# Does the bottom half of basement wall has to be insulated?



## Johnny Ren (Dec 14, 2010)

My house builder just got upper half of basement wall insulated. I'm going to finish my basement. DO I have to get bottom half of the wall insulated also?
If he answer is yes, can I do the same insulation as upper portion before framing it?
Please see attached picture for details. 

Thanks!
Johnny


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## jklingel (Dec 21, 2008)

First, where are you? Second, what is the bottom half? ICFs of some kind? Third, why do you have poly on the upper half? That is a potential disaster waiting to happen, depending on where you are. I would suggest you spend some hours at buildingscience.com/resources and read a lot about insulating, esp in your particular environment. Good luck. j


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## MJW (Feb 7, 2006)

Insulate the bottom half using Thermax or something similar. That will bring it up to code. My guess is this house was built in the last 15 years, but not newer than 3-4 years. That pictures shows was use to be code compliant. The energy code changes almost daily.

Make sure to get a building permit and do things right the first time. Have every step signed off by the inspector.

BTW, you'll have to probably seal off that rim area also above the wall.


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## ccarlisle (Jul 2, 2008)

That's minimum building code for an unfinished basement, concrete wall - even for cold climates - in some jurisdictions I know, and is called the diaper method of insulating the uppermost part of a basement wall. 

This is acceptable for an unfinished room, but you'll probably remove all that if you convert that space into a livable area.


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## Johnny Ren (Dec 14, 2010)

Thanks for you reply!

To answer your question, I'm living in Toronto. The bottom half is concrete. The picture I showed you is original one, I didn't touch anything. it looks like that I have to remove existing insulation from the wall and re-do it.

Johnny


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## Johnny Ren (Dec 14, 2010)

Thanks for your reply!
You are right, the house is 20 years old. In order to save money, I want to keep the current insulation as is and add same material on bottom half. But not sure if it can meet up the code.
Okay, I will call a contract to inspect it first.

Thanks!
Johnny


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## Johnny Ren (Dec 14, 2010)

Yes, what you said is same as what I heard from Home Deport. But I really don't want to remove existing insulation and put new one on that because that will waste money.

Thanks!
Johnny


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## epson (Jul 28, 2010)

You can also do this: http://www.homeconstructionimprovement.com/how-to-insulate-basement-walls/


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## ccarlisle (Jul 2, 2008)

Yeah, I thought you were in Canada...that's our minimum code.

There are a number of reasons why that stuff should go if you are planning on insulating that wall corrrectly - but saving money on taking it down isn't one of them. 

For example, if you are considering going with the fibreglass-batts-under-a-plastic-vapour-barrier method, then you'll need studs to put the FG batts into and hang the wall covering, and an integral vapour barrier. So, none of what you have there in that picture is of any value in that scenario...

If you are planning on going first-class, then spray foam the whole wall. All that stuff - you guessed it - has to go. 

The correct way is to put on sheets of extruded styrofoam onto the concrete walls and floor, then studs. Stuff has to go.

It'll take you a minute to pull that stuff off, so do that just before you start on making it a liveable space.


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## MJW (Feb 7, 2006)

ccarlisle said:


> Yeah, I thought you were in Canada...that's our minimum code.
> 
> There are a number of reasons why that stuff should go if you are planning on insulating that wall corrrectly - but saving money on taking it down isn't one of them.
> 
> ...


 
Just a guess here, but I think that cement wall is all there is for cement. The 2x6 wall is behind that pink insulation. I bet there is batts inside the framing on the half wall and then another layer over all of it. All speculation, but that would be up to code and wouldn't have to be removed.

Like I said, Thermax would be your best bet and tape it with the foil tape. Use 1 1/2" minimum which would give roughly R-10 on that lower wall. Either way, you will have to make a vapor barrier inside, including the rim area.

Stay away from the big box stores. People work there for a reason. They can't hack it in the business. I would suggest someone who is familiar with up to date codes in your area like a Contractor or the building inspector. Not sure what the inspectors are like up there, but here they are very helpful to homeowners.


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## MJW (Feb 7, 2006)

BTW, Ccarlisle's suggestion would be the best, but more costly.


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## ccarlisle (Jul 2, 2008)

Up here, concrete basement walls like that are at least 8' high. They don't do 'half-and-half'...
:no:


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## MJW (Feb 7, 2006)

ccarlisle said:


> Up here, concrete basement walls like that are at least 8' high. They don't do 'half-and-half'...
> :no:


So, no split level housing in Canada? Hard to believe. Probably the most common house here.


