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Posted: Aug 18, 2006 08:07 PM	Existing Attic Question Ok, I have a 1979 house in Wiscosin. I found out that it was not built with a Vapor Barrier. I have replace many roof decks because of this issue. So I set out to get foam insulation. I have also found out that when you tell them that you have newer cellulose few want to do it. I suspect this will change when jobs become tighter with failing economy. But I got on bid to install 3 inches of Comfort foam with an R30 of fiberglass blown over the top. And have talk to a Demilac contractor that would do 3 inches closed cell and 5 of open cell over the top. After all that I have read seems to me that the R30 maybe excessive and the 5 inches also excessive. Just want your thoughts on it being done both ways. I also asked to spray over the rafters. So not to have thermal bleed through. Also are there any advantages over one product or the other?? I also know that Both the contractors will do a great job. So looking for product specificates. Also I do realize one has a high r rating but any others?? Thanks for your time and help.
Melvin Chandler Posted: Aug 18, 2006 09:46 PM	Are you talking about a closed attic assembly/Hot Roof/Semi conditioned attic? If so I'm suprised that a Demilec contractor suggested using Heatlok on the roof deck and then Sealection. Based on my research (somewhat limited) Demilec and one other company are the only two to obtain an approval for the closed attic assembly and that is only with Open Cell. I have closed cell for my building envelop but don't have it on the roof deck for the closed attic assembly. The primary negative that I've found in using closed under the roof deck is when there's a possible roof leak. It could rot the deck before you ever notice a leak. I've not seen that happen but have heard of some cases. Knowing what I know now, I'd do a closed attic assembly with Sealection 500 from Demilec because of the approvals. They are approved (see ESR-1172) up to 6" under the deck but I think they have a new approval (not published yet) for a 10" max thickness. Demilec suggests that 6" should be fine for a closed attic assembly in Wisconsin. I'd check with the local Demilec Rep and code official to confirm the information from the contractor.
Posted: Aug 18, 2006 11:06 PM	No this would not be a closed or a hot roof application. this would be applied 3" of Closed cell would be applied to the sheetrock and then 5 inches on top of the. The sheet rock is the cieling of the house. Also lets say that the rock had a vapor retarding paint. Would that be bad. As in 2 vapor barriers? I don't think it does but was wondering. Anything others??
John Shockney Posted: Aug 19, 2006 09:50 AM	I think that you are looking at the wrong thing if you have replaced roof sheeting caused by condisation damage. The cause is probly a lack of ventlation or other moristure sorces like bathroom vents not exosting to the outside. I have even seen a clothes dryer vented into the atic and that's a fire hazard (dryer lint is highly famable). As to the 2 vaper barriers there should be no problem unless the sheetrock wasn't dry. I would use open cell foam due to cost and it provides an good vaper barrier at anything over 6 inches also if the roof ever does leak it will not trap water. Airpro
Aaron Scurlock Posted: Aug 19, 2006 07:15 PM	What are the advantages of open cell to closed cell for this application? What are some of the disadvantages of open cell? Also both for the closed cell?
Melvin Chandler Posted: Aug