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Posted: Nov 10, 2007 05:09 PM	Foam and Batts I have a new rancher with 2x8 walls i live in Pa. I am having closed cell foam sprayed 3 inches in wall to meet R-19 code, and then have approx. 3 inches left. I was told to not leave it open behind drywall, rather install an unfaced batt to help with sound and extra R value. I was told not to have paper on batts because 2 vapor barriers is not good. If i install 4 inches of batt in my wall, will I get condensation problems, because of wall thickness, or should I just leave 3 inch wall space behind drywall open till foam starts? I hear both sides, and suggestions. Note, I have alot of R 30 around because I was going to Batt my house originally, but decided to pay the extra amount and go all out with foam.
Rob Granger Posted: Nov 10, 2007 07:34 PM	Derek, If you leave the additional space open within the stud cavity any excess moisture in the house(moisture levels fluctuate) will migrate into the stud cavity but when the house dries out so will the cavity. You will not have condensation because you have moved the condensation point with the installation of the foam. An air space within the cavity actually improves your R-value within. If you add fiberglass to the cavity you will not have condensation but more R-value which with three inches of foam I believe you have enough insulation. YES FOAM Rob
Posted: Nov 10, 2007 09:12 PM	So ur saying that I can add fiberglass, but really don't have to, correct? Is it really worth it? I have a lot of r30 because of old plans, i was gonna use it up, will I ever have a problem with it in the space w/o the paper on it. I'm going for max, and I have it so hmmmmmm.....
Gerry Wagoner Posted: Nov 10, 2007 11:06 PM	Hi Derek. You will love your foamed house. As to the left over cavity in the 2x8 walls, you can leave it open or install filler insulation in there. Either way is fine. The dead air space is worth a couple R-value, and cellulose or filterglass won't hurt anything. Cellulose will definitely improve the STC rating of the wall (sound transmission class). Moisture? What moisture? There will be no observable vapor drive in or out of the wall assembly after it is foamed. Have fun, olger
Posted: Nov 10, 2007 11:26 PM	Thanx, If i do install batts, no paper right just unfaced since the foam is my barrier? Or should I use sound designed batts? That I can do myself?
SprayFoamSupply.com Posted: Nov 11, 2007 06:54 AM	That's right, NO paper! The foam is a vapor retarder and if you use the paper you will have filterglass sandwiched between 2 vapor retarders, a NO NO! George
Posted: Nov 11, 2007 11:17 PM	Thank You for all your input, I really do appreciate it!!!!!!!!!!!!
Edward Brassington Posted: Nov 18, 2007 08:45 PM	Why not just forget about the fiberglass, maybe donate it to a local habitat for humanity project or other non profit group. With three inches of foam your house will be extremely well insulated, comfortable and energy efficient. Did you know fiberglass is a known carcinogen, it is an over rated product. In reality it will not improve the energy efficiency of your home, the foam is doing that.
Gerry Wagoner Posted: Nov 19, 2007 06:43 PM	Correct, FM. oG
Posted: Dec 31, 2007 11:08 PM	What about covering my foam in my attic. I only have an access hatch of min size 22x30. I cannot store in my attic and probally can't cover foam with any kind of sheet material due to space limitations.(ductwork in attic, unvented) I was gonna put 1 1/2 of fiberglass over foam to meet ignition barrier. Which kinda sux cause I wanted to keep fiberglass out of the house completely. Is there somthing else that would be easier? And Yes, I love my foam house thanx!
quentin Posted: Jan 01, 2008 09:57 PM	If it is a tight space then you may want to use blown in cellulose for the ignition barrier since it is not going to cause the itching or the health issues I believe. Am I correct guys? BTW, I learned years ago doing my house with my dad when I was a kid that an old upright vacuum works great for a blower! LOL We just opened the bags, I fed the beaterbar and he had a hose taped to the output side instead of a bag. It fluffed it up nice and blew it out pretty well. That is if someone is wanting to do it themselves on the cheap for that type of insulation. A cheap old vacuum from Goodwill and it was done.
Tim O'Keefe Posted: Jan 01, 2008 10:03 PM	There are paints that can be applied on top of the foam which meet thermal barrier requirements. http://www.tpr2.com/afes-f1e.htm This is easy to apply in an attic where access is difficult. Tim Granite State Spray Foam Co.

