-P...ent-framing-and-insulating/Step-By-Step#step2

Gary


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## daveblt

Homesealed... The advice you have given about insulating a basement ,does this refer to only below grade applications or both above and below.In other words if you have a walk out basement ground level above grade do you still need to put foam boards against the block wall so fiberglass can't touch it ? 

Dave


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