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## ccarlisle (Jul 2, 2008)

Not sure I follow you; sure we have split levels, but the stick frame sits on top of a solid concrete basement foundation.

That's what the OP seems to have.


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## MJW (Feb 7, 2006)

ccarlisle said:


> Not sure I follow you; sure we have split levels, but the stick frame sits on top of a solid concrete basement foundation.
> 
> That's what the OP seems to have.


Split level houses have frost footings, then a half block wall or poured wall on that (usually around 38-40 inches tall), then the rest is framed up. That way you have something to nail siding to above grade outside.


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## ccarlisle (Jul 2, 2008)

Ah-ha, now I see.

I haven't come across that up here. Pretty well all houses have an 8' solid concrete foundation, for obvious reasons.

The type that the OP has is typical of houses _up here_, I am surprised they do what you describe in Minnesota.

Learn something every day.
:thumbsup:


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## MJW (Feb 7, 2006)

ccarlisle said:


> Ah-ha, now I see.
> 
> I haven't come across that up here. Pretty well all houses have an 8' solid concrete foundation, *for obvious reasons*.
> 
> ...


Why? Concrete doesn't have even close to the R value of an insulated wall.


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## ccarlisle (Jul 2, 2008)

It resists frost-heave better tho'.


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## MJW (Feb 7, 2006)

Not really. That is what your frost footings are for.

Maybe we'll get aresponse and better pics from the OP.


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## Johnny Ren (Dec 14, 2010)

MJW said:


> Not really. That is what your frost footings are for.
> 
> Maybe we'll get aresponse and better pics from the OP.


Hi, you guys are correct. The behind of the fiberglass is also concrete, so the total height is 8'. From what I understand from your discussion, I better to remove all existing stuff. then put foam board, then studs. It's really not what want. But if it's best solution, ....


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## ccarlisle (Jul 2, 2008)

Yeah, well it may not be the best solution technically, but it is one solution you must consider IF you are planning on converting that space to liveable space. Otherwise you don't really need to do anything.

You must also consider properly insulating the space _above_ that pink stuff, in between the joists, those square 'boxes' where the concrete meets the wood. A lot of heat escapes there...

So if you are going to convert that space, then you'll not want what's there anyway...it isn't doing much more than the minimum, which - in this day and age of doing more and saving more - isn't good.


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## Gary in WA (Mar 11, 2009)

Enjoy: http://www.buildingscience.com/docu...ing-hygrothermal-modeling-basement-insulation 

Heat loss below grade: http://www.quadlock.com/technical_library/bulletins/R-ETRO_Value_of_Basement_Insulation.pdf

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

Gary


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## MJW (Feb 7, 2006)

Johnny Ren said:


> Hi, you guys are correct. The behind of the fiberglass is also concrete, so the total height is 8'. From what I understand from your discussion, I better to remove all existing stuff. then put foam board, then studs. It's really not what want. But if it's best solution, ....


I see. I forget that back then the codes were much different than now. Still wierd how they waste all that cement above grade.

A foil faced foam would be best with a higher R value than the Dow, plus you won't need a vapor barrier over it.


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## jomama45 (Nov 13, 2008)

MJW, the Canadians had/have me confused on this one as well. I thought that it was a partial exposure myself, but now think it may be completely below grade and they only insulate the top 4 feet or so due to the extreme soil temps...........


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## MJW (Feb 7, 2006)

jomama45 said:


> MJW, the Canadians had/have me confused on this one as well. I thought that it was a partial exposure myself, but now think it may be completely below grade and they only insulate the top 4 feet or so due to the extreme soil temps...........


I think you are right. I read another post from a Canadian Contractor and he said they only have to insulate to 2 ft. below grade. Wierd. Since the IRC code (06, I believe) went into effect here, we have had to insulate the entire wall (R10 at least, in basements and rim joists).

Still confusing (if it's true) on a half basement (split house), why they would put up block 8 feet if only half is in the ground. Maybe I'm misunderstanding that one.

If it's a full basement, then I understand the picture.