Author

Comments

Posted: Nov 10, 2007 05:09 PM

Foam and Batts

I have a new rancher with 2x8 walls i live in Pa. I am having closed cell foam sprayed 3 inches in wall to meet R-19 code, and then have approx. 3 inches left. I was told to not leave it open behind drywall, rather install an unfaced batt to help with sound and extra R value. I was told not to have paper on batts because 2 vapor barriers is not good. If i install 4 inches of batt in my wall, will I get condensation problems, because of wall thickness, or should I just leave 3 inch wall space behind drywall open till foam starts? I hear both sides, and suggestions. Note, I have alot of R 30 around because I was going to Batt my house originally, but decided to pay the extra amount and go all out with foam.

Rob Granger

Posted: Nov 10, 2007 07:34 PM

Derek,
If you leave the additional space open within the stud cavity any excess moisture in the house(moisture levels fluctuate) will migrate into the stud cavity but when the house dries out so will the cavity. You will not have condensation because you have moved the condensation point with the installation of the foam. An air space within the cavity actually improves your R-value within. If you add fiberglass to the cavity you will not have condensation but more R-value which with three inches of foam I believe you have enough insulation.

YES FOAM
Rob

Posted: Nov 10, 2007 09:12 PM

So ur saying that I can add fiberglass, but really don't have to, correct? Is it really worth it?
I have a lot of r30 because of old plans, i was gonna use it up, will I ever have a problem with it in the space w/o the paper on it. I'm going for max, and I have it so hmmmmmm.....

Gerry Wagoner

Posted: Nov 10, 2007 11:06 PM

Hi Derek. You will love your foamed house.

As to the left over cavity in the 2x8 walls, you can leave it open or install filler insulation in there. Either way is fine.

The dead air space is worth a couple R-value, and cellulose or filterglass won't hurt anything. Cellulose will definitely improve the STC rating of the wall (sound transmission class).

Moisture? What moisture? There will be no observable vapor drive in or out of the wall assembly after it is foamed.

Have fun,

olger

Posted: Nov 10, 2007 11:26 PM

Thanx, If i do install batts, no paper right just unfaced since the foam is my barrier? Or should I use sound designed batts? That I can do myself?

SprayFoamSupply.com

Posted: Nov 11, 2007 06:54 AM

That's right, NO paper! The foam is a vapor retarder and if you use the paper you will have filterglass sandwiched between 2 vapor retarders, a NO NO!

George

Posted: Nov 11, 2007 11:17 PM

Thank You for all your input, I really do appreciate it!!!!!!!!!!!!

Edward Brassington

Posted: Nov 18, 2007 08:45 PM

Why not just forget about the fiberglass, maybe donate it to a local habitat for humanity project or other non profit group. With three inches of foam your house will be extremely well insulated, comfortable and energy efficient.

Did you know fiberglass is a known carcinogen, it is an over rated product. In reality it will not improve the energy efficiency of your home, the foam is doing that.

Gerry Wagoner

Posted: Nov 19, 2007 06:43 PM

Correct, FM.

oG

Posted: Dec 31, 2007 11:08 PM

What about covering my foam in my attic. I only have an access hatch of min size 22x30. I cannot store in my attic and probally can't cover foam with any kind of sheet material due to space limitations.(ductwork in attic, unvented) I was gonna put 1 1/2 of fiberglass over foam to meet ignition barrier. Which kinda sux cause I wanted to keep fiberglass out of the house completely. Is there somthing else that would be easier?

And Yes, I love my foam house thanx!

quentin

Posted: Jan 01, 2008 09:57 PM

If it is a tight space then you may want to use blown in cellulose for the ignition barrier since it is not going to cause the itching or the health issues I believe. Am I correct guys?

BTW, I learned years ago doing my house with my dad when I was a kid that an old upright vacuum works great for a blower! LOL We just opened the bags, I fed the beaterbar and he had a hose taped to the output side instead of a bag. It fluffed it up nice and blew it out pretty well. That is if someone is wanting to do it themselves on the cheap for that type of insulation. A cheap old vacuum from Goodwill and it was done.

Tim O'Keefe

Posted: Jan 01, 2008 10:03 PM

There are paints that can be applied on top of the foam which meet thermal barrier requirements. http://www.tpr2.com/afes-f1e.htm This is easy to apply in an attic where access is difficult.

Tim
Granite State Spray Foam Co.

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