# Foam Board Question???



## Rooki (Nov 30, 2011)

I have been insulating the interior of my poured basement walls and rim joists on my way to finishing my basment. I am using 2 inch pink XPS sheets as recommended here. They are costing me about $27/sheet. 

My friend has a neighbor that is building a new home and has some left over 2 inch Dow Styrofoam board that the contractor was using. I can get this pretty cheap, but I am concerned that it is different than what I am currently using and I don't want to cause an issue. 

It is blue and say's Dow Styrofoam "utility fit" on it. When I searched it on line it claims it is XPS, but the boards do not say XPS on them like my current boards do.

I dont know where in the home the contractor was using the blue foam boards, but I am assuming that it was maybe around the foundation as the rest of the house has not progressed very far.

Would this board work for basement walls and rim joists? Is it the same as my current pink XPS sheets?


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## cleveman (Dec 17, 2011)

Go for it, Rooki.

No need to buy, however, just go in there after the workers have left at night.

Don't leave any tracks heading towards your house, however.


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## Trucon01 (Jan 10, 2012)

I was also going to use the blue Dow 2in foam Tongue and Groove. However, Home Depot only special orders this for 50.00+ per sheet. Not to mention I had to buy at least 192 or 196 sheets... So I found a store that had the 1 and 2 in Owens Corning pink foam. The 1x2x4 is $9.90 and the 2x2x4 is 16.64. I was going to double up the 1 in to make it 2 in, but stagger the seams...


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## user1007 (Sep 23, 2009)

Careful! Most foam board is not fire rated and you have to seal it with drywall.
Could void fire insurance or have claim denied.


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## moneymgmt (Apr 30, 2007)

Check craigslist. Generally somebody on there has some for sale depending on where you live. I found a roofing contractor who removed 200pcs of 3"x4'x8' from a commercial building and was selling them for $15 each. He was tired of people buying 3 here or 10 there, we worked out a deal on 50 pieces to do my rim joists and basement. Saved me at least $1500 so my wife can deal with them sitting in a pile in the basement until I can drylok it first :thumbsup:


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## AGWhitehouse (Jul 1, 2011)

moneymgmt said:


> Check craigslist. Generally somebody on there has some for sale depending on where you live. I found a roofing contractor who removed 200pcs of 3"x4'x8' from a commercial building and was selling them for $15 each. He was tired of people buying 3 here or 10 there, we worked out a deal on 50 pieces to do my rim joists and basement. Saved me at least $1500 so my wife can deal with them sitting in a pile in the basement until I can drylok it first :thumbsup:


3" of Polyiso or XPS will do exactly what drylok does. So save your ear drums from the wifes complaints, your arms from the paint roller, and your wallet from the store, and just put up the foam already. Just be sure to cover it with a thermal/ignition barrier per code.


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## moneymgmt (Apr 30, 2007)

AGWhitehouse said:


> 3" of Polyiso or XPS will do exactly what drylok does.


Can't agree with you here. I have yet to see foam board designed to penetrate the concrete to form a 15 year waterproof warranty like Drylok. If you do not seal the concrete first you are running the risk of a hidden leak down the road and having to tear down the foam to find out where it is. A few hundred dollars invested in Drylok is worth it to not have to rip down a few thousand dollars in foam board to locate a leak. Already got my first coat on!


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## jklingel (Dec 21, 2008)

As I noted on another thread yesterday, be very careful buying pulled foam from roofers. If it has been pulled for a reason (like it has been wet and gone through freeze/thaw cycles) it may be pretty useless. Apparently the cycles break up the foam and any moisture that gets near them will wick in, and freeze again, rendering the R value negligible. If the foam is good, why was it replaced?


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## AGWhitehouse (Jul 1, 2011)

moneymgmt said:


> Can't agree with you here. I have yet to see foam board designed to penetrate the concrete to form a 15 year waterproof warranty like Drylok. If you do not seal the concrete first you are running the risk of a hidden leak down the road and having to tear down the foam to find out where it is. A few hundred dollars invested in Drylok is worth it to not have to rip down a few thousand dollars in foam board to locate a leak. Already got my first coat on!


I will abstain from any further argument on the topic, but do you really think a coat of paint (yes drylok is paint) will stop a leak? Best of luck to you!


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## Windows on Wash (Aug 30, 2011)

AGWhitehouse said:


> I will abstain from any further argument on the topic, but do you really think a coat of paint (yes drylok is paint) will stop a leak? Best of luck to you!


+1

If you have a leak, all drylok will do is mask where it is originating in some cases.

XPS and EPS are far less susceptible to degradation if I recall correctly. Most XPS and EPS are skinned of some sort and therefore absorb little to no moisture.


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## Gary in WA (Mar 11, 2009)

Find “Waldo” (dryloc) on the concrete wall: 

1. locate vapor *barriers on the outside*-allow inward drying to the space 

2. right below photo 2: plastic (or dryloc)* v.b. prevents inward drying* 

3. right below photo 3; plastic *film prevents inward drying* 

4. 5th para. below fig. 9-allow foundations to *dry inwards*; be vapor *semi-im*permeable, vapor *semi-permeable*, or vapor *permeabl*e---- not vapor impermeable (dryloc) 

5. third point below fig.10--- rigid foam board is vapor semi-impermeable or semi-permeable (*no plastic facings* or foil) which would make them vapor impermeable (like dryloc)

http://www.buildingscience.com/documents/digests/bsd-103-understanding-basements?full_view=1

Gary


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## dodie1963 (Nov 20, 2014)

I want to add foam board over existing drywall in garage for added insulation. The interior rooms along the garage walls are cold.The walls have insulation in them so blowing insulation in is not an option/ I really don't wanna remove drywall. Does anyone have any suggestions


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## Windows on Wash (Aug 30, 2011)

I would start by making sure the garage wall is airtight.

