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Basement Insulation - What is the Best Method?
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lostmandan



Joined: 09 Jul 2008
Posts: 146
Location: Kitchener/Waterloo, Ontario, Canada


PostLink    Posted: Tue Jun 30, 2009 4:54 am    Post subject: Basement Insulation - What is the Best Method? Reply with quote


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I am getting an electrical service upgrade/panel replacement done on Friday and I've opened up the wall around the panel to make space.

The walls in the basement are framed with 2"x2" and 1 1/2" white styrofoam insulation. The 2x2 top plate is secured to the member on top of the poured foundation and the 2x2 bottom plate is either resting on the concrete floor or fastened. I haven't determined this yet.

I have plans on how I want to frame in the electrical panel area, but I am not sure what the proper method of insulation is. At the moment the basement is about 14-15 degrees Celcius during the winter and it really doesn't vary much. I would really like to make it a bit warmer. I can see that the existing insulation is not sealed along the 2x2 framing and there are large gaps in places. It certainly could be done better.

That leads me to the point of this forum post .. looking for advice as I always am Smile

I think my options are as follows, but I really don't know which method is the 'right' one.

A) Finish the area with the same method - 2x2's, white styrofoam insulation, and wood paneling.

B) Finish the area with 2x2's but use the Dow Corning pink rigid foam (R7.5 for 1.5" thickness). I would probably take all of the paneling on two sides of the room off (against foundation - approximately 42') and fit the same pink rigid insulation in each cavity. I assume the correct method would be to caulk around the sides to seal against the 2x2's??

C) Pull all of the 2x2 framing, install 1.5" rigid pink insulation against foundation - R7.5 (insulation has overlapping edges, caulk the seams for a good seal), build a upper plate along the joists and frame the wall with 2x2's against the rigid insulation, cover with wood paneling.

I don't want to frame with 2x4" lumber because the room is about 11' wide and I would like to keep the extra 2".

I think drywall is out of the scope for now. I've been successfully removing 2x2 and paneling without damage so they could be reused without a problem so I think that I would do that to keep the renovation budget down.

Finally, what sort of treatment is needed against the inside of the foundation if the rigid pink foam is used? I would like to avoid moisture problems in the future. So far the basement has been pretty reasonable that way. I notice there are a few water drip marks down the wall under the areas I uncovered, but nothing terrible.

I am open to advice and any stories/experiences that you may have had.

I've attached a few photos of the area around the panel showing the opened wall, existing insulation, and 2x2 framing.

Cheers,
Dan



IMG_3343sm.jpg
 Description:
View of top 'plate' - note it is not attached to joist, but to wood member on top of foundation. I assume that Option C (above) would require securing a plate to the bottom of the joists to secure the wall framing.
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IMG_3343sm.jpg



IMG_3340sm.jpg
 Description:
Different view, 2x2s are against the foundation (for the most part). Wall is somewhat uneven so there are gaps.
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IMG_3340sm.jpg



IMG_3338sm.jpg
 Description:
Basement wall - white styrofoam insulation (original), 2x2 framing. Some HT components around waiting for me to get my a$$ in gear and have the room set up
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IMG_3338sm.jpg


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Nashou66



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PostLink    Posted: Tue Jun 30, 2009 1:07 pm    Post subject: Reply with quote

Id go with 2x4's, one reason it will give better sound by being able to add the fiberglass sound grade insulation.

Athanasios

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akajester



Joined: 09 Jul 2008
Posts: 933
Location: Wisconsin


PostLink    Posted: Tue Jun 30, 2009 1:37 pm    Post subject: Reply with quote

When I was finishing my basement, I talked to the framer about insulation. He said never put insulated boards against the cement wall in a basement. He said it traps water and causes mold to form. He said go with the standard insulated batting and then panel or drywall over it. He said that will allow the walls to "breathe". I skipped the wall insulation and just did the ceiling to help prevent sound transfer from the basement to the upper floor. that worked very well. I'm also using a dehumidifier to help keep things dry.

I also added in an air vent and return on opposite walls to help circulate the air.

I'm in wisconsin btw.
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ecrabb



Joined: 13 Mar 2006
Posts: 14569
Location: Utah

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PostLink    Posted: Tue Jun 30, 2009 4:15 pm    Post subject: Reply with quote

Nashou66 wrote:
Id go with 2x4's, one reason it will give better sound by being able to add the fiberglass sound grade insulation.

Athanasios, reframing the basement walls with batt insulation would provide some value in terms of relatively narrow-band sound isolation between adjoining spaces, but would offer extremely little or no benefit with respect to the sound in the actual room.

akajester wrote:
When I was finishing my basement, I talked to the framer about insulation. He said never put insulated boards against the cement wall in a basement. He said it traps water and causes mold to form. He said go with the standard insulated batting and then panel or drywall over it. He said that will allow the walls to "breathe".

That would be true if you used faced insulation, but there's still a problem... This is actually a pretty deep subject and a lot of people (even builders) don't understand it. But, I'll tell you what I learned before I started building my basement.

In a heating climate, in winter, you have a very warm interior and cold exterior walls... Well, the second law of thermodynamics basically says the warm, humid (relatively speaking) heated interior air is going to migrate toward the cold exterior. As it find its way through the plethora of penetrations, it migrates through the batt insulation and warm humid interior air finally condenses on the nearly ice-cold foundation wall. No problem, your walls "breathe", right?

The problem there is that for water to evaporate, it requires energy... Energy in the form of heat. If you've insulated with the batt insulation well, there won't BE any heat to vaporize the water. Not until spring, anyway. But, guess what? Just as things might be starting to dry into the interior (assuming you have low relative humidity in the basement), now you have the cooling season to contend with! You have the warm humid air permeating the foundation, and that air is now driving INTO the basement wall assembly because you have cold air (relative to the outside) in the interior! Basically, it will take forever to dry if it takes on moisture.

It sounds like a lose-lose, but there is a way. If you insulate a basement foundation first with unfaced 1.5" unfaced XPS (extruded polystyrene), that creates an R-7.5 or R-8 layer between the interior air and foundation. That insulating layer will prevent the warm interior air from condensing on the foundation in winter. It is a highly moisture resistant material (i.e. it doesn't hold moisture), but it is semi-permeable allow for drying. Combine that with typical R-13 unfaced batt insulation in a stud wall with no interior vapor barrier, and you'll end up with about a R-20 assembly that should stay dry and be able to dry to the interior if it does get wet.

I can dig up some documents on the subject if anybody's interested.

In the OP's case, if he doesn't have the room or inclination to build new 2x4 walls for batts, I'd just recommend switching from the white expanded polystyrene (EPS) insulation to 1.5" unfaced extruded polystyrene (XPS). It'll get you a couple points better R-value in the same space.

Sorry for the long post.

SC
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jask



Joined: 17 Mar 2006
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PostLink    Posted: Tue Jun 30, 2009 5:35 pm    Post subject: Reply with quote

do a web search for InSoFast panels, they might be just what you need. Fine homebuilding did an article a while back on how to do basement walls the right way- worth looking for just to better understand why you need the airflow and vapour barrier.
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Tom.W



Joined: 09 Mar 2006
Posts: 6557



PostLink    Posted: Tue Jun 30, 2009 7:32 pm    Post subject: Reply with quote

http://www.taunton.com/finehomebuilding/tools/departments/tools-and-materials/insofast-better-basement-insulation.aspx?nterms=61678
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lostmandan



Joined: 09 Jul 2008
Posts: 146
Location: Kitchener/Waterloo, Ontario, Canada


PostLink    Posted: Tue Jun 30, 2009 11:56 pm    Post subject: Reply with quote

akajester wrote:
He said never put insulated boards against the cement wall in a basement. He said it traps water and causes mold to form.


I've heard (and read) this too. I wonder why companies like Owen Corning recommend doing exactly that with their CelLok products. It is certainly enticing because it looks pretty straightforward - extruded foam panels, metal strips, drywall.


akajester wrote:
He said go with the standard insulated batting and then panel or drywall over it. He said that will allow the walls to "breathe". I skipped the wall insulation and just did the ceiling to help prevent sound transfer from the basement to the upper floor.


Just so I understand - you didn't insulate the walls at all? Just 2x4 framing and then drywall?

Vapour barrier? (or vapour retarder?)

I've heard lots of contradictory advice about sealing the concrete on the inside, vapour barrier on cold side or warm side, both sides, etc. I am really not sure what is best for a Southern Ontario climate at this point Razz
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lostmandan



Joined: 09 Jul 2008
Posts: 146
Location: Kitchener/Waterloo, Ontario, Canada


PostLink    Posted: Wed Jul 01, 2009 12:06 am    Post subject: Reply with quote

ecrabb wrote:
That would be true if you used faced insulation, but there's still a problem... This is actually a pretty deep subject and a lot of people (even builders) don't understand it.


I am noticing this as well - especially that there is no precise answer or all-round understanding with a number of folks I've talked to.

ecrabb wrote:
It is a highly moisture resistant material (i.e. it doesn't hold moisture), but it is semi-permeable allow for drying. Combine that with typical R-13 unfaced batt insulation in a stud wall with no interior vapor barrier, and you'll end up with about a R-20 assembly that should stay dry and be able to dry to the interior if it does get wet.


You mention no vapour barrier - I've been reading that some people recommend a vapour barrier that is laid under the bottom plate and then come up on either side of the batt insulation a few feet - apparently to avoid getting the batts wet if there are a few inches of water in the basement. I think that idea makes sense, but it wouldn't allow the assembly to dry if water managed to get in from the top.

Any thoughts on keeping things dry if there is an inch of water in the basement or is that type of situation something that is not worth designing around?

ecrabb wrote:
I can dig up some documents on the subject if anybody's interested.


I would appreciate it if you could Smile

ecrabb wrote:
In the OP's case, if he doesn't have the room or inclination to build new 2x4 walls for batts, I'd just recommend switching from the white expanded polystyrene (EPS) insulation to 1.5" unfaced extruded polystyrene (XPS). It'll get you a couple points better R-value in the same space.


I've been considering this as well. I would consider using some sort of caulk around all four sides of the XPS to seal it against the 2x2 members. I think that it would make sense at least.

As much as I would like to keep the 2x2, I may end up re-framing with 2x3 or 2x4. It would make electrical boxes easier to build into the wall (currently they jut out about 1 1/4" - ugly!) and would allow me to run some conduit for wiring.

ecrabb wrote:
Sorry for the long post.


Don't be - I like in depth posts. The more information, the better! Smile
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lostmandan



Joined: 09 Jul 2008
Posts: 146
Location: Kitchener/Waterloo, Ontario, Canada


PostLink    Posted: Wed Jul 01, 2009 12:12 am    Post subject: Reply with quote

jask wrote:
do a web search for InSoFast panels, they might be just what you need. Fine homebuilding did an article a while back on how to do basement walls the right way- worth looking for just to better understand why you need the airflow and vapour barrier.


I took a look at InSoFast panels - that is an interesting idea. If installing XPS directly against concrete is a bad idea (per the post above), would this be any different? I notice they have channels built into the back-side that apparently allow water to run down.. although I certainly hope no water would need to flow down the inside of the wall.
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lostmandan



Joined: 09 Jul 2008
Posts: 146
Location: Kitchener/Waterloo, Ontario, Canada


PostLink    Posted: Wed Jul 01, 2009 12:15 am    Post subject: Reply with quote

I made a quick call to a place that does spray foam insulation because it has been recommended as a good solution. I see that it is about $3/square foot to apply 3" thick layer. This is supposed to achieve R20 though and is apparently a good way of avoiding dry-out problems if things get wet.

Any experience with this type of insulation?
From what I've been reading it seems difficult to get R20 from batt insulation in a 2x3 wall.
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dturco



Joined: 06 Feb 2009
Posts: 3779
Location: Eastern Shore Maryland

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PostLink    Posted: Wed Jul 01, 2009 12:35 am    Post subject: Reply with quote

You'll never get R-20 with batt insulation in a 2x3 wall. R-19 requires a 2x6 wall cavity with straight batt insulation. I haven't used spray type insulation. Sorry I can't guide you on that. The rigid foam board at 2" is good for R-15 as Ecrabb said earlier which is better than the R-11 you'd get with batt insulation in the same space of the 2X3's.

Good luck making an Informed decision. I avoid this stuff like the plague and only use what I know, batt insulation or rigid foam board. The premium package insulation that I do use is rigid foam board with silver foil reflective surface in the crawl space, reflective side in towards the crawl space to bounce heat back under the home, with R-30 in the floor joist cavities.

It's not much help but there it is.

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Curt Palme
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PostLink    Posted: Wed Jul 01, 2009 1:56 am    Post subject: Reply with quote

Whatever you do, don't do it like the Olympic village is currently under construction downtown:

http://www.theprovince.com/Business/Village+could+mould+gold/1741033/story.html

What a clusterf**k!
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WanMan



Joined: 19 Mar 2006
Posts: 9668



PostLink    Posted: Wed Jul 01, 2009 4:31 am    Post subject: Reply with quote

Tom.W wrote:
http://www.taunton.com/finehomebuilding/tools/departments/tools-and-materials/insofast-better-basement-insulation.aspx?nterms=61678
While the good folks at FHB publishing may have their opinion, they've changed it over time. And if you talk to folks in their forums there are competing schools of thought. The biggest thing thing that has changed is the move away from a vapor barrier use and allowing the wall to breath.

Personally, I used Miraflex for insulation. This product was easier on the hands to work with and allows moisture to not be prevented from passing through the sheet rock. Of course, it really depends on how much moisture you have in the first place, and where it is coming from and traveling to.

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lovebohn



Joined: 16 Mar 2006
Posts: 178
Location: Wisconsin


PostLink    Posted: Mon Nov 09, 2009 9:39 pm    Post subject: Reply with quote

lostmandan wrote:
I made a quick call to a place that does spray foam insulation because it has been recommended as a good solution. I see that it is about $3/square foot to apply 3" thick layer. This is supposed to achieve R20 though and is apparently a good way of avoiding dry-out problems if things get wet.

Any experience with this type of insulation?
From what I've been reading it seems difficult to get R20 from batt insulation in a 2x3 wall.


I like the spray foam, but the cost is high. I think if we used it in our new home for all outside walls it was more than double the blow in cellulose cost. I still used it in the box sills since it installed a lot faster. I do have to agree I don't know the right or wrong way for doing basement walls and what will happen with the moisture. You also have to think about the concrete curing over the first few years and if that will retain or capture any moisture. I like the theory of poly on the outside walls.
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AnalogRocks
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PostLink    Posted: Tue Nov 10, 2009 2:14 am    Post subject: Reply with quote

lostmandan wrote:

Vapour barrier? (or vapour retarder?)
vapour barrier on cold side or warm side, both sides, etc. I am really not sure what is best for a Southern Ontario climate at this point Razz


The Vapour barrier always goes on the warm side.

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WanMan



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PostLink    Posted: Tue Nov 10, 2009 12:06 pm    Post subject: Reply with quote

If you use spray-on foam all over, and or use a vapor barrier then you will want to address the moisture you and your friends and family will introduce into the basement living space. You may not realize what that amounts to, but make sure you address it, or mold will adress you.
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akajester



Joined: 09 Jul 2008
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PostLink    Posted: Tue Nov 10, 2009 1:10 pm    Post subject: Reply with quote

lostmandan wrote:

akajester wrote:
He said go with the standard insulated batting and then panel or drywall over it. He said that will allow the walls to "breathe". I skipped the wall insulation and just did the ceiling to help prevent sound transfer from the basement to the upper floor.


Just so I understand - you didn't insulate the walls at all? Just 2x4 framing and then drywall?

Vapour barrier? (or vapour retarder?)

I've heard lots of contradictory advice about sealing the concrete on the inside, vapour barrier on cold side or warm side, both sides, etc. I am really not sure what is best for a Southern Ontario climate at this point Razz


That is correct, 2x4's against the cement and drywall over that. I skipped any insulation because I didn't feel the return on investment would be significant enough. heck, it's a basement, it'll always feel a little cooler than the upstairs. I doubt any insulation will fix that.

The framer I talked to has done alot of work in wisconsin for many years. He said you want the walls to breathe as much as possible. Otherwise you'll end up trapping water and mold will form. He said a good dehumidifier in the basement will work better than anything else. You also want to have some airflow, at least a return air vent if not a supply vent. If I had done insulation it would've been for acoustic reasons mostly.
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lostmandan



Joined: 09 Jul 2008
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Location: Kitchener/Waterloo, Ontario, Canada


PostLink    Posted: Tue Nov 10, 2009 3:42 pm    Post subject: Reply with quote

I agree that running a dehumidifier must help a lot. I have one in the basement and it keeps the relative humidity around 50%. During the warm summer months I dump a bucket a day out of the unit, but around this time of year it takes about 3-4 days to fill. During the dead of winter it doesn't pull a thing for weeks.

I think that I will be doing 2x4 framing with pink insulation batting - vapour barrier then drywall over the assembly. It seems like it is supposed to be the "correct" way to do it, although I still see photos and people talking about mold problems with that setup. I am not clear if those folks had pre-existing moisture issues or if the assembly caused the issues.

If I had more than 11'2" room width, I would install a layer of XPS between the concrete wall and the 2x4 framing. I don't want to lose the extra 1.5" though - the room is narrow already. It would look pretty odd at 10'7" and 30' long Wink

I have not seen signs of moisture seeping in, although there are a few 'drip marks' down the inside of the foundation wall (condensation I assume, although not many for the wall existing for 40 years). The research I have done tells me that proper insulation and vapour barrier will eliminate this condensation - a good thing.

I may work up the plan and post it here soon - we'll see how much time I have Smile This project has been swimming around in my head for months already.. I think it is high time to *do* something about it Smile

-- Dan
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ralpharch



Joined: 02 Nov 2007
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Location: Rockville, MD


PostLink    Posted: Mon Nov 16, 2009 4:51 pm    Post subject: Reply with quote

I have been thinking about relocating my theater room to the basement from a large upstairs bedroom.

Due to some existing mold problems my look into the situation of fixing it (leaks were from an AC condensate drain that cracked, some past water pipe (plastic) breaks by my neighbors and my water supplies, and back in the beginnine (1985 construction) some grading issues)

Bottom line is that my research indicates the correct solution is excavation down below the frost line on the exterior / grout/seal the trench at that level, and install exterior foam insulation against the poured concrete foundation. And no interior insulation.

That is what I was informed is the correct solution (actually insulating the entire basement vertical height is the real way to go but this approach gets you over 1/2 of the insulation savings and is doable versus trenching the entire foundation
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AnalogRocks
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PostLink    Posted: Mon Nov 16, 2009 5:00 pm    Post subject: Reply with quote

Wouldn't you also add weeping tiles at the same time you do your exterior insulation?
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