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Discussion Starter · #1 ·
I am about 90% done with Drylok on the exterior walls in my space. I picked up a bunch of rigid foam today from HD. But I was reading the tube of adhesive and have a question:


The adhesive I am planning to use is PL-300, which is specifically for affixing rigid foam to substrate/concrete.

The tube of PL-300 says it is not recommended for attaching rigid foam to sealed concrete. However, the website doesn't say anything like that. Does anyone have any thoughts on this? Is there an alternative adhesive?
http://www.loctiteproducts.com/p/pl_...d-Adhesive.htm


Thanks for any input you have!


 

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I used the PL300 on my bare cinder block walls with no problems, however I did not Dry Lok before attaching them. I also used PL300 to attach foam board to my concrete basement floor without any problems. You will have to use an adhesive that is specifically made for foam board, other adhesives will "melt" the foam board. Keep in mind, if you frame your walls right next to the foam board, then it will hold the foam board in place.
 

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Discussion Starter · #3 ·
Hi bzbase - thanks for the info. Unfortunately, I need to keep a small airspace between the foam and the theater wall frame in order to preserve my sound-proofing efforts. Ted White told me that contact between the foam and wall framing will couple the two.


So - still on the hunt for the right product. I'm going through the Owens Corning website, but can't seem to find any info on the right adhesive. Maybe PL-300 will be okay...
 

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I used Henry 444 FRP Panel Adhesive applied with notched trowell. The on-line advertisements doesn't list rigid foam board but I just went down and read the container and it includes polystyrene foam insulation.
 

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Discussion Starter · #7 ·
Thanks for the link sirmebes - that document is interesting and has good info. I've been looking at something similar to that, here: http://www.buildingscience.com/docum...lation-systems .


I'm a little nervous about it because I have two non-porous surfaces that I'm trying to bond, but I bought some PL-300 today and am going to go for it tomorrow. I think I'll wait a few days before spraying Great Stuff around the perimeter in order to give the adhesive as much time to set/dry as possible.
 

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I used great stuff to adhere 2" extruded polystyrene to my unsealed walls. I was able to attach 4 8' boards with each can. If you have an issue with PL 300 on your sealed walls you could always try great stuff. I chose great stuff because it was easier and faster to work with.
 

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Discussion Starter · #9 ·
Thanks barlav - I bought some Great Stuff yesterday to use with the 2" XPS in the rim joists but I didn't know if it would be sticky enough to bond the full sheets of XPS to the substrate - based on your experience, it looks like it will work fine...thanks!
 

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I've been following this thread and am a little confused over all the concern about needing such a "comprehensive attachment" of the XPS to the wall. Since your panels will be setting vertically it seems there will be very little in terms of forces to make it fall away from the block wall (which you have already sealed with Drylock), so I find it hard to believe that the standard PL300 you originally intended on using won't provide enough adhesion to keep the sheet vertical and against the wall (which is the goal unless something else is at play).


Also, if you're framing your walls about 1' or so away from the XPS and using standard R-13 batts between those studs, the batts will most likely expand enough to contact the XPS which will also help hold it up.


Maybe there's some higher goal in mind here that I'm missing regarding the XPS to wall contact? Not trying to be controversial here, just trying to understand.
 

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Discussion Starter · #11 ·
Haha- fotto, you're entirely correct. The only higher goal I have here is satisfying my complete anal-ness and extreme paranoia of basement moisture!


My initial concern over the PL-300 was that I read somewhere on the interwebs (which I can no longer find) that using it between two non-porous surfaces meant that it would never dry. I remember reading it, and it was more of the 'comment on a blog' type than an authoritative source. The PL-300 tube also says "not recommended for use with sealed concrete", but the website doesn't say anything about that, so I have decided not to worry about it. http://www.loctiteproducts.com/p/pl_...d-Adhesive.htm . I think I'll just go with a little PL-300 plus some Great Stuff.


And you're also right that there won't be much in the way of force pulling the boards away from the wall - I dry fit one wall last night and it basically stood up on its own - so I could probably get away with just Scotch Tape if I wanted to
. I'm going to try to keep the theater framing and insulation from contacting the rigid foam in order to prevent any coupling (again, probably overly anal), but I'm sure PL-300 and Great Stuff will be more than adequate to keep the foam against the wall.


I'm going to use Tyvek tape to seal the joints between the foam boards. Next question (LOL): do I also need a little sealant/caulk for the tongue and groove joint between the boards, or is the tape enough?
 

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Well, you'll fit in perfectly fine here in the "anal zone" with the rest of us



Just my opinion, but I think that the tape is enough.
 

