Best insulation method for outside walls? - Page 2 - AVS Forum
View Poll Results: Insulation method you prefer?
Foamboard, air gap, pink fiberglass 13 68.42%
Air gap, pink fiberglass 1 5.26%
Some other solution 5 26.32%
Multiple Choice Poll. Voters: 19. You may not vote on this poll

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post #31 of 46 Old 07-19-2013, 10:42 AM - Thread Starter
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Quote:
Originally Posted by kromkamp View Post

Once again I 100% agree. With this insulation methodology you do not have a vapor barrier to the inside of the wall - the foam is your vapor barrier. If you had enough batt insulation in place (like 12" or something extreme) this could be problematic, but with standard 2x4 batts you are fine. BSC has done very robust simulations for this methodology to show the average moisture movement and dew point inside the wall over a typical 12 month cycle.

The stud wall must not touch the spray foam, but the batts can be pushed right up against the spray foam. This is desirable to minimize air movement behind the stud walls.

Thanks for all the advice guys.

Can you remind me what BSC stands for? It's familiar to me, but I can't remember!

Sounds like 2" spray foam and R13 in a framed wall is best approach (once you get beyond all the other methods).

It sounds like my original approach of 3/4" XPS would be insufficient too (probably much like 1" spray) , if I want to have an *effective* barrier.
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post #32 of 46 Old 07-23-2013, 11:26 AM - Thread Starter
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I'm going to get prices for the 2" spray foam. I think that all things considered, there isn't enough reason to do something else. Perhaps 2" XPS MIGHT be cheaper, but it's certainly not quick and easy, and 2" doesn't end up cheap either.

Might cost a few dollars for spray foam, but long term, I'm sure it'll be worth it.

Unfortunately, I'll have to see how soon that happens, since it's a new build. Might need to wait a few months to get the basement totally dried out (the usual higher humidity in a new build..), and get finances all settled down.

Thanks for everybody's help! I've certainly learned a lot.
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post #33 of 46 Old 01-05-2014, 11:17 PM
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Late to the thread, sorry

We received a quote to use 2 lb, closed cell spray foam, 3 inches in all joist cavities and along the sides, parallel to the joists. This provides R21 (r7 per inch)

For our 1600 square feet basement remodel the quote was $900.

We are using 1.5 inch Dow Corning Foamular 150 glued on the slab with appropriate taping.

With this combination of insulation my wife is very pleased with the result. We are now thinking about using the open cell foam in the ceiling.

We plan on adding Superseal (without OSB) to the floors anf feel this will provide a very warm and comfortable basement.

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post #34 of 46 Old 01-06-2014, 05:45 AM
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I'm a builder in Michigan and endorse the 2" XPS foam and fiberglass approach. Be sure you seal all the edges of the foam. Use foam in a can and foam board adhesive on all joints to be sure you have 100% sealed joints. Also across the floor and adjoining walls. Tape ALL joints with tuck tape (stuff used for exterior building paper is fine). Michigan requires 1.5" min XPS foam thickness due to the dew point and condensation issues, need to have enough insulation to prevent it.
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post #35 of 46 Old 01-06-2014, 04:42 PM - Thread Starter
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I'm glad to see the new posts! I'm planning on getting a couple quotes on spray foam shortly - now that I have some funds.

I think what really kills my interest in XPS is trying to get a good seal with my foundation walls. They're that textured faux brickwork - that's far from a flat surface.
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post #36 of 46 Old 01-06-2014, 06:47 PM
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Quote:
Originally Posted by homeav View Post

I'm glad to see the new posts! I'm planning on getting a couple quotes on spray foam shortly - now that I have some funds.

I think what really kills my interest in XPS is trying to get a good seal with my foundation walls. They're that textured faux brickwork - that's far from a flat surface.

We ran into a similar issue with gluing the Foamular to the concrete walls. Unfortunately, we didn't have smooth concrete walls, there were large chunks of concrete that we needed to break off with chisel and hammer.

Lots of work and the chips of concrete went flying.

Look into some mechanical devices to help with keeping the xps on the wall.



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post #37 of 46 Old 01-06-2014, 06:56 PM - Thread Starter
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Quote:
Originally Posted by tsandtsand View Post

We ran into a similar issue with gluing the Foamular to the concrete walls. Unfortunately, we didn't have smooth concrete walls, there were large chunks of concrete that we needed to break off with chisel and hammer.

Lots of work and the chips of concrete went flying.

Look into some mechanical devices to help with keeping the xps on the wall.



I'll check it out. Thanks!

What reasons are there to use XPS instead of spray foam? Cost?