Ideally any vapor control levels should be on the warm wall side.

Make sure the wall is airtight, use a rigid foam that is unfaced, and be sure to covered with drywall right away.


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## dodie1963 (Nov 20, 2014)

Which foam board would you recommend? WHat about foil faced board? The garage wasn't spackled so im working on that now. What harm will I do if I don't get the sheetrock up right away. Im planning on taping all the foam board joints with foil tape.


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## Windows on Wash (Aug 30, 2011)

Don't bother with foil faced if you aren't going to use it as a radiant barrier (i.e. air space).

Sheetrock needs to go over any exposed foam. Gotta be safe.


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## mikegp (Jul 17, 2011)

I would love to know how many people successfully filed a warranty claim with drylok or any other similar product. Every story I have ever heard just ends with them blaming it on the installation/application/prep work. Warranties aren't what they used to be.


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## ddsrph (Nov 23, 2013)

jklingel said:


> As I noted on another thread yesterday, be very careful buying pulled foam from roofers. If it has been pulled for a reason (like it has been wet and gone through freeze/thaw cycles) it may be pretty useless. Apparently the cycles break up the foam and any moisture that gets near them will wick in, and freeze again, rendering the R value negligible. If the foam is good, why was it replaced?


The polyiso foam is usually replaced when a commercial metal roof is replaced. 
It has nothing to do with the foam condition. I have a large quantity that I am using in a new house. It was purchased within days of comming off a large commercial roof and no sign of being wet or damaged.

JM


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## 1985gt (Jan 8, 2011)

jklingel said:


> As I noted on another thread yesterday, be very careful buying pulled foam from roofers. If it has been pulled for a reason (like it has been wet and gone through freeze/thaw cycles) it may be pretty useless. Apparently the cycles break up the foam and any moisture that gets near them will wick in, and freeze again, rendering the R value negligible. If the foam is good, why was it replaced?


Being careful when buying used Poly Iso is a good idea I will add a lot of the time the insulation is replaced because the new roof installation has a manufactures warranty, the manufacture will not cover the old insulation. They want new. Poly Iso is really easy to tell if it has been wet before. Also most insulations R value will decrease over time.



Windows on Wash said:


> XPS and EPS are far less susceptible to degradation if I recall correctly. Most XPS and EPS are skinned of some sort and therefore absorb little to no moisture.


EPS is like a sponge, it will absorb an incredible amount of moisture and hold it in, Iso is similar. XPS is better but still will absorb some moisture.



ddsrph said:


> The polyiso foam is usually replaced when a commercial metal roof is replaced.
> It has nothing to do with the foam condition. I have a large quantity that I am using in a new house. It was purchased within days of comming off a large commercial roof and no sign of being wet or damaged.
> 
> JM


Correct. We have a few 100 squares of 2.7" Iso we pulled off a ballast roof this summer. The wet went in the trash the good 4x8 sheets went on the trailer.


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## Windows on Wash (Aug 30, 2011)

1985gt said:


> EPS is like a sponge, it will absorb an incredible amount of moisture and hold it in, Iso is similar. XPS is better but still will absorb some moisture


Agreed.

I was referring (gotta rack my brain as that was 2012) to the poly-faced EPS.

Regardless, you have to have properly water sealing and management on the exterior of the foam/wall combo.


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## 1985gt (Jan 8, 2011)

Windows on Wash said:


> Agreed.
> 
> I was referring (gotta rack my brain as that was 2012) to the poly-faced EPS.
> 
> Regardless, you have to have properly water sealing and management on the exterior of the foam/wall combo.


We mostly see regular white EPS, I've had 3" 4x8' weigh had to be well over 400 lbs. Amazing how much a concrete deck will let the water sit there.

They have so many new ridged board insulations it's not easy to keep track of everything. 

To me EPS = white popcorn.
XPS = Blue/pink/ probably every other color. 10X as stiff as EPS.

Iso is Iso.

Of course they all can have aluminum facer and a host of other stuff.


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## ddsrph (Nov 23, 2013)

The house science article I used for my planned insulation used XPS against the block and the polyiso over the XPS. I plan to do the same. The key to success has to be a dry block wall for either to work. 

JM


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## tekart (Dec 6, 2014)

The only reason to use foil faced board is if you have an air gap between the foil and the interior or exterior surface. The foil is designed to reflect heat and if it is hard up against the inside surface of drywall, or the inside surface of your poured concrete basement wall, it will not serve any function. If you can set the foil backed phone a half inch away from your drywall then it will serve as a functioning reflector for the interior heat and reflected back into the building. In all other cases where the foam is in contact with building materials, just use the plane foam.



dodie1963 said:


> Which foam board would you recommend? WHat about foil faced board? The garage wasn't spackled so im working on that now. What harm will I do if I don't get the sheetrock up right away. Im planning on taping all the foam board joints with foil tape.


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## ddsrph (Nov 23, 2013)

On my basement house I have decided to go with one inch blue XPS against block, two and one half inch recycled polyiso, then one half inch blue board on top for a total of four inches. All of this will be held tight by placing the studs flat side against foam leaving a 1 1/2 space that will also be filed by cut poly ISO to fill the spaces. I plan to overlap all joints nearly two feet and to use calk to seal edges. I have just done a test of the liquid nails "foam board caulk" and found it to work well. I glued a three inch square of XPS to block and iit stuck immediately and after it set was difficult to remove.

JM


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