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Ben, you are cracking me up. No detail is too minute!



...and this is in the driest basement I've ever been in!
 

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Discussion Starter · #14 ·
Haha - glad you are having a good laugh Andreas!
But shouldn't you be off building your theater?? Don't you have a baby on the way or something??
I am hoping that a little extra attention in this phase will prevent me from a potential issue somewhere down the line... But if I were you, I'd be laughing at me too haha!
 

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I'm too busy going to baby showers and birthing classes to work on my theater!



You are doing good work! Just don't get too caught up into every detail.
 

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Discussion Starter · #17 ·
Thanks Ant - I think that's my plan exactly. And is this also a license to blame you if I run into any trouble???



And thanks for the compliment Andreas!
 

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The issue I have with not using applying adhesive to the full panel (with a notched trowel or something) is that depending how you squirt it on, you may leave air gaps behind the panel.


The goal of this process it to prevent any warm moist air from the room coming in contact with the concrete. Now other things like sealing seams with tape etc. will help prevent this as well but you want the foam and concrete to essentially be "as one" (as if the concrete were poured into the foam forms).


When I pulled foam off my dad's basement walls after a number of years I found that he just used a caulk gun to apply adhesive which left gaps behind the panels which did allow some moisture/mold.
 

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Quote:
Originally Posted by RPh Drew /forum/post/19532343


The issue I have with not using applying adhesive to the full panel (with a notched trowel or something) is that depending how you squirt it on, you may leave air gaps behind the panel.


The goal of this process it to prevent any warm moist air from the room coming in contact with the concrete. Now other things like sealing seams with tape etc. will help prevent this as well but you want the foam and concrete to essentially be "as one" (as if the concrete were poured into the foam forms).


When I pulled foam off my dad's basement walls after a number of years I found that he just used a caulk gun to apply adhesive which left gaps behind the panels which did allow some moisture/mold.

No matter how you apply the rigid foam there will most likely be air gaps but they shouldn't cause any problems. The extruded polystryrene is mold resistant so there really isn't anywhere for the mold to grow or attach to. Also, very few basement walls are perfectly true or straight so even if you trowel on adhesive you can't be guaranteed a uniform attachment. Also, the foam along with the tyvek tape will serve as a vapor barrier. As long as your foam sticks to the wall you will be fine air gaps or not. I had to remove one of my foam panels months after I used great stuff to attach it to the wall to get to a persistent crack that was leaking. I had to break the panel apart to get it off the wall. It was attached very well to the wall.
 

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Quote:
Originally Posted by barlav /forum/post/19532791


No matter how you apply the rigid foam there will most likely be air gaps but they shouldn't cause any problems. The extruded polystryrene is mold resistant so there really isn't anywhere for the mold to grow or attach to. Also, very few basement walls are perfectly true or straight so even if you trowel on adhesive you can't be guaranteed a uniform attachment. Also, the foam along with the tyvek tape will serve as a vapor barrier. As long as your foam sticks to the wall you will be fine air gaps or not. I had to remove one of my foam panels months after I used great stuff to attach it to the wall to get to a persistent crack that was leaking. I had to break the panel apart to get it off the wall. It was attached very well to the wall.

Some good points. I am just trying to differentiate between "adhesion" and "sealing". My dad's was stuck very well to the walls as well. I had to use a wide putty knife to scrape it off in pieces. There have, however, been some comments that seems to focus more on keeping the panels from falling off the walls which isn't really the issue.

Quote:
Originally Posted by barlav /forum/post/19532791


As long as your foam sticks to the wall you will be fine air gaps or not.

This I would disagree with. The OP references a diagram in his build thread of which he is trying to follow "very carefully"... anally...
and it goes into detail about sealants, adhesive, or gaskets which is the same article I referenced when constructing my own. The article that went with the diagram (which isn't posted in his thread) went into more detail.


Keeping consistent with that is where I recommend going a little further which is what I did as well.


At the end of the day there are a lot of professional opinions out there (which mine is obviously not, professional that is) about how to insulate a basement. I think most agree that at least one goal is to keep warm, moist air from coming in contact with the cool concrete wall where the moisture will condensate. There are a variety of lengths one can go to accomplish this and also an amount of duplication in the process.


[stepping on soap box] Lastly, I have typed many a response in the past about water issues as my previous home's basement flooded twice in two weeks. The OP sealed with drylock. Why? Are there any issues with water you are blocking or is it just duplicaiton as well. Hopefully, it is just duplication of an overall water plan which includes grade, gutters, and drain tile. I have seen far too many basement theaters in here damaged as a result the lack of an overall water plan. [stepping off soap box]
 
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