I have read through the other threads here that are on crawlspace insulation/encapsulation but I have more questions than what those covered. Background info first: My house was built in ’64. I live in western NYS and the winters are pretty bad. Summers can be humid. My crawlspace is roughly 4 ft high and about 270 sq ft. The foundation walls are untreated cinder/concrete blocks and the floor is concrete but it is not level by any means (has a slight downward slope). Looks like it was just dumped cement, perhaps somebody just had extra stuff to get rid of at the time of being built. The concrete job is nothing special and it is not a tight job by any means. Better than an all dirt floor but not usable for a real floor. I want to use the crawlspace as storage only. There is a smell of moisture that permeates in the basement (which is right next to the crawlspace) but I have not seen any signs of a wet basement. I believe this is just water vapor coming up through the crawlspace floor but once I apply a vapor barrier to it, this should go away. I currently have a couple small sheets of plastic taped up to the walls to see if there is any water coming in or too much humidity inside the space. I see no evidence of moisture coming in. I want to install rigid insulation but I do have some questions.
1) Before I do any insulation work, would it be worthwhile to put on a coat or two of drylock paint on the blocks? If it is not necessary, then I won’t but it may be something seen as an insurance policy to minimize future water events.
2) If using standard rigid foam, it needs to be covered by drywall. This brings up my next question about flame barriers: At what point does something need this? For instance, there is no direct flame in the crawlspace but the furnace does have its exhaust pipe that runs up through it. Technically there is no flame in the exhaust tube but this is where my knowledge is limited. Is this a case of having to use drywall or Thermax insulation instead?
3) What adhesive do you use to attach the rigid foam to the walls? Liquid nails or other? There are lots of tubes to choose from at the h/w store.
4) If I had to do drywall, this would require furring strips at least. This would imply drilling into the concrete blocks to attach them. How does doing something like this not compromise the foundation walls in terms that you just put a hole in the concrete and now water can get through easier? I realize that you are not drilling through the whole foundation wall and only do so for a couple inches with concrete fasteners but I just wanted to ask if any special needs have to be addressed when you do this? I suppose I could just glue the drywall up to the rigid foam. This seems a little cheesy in that you glue everything up. Perhaps it is legit but doesn’t hurt to ask about it.
5) I have the Bruce Harley book for Weatherizing, and if you have that book, page 47 shows that the 6mil vapor barrier is on the outside of the insulation that is up on the walls. Why would you not tuck the vapor barrier underneath the rigid foam (against the blocks directly) rather than on the surface of the rigid insulation? It would be a sandwich of sorts, with the layers going concrete blocks, vapor barrier and tape, and then rigid foam.
6) When I put rigid foam in at the rim joist area, in there any particular glue to use? I am planning on buying a foam spray gun since they are not that expensive so I will be able to get decent use out of a can of spray foam (not that Great Stuff brand though, more like Pur Fill).
7) There is a product called soy seal foam spray. Is it worthwhile or not? Saw it at HD the other day and was wondering if it good stuff or not.
Thanks for any help
dennis
Replies
Edited from the above post:
I have read through the other threads here that are on crawlspace insulation/encapsulation but I have more questions than what those covered.
Background info first: My house was built in '64. I live in western NYS and the winters are pretty bad. Summers can be humid.
My crawlspace is roughly 4 ft high and about 270 sq ft. The foundation walls are untreated cinder/concrete blocks and the floor is concrete but it is not level by any means (has a slight downward slope).
Looks like it was just dumped cement, perhaps somebody just had extra stuff to get rid of at the time of being built.
The concrete job is nothing special and it is not a tight job by any means. Better than an all dirt floor but not usable for a real floor.
I want to use the crawlspace as storage only. There is a smell of moisture that permeates in the basement (which is right next to the crawlspace) but I have not seen any signs of a wet basement.
I believe this is just water vapor coming up through the crawlspace floor but once I apply a vapor barrier to it, this should go away.
I currently have a couple small sheets of plastic taped up to the walls to see if there is any water coming in or too much humidity inside the space.
I see no evidence of moisture coming in. I want to install rigid insulation but I do have some questions.
1) Before I do any insulation work, would it be worthwhile to put on a coat or two of drylock paint on the blocks? If it is not necessary, then I won't but it may be something seen as an insurance policy to minimize future water events.
2) If using standard rigid foam, it needs to be covered by drywall. This brings up my next question about flame barriers: At what point does something need this?
For instance, there is no direct flame in the crawlspace but the furnace does have its exhaust pipe that runs up through it. Technically there is no flame in the exhaust tube but this is where my knowledge is limited. Is this a case of having to use drywall or Thermax insulation instead?
3) What adhesive do you use to attach the rigid foam to the walls? Liquid nails or other? There are lots of tubes to choose from at the h/w store.
4) If I had to do drywall, this would require furring strips at least. This would imply drilling into the concrete blocks to attach them.
How does doing something like this not compromise the foundation walls in terms that you just put a hole in the concrete and now water can get through easier?
I realize that you are not drilling through the whole foundation wall and only do so for a couple inches with concrete fasteners but I just wanted to ask if any special needs have to be addressed when you do this?
I suppose I could just glue the drywall up to the rigid foam. This seems a little cheesy in that you glue everything up. Perhaps it is legit but doesn't hurt to ask about it.
5) I have the Bruce Harley book for Weatherizing, and if you have that book, page 47 shows that the 6mil vapor barrier is on the outside of the insulation that is up on the walls.
Why would you not tuck the vapor barrier underneath the rigid foam (against the blocks directly) rather than on the surface of the rigid insulation? It would be a sandwich of sorts, with the layers going concrete blocks, vapor barrier and tape, and then rigid foam.
6) When I put rigid foam in at the rim joist area, in there any particular glue to use? I am planning on buying a foam spray gun since they are not that expensive so I will be able to get decent use out of a can of spray foam (not that Great Stuff brand though, more like Pur Fill).
7) There is a product called soy seal foam spray. Is it worthwhile or not? Saw it at HD the other day and was wondering if it good stuff or not.
Thanks for any help
dennis
Edited 8/2/2009 3:19 pm ET by rez
Let's run this thru again.
Bump
Greetings dennis,
As a first time poster Welcome to Breaktime.
This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.
Perhaps it will catch someone's attention that can help you with advice.
I took the liberty of breaking you post into smaller paragraphs to ease the readability.
Cheers
94969.19
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Can't answer everything, but as for attaching foam, you can buy tubes of "caulk" specifically for this, but since you mentioned getting a foam gun, you can use poly foam to cement the panels to the wall, propping them up with boards as until the faom cures
Is the crawl above or below grade ( or both)?
Thanks for the reply. Crawlspace is mainly below grade. Funny thing about this all is that I downloaded all of the related articles from the FHB website and I think I have most of my questions answered. It took a lot of digging to deduce what I needed to do. Also had to call the local code guy to verify some things. There are a couple ways to do the insulation, one being with the rigid foam stuff and the other being with insulation blankets rated for open exposure. Certainteed makes a product specifically for this. The polyisocyanurate rigid foam used in an exposed crawlspace is quite pricey and seems to be hard to get where I am at. Given that typical rigid foam board at HD or Lowes is around $15/sheet, the poly stuff is at least twice that. I will say that certainteed has a better website for insulating crawlspaces. Owens Corning was pretty useless for it. OC has products for it but I could not find anything useful on the site. It is almost as if they don't want a homeowner to know about what to use. The foam gun thing is a cool idea but I read a couple reviews on amazon.com about these guns and the reviewers stated that they are a pain to clean. They work pretty good but unless you are going to do a lot of area, it may not pay to buy them.