I know that spray isn't cheap, but 1.5-2" foam isn't cheap either..
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post #38 of 46 Old 01-06-2014, 07:07 PM - Thread Starter
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My wall surface..
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post #39 of 46 Old 01-06-2014, 07:22 PM
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I just tackled this same exact issue over the weekend. We have a storage room in our basement with a semi-exposed foundation outside due to our sloped yard which leads to a VERY cold and non-insulated room. I knew we had an issue every time my daughter had friends over and they looked little eskimos bundled up for sleepovers. I treated the foundation with two gallons of waterproof concrete sealer paint, then applied 1" foam board and taped all the seams and sprayed foam in the cracks, etc. Then I just framed it out (I have a little bit still to do), but I plan to apply insulation (hopefully tomorrow) in the stud cavities and put up a vapor barrier. I just glued the foam board to the foundation with an approved adhesive. Figure the new stud wall will hold it in place against the foundation adequately along with the adhesive. When I asked the helpful staff at the big box stores for plastic wall anchors (like in the video you show), they looked at me in total confusion. I could not find them in either store I checked. BTW- I can tell a noticeable difference already with just the steps completed so far even without the insulation batts installed. Good luck!!





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post #40 of 46 Old 01-06-2014, 08:18 PM
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Quote:
Originally Posted by homeav View Post

I'll check it out. Thanks!

What reasons are there to use XPS instead of spray foam? Cost?

I know that spray isn't cheap, but 1.5-2" foam isn't cheap either..

Yes, price however I would get pricing for the spray foam as the prices have come down. Building Science recommends either product.

We used 1.5 inch Foamular 150. 4 x 8 sheets. R-7.5.

I special purchased 2 pallets cheaper than the in stock 1.5 tongue and groove.

i have 20 sheets left that I am selling on craigs list.

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post #41 of 46 Old 01-15-2014, 10:16 AM - Thread Starter
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Well, I've had 1 contractor come out to give an estimate for spray foam. For closed cell, it's something like R6.3-6.5 per inch. I calculated around 900 SF of wall space. I asked for 2", and he practically gasped at that, being $3.75 PSF. He said that 1" was more practical (6.x R value, and then R13-R15 fiberglass in the wall cavity).

My walls have been absolutely dry with no sign of moisture since we moved in (poured, with outside drainage board, and a asphalt type sealant) , so I'm not concerned about water. So, I'm waiting to get the actual estimate later today. I'm probably going to get 2 more before I decide anything.

I think I'm going to price out some XPS in the meantime. I'm OK with spending a couple grand to insulate it properly, but the first estimator didn't really do anything to "sell" me on spray foam. I was kinda hoping for some kind of sales spiel.

I was trying to get some feel for the value of spray foam, and he said that he sees lots of block foundations that have cracks, moisture, etc.

I feel like a nutjob getting insulation quotes on a new build...
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post #42 of 46 Old 01-15-2014, 10:54 AM - Thread Starter
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$1 PSF for 2" XPS? This might be a no brainer. R value of 10 instead of 12-13, but I'm not concerned.

Owens Corning FOAMULAR 150 R10 2 in. x 48 in. x 8 ft. Scored Squared Edge Foam, $33.78 locally (32SF of 2").... plus $100 for adhesive? Yeah. $1-$1.20 PSF of 2'.

I think I was hoping that spray had come closer to the $1 PSF mark, at least for 1".
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post #43 of 46 Old 01-15-2014, 11:07 AM
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I'm pretty sure the xps is the vapor barrier. If you add another it might make for some issues.

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post #44 of 46 Old 01-15-2014, 12:37 PM - Thread Starter
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Originally Posted by ebpgh View Post

I'm pretty sure the xps is the vapor barrier. If you add another it might make for some issues.

I don't think that XPS is an issue, as long as you don't put 2 vapor barriers. It's even what I believe the my builder uses when finishing basements.
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post #45 of 46 Old 07-08-2014, 01:41 PM
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Quote:
Originally Posted by homeav View Post
Well, I've had 1 contractor come out to give an estimate for spray foam. For closed cell, it's something like R6.3-6.5 per inch. I calculated around 900 SF of wall space. I asked for 2", and he practically gasped at that, being $3.75 PSF. He said that 1" was more practical (6.x R value, and then R13-R15 fiberglass in the wall cavity).

My walls have been absolutely dry with no sign of moisture since we moved in (poured, with outside drainage board, and a asphalt type sealant) , so I'm not concerned about water. So, I'm waiting to get the actual estimate later today. I'm probably going to get 2 more before I decide anything.

I think I'm going to price out some XPS in the meantime. I'm OK with spending a couple grand to insulate it properly, but the first estimator didn't really do anything to "sell" me on spray foam. I was kinda hoping for some kind of sales spiel.

I was trying to get some feel for the value of spray foam, and he said that he sees lots of block foundations that have cracks, moisture, etc.

I feel like a nutjob getting insulation quotes on a new build...
@homeav -
What did u end up using?
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post #46 of 46 Old 07-22-2014, 12:23 PM - Thread Starter
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Originally Posted by kenchi View Post
@homeav -
What did u end up using?

Sorry for the delay.

I ended up doing 2" XPS on all walls.

In retrospect, I probably could have gotten away with a 1/2" air gap and then a normally framed 2x4 wall with R13 fiberglass.

So, I feel better with 2" XPS, but I have mixed feelings about the 4" of lost usable space -- since my walls might be dry enough without the 2" anyway.
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