BTW, many responses I see lately just relay to building science (or 'Green Building' page). Didn't know they made the codes. haha. That site (blog) has been around for quite some time now, and points out many key things that most good Contractors already know. Maybe there should be a sticky that says "if you have a question, just go to building science webpage (blog). 

No offense GBR, your posts are almost always links (that's a given), which is good, but it seems too many are just relaying links now.


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## Gary in WA (Mar 11, 2009)

Yes, the first link showed exactly what the OP has on his full height concrete (not cement) wall, and the good and bad about it from testing done in Canada. It wasn't meant for you, as you probably already know it all, as you said. 
The second link was showing the heat loss below grade and the savings in dollars. 
The last was commenting on the mold growth from plastic and also addressed the first as well as the heat loss below grade. I sometimes type more of an answer, when I have the time, but at least the Op can read the science as no one else offered it other than their personal opinions. I have a dozen or so B.Science sites I select that backs up my opinion or statement, rather than just a general link. You caught me this time, I'll try to do better for you....lol.

"A foil faced foam would be best with a higher R value than the Dow, plus you won't need a vapor barrier over it." ------ Does that create any problems below grade? 
From the last link above on pp. 13: "The fastest and most cost effective way to
provide insulation is covering the upper half
of the foundation wall with foil-faced
polyisocyanurate foam sheathing that is fire
rated for exposed use (*Figure 11*). This will
eliminate the greatest source of heat transfer
through the foundation wall while still
allowing the lower half of the wall to dry to the
interior. The joints between pieces of foam
sheathing must sealed using foil tape to
prevent air leakage that could result in
condensation on the cold foundation wall.
If at a later date the wall is to be finished,
expanded polystyrene (EPS) can be used to
cover the lower half of the wall (*Figure 12*).
Expanded polystyrene is semi-permeable to
water vapor and will allow the lower portion
of the wall to continue to dry inwards.
However, the expanded polystyrene will
require thermal protection with 0.5 inch of
gypsum board or equivalent." 



Gary


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## MJW (Feb 7, 2006)

It seems I already posted that exact thing with the Thermax in much fewer words. I doubt most people are going to read a 25 page blog to finish their basement.

Yes, that is concrete (poured walls) not cement. Correction accepted. Concrete is formed using cement if you want to be picky. 

Don't let the soap box get slippery.


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## ccarlisle (Jul 2, 2008)

Most houses I come across up here have full basements, and this is just another one... a full basement is intended eventually to be converted from 'bare' like the OP has, to liveable, which needs further work.

House builders have the choice of finishing it for you, or not. But by code they must provide a minimum of insulation where there is the most heat loss and that's what the OP's builder did.

I'll say it again, all that has to come off in order to insulate the concrete wall in order to 'live' down there. Polyisocyanurate panels with ot without foil, is one possibility - but every choice must be seen as integral part of a whole-house comfort system. 

As plentiful as Gary's links are, and before commenting on methods that relate to our climate up here, some of you should read the information. A lot of it was probably written by a Canadian anyway.


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## MJW (Feb 7, 2006)

ccarlisle said:


> Most houses I come across up here have full basements, and this is just another one... a full basement is intended eventually to be converted from 'bare' like the OP has, to liveable, which needs further work.
> 
> House builders have the choice of finishing it for you, or not. But by code they must provide a minimum of insulation where there is the most heat loss and that's what the OP's builder did.
> 
> ...


I still think you don't understand what a split level house is. It still has a liveable basement and it's still a full basement in most cases.

As far as Canadiens writing the laws, I wish they would keep them up there. We adopted many of them and created a huge mess and MANY ammendments to make them all work. The IRC code has been here in many forms since 2000 (maybe earlier) and since then, many problems. They are just finally coming around with ammendments to fix the code. Thanks for the incredible hockey players though. :thumbsup:

It was a simple question, that needed a simple answer, which some people gave. I had an assumption and then had to explain myself off topic. Sorry to the OP for the sway off topic.


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## Wildie (Jul 23, 2008)

Johnny Ren said:


> Hi, you guys are correct. The behind of the fiberglass is also concrete, so the total height is 8'. From what I understand from your discussion, I better to remove all existing stuff. then put foam board, then studs. It's really not what want. But if it's best solution, ....


 My son bought a new home (in Canada)last year. It has 9' concrete walls. The walls were insulated by two courses of what is foundation wrap. Same as in the pics.
It was passed by the building inspector, so I assume that it meets our minimum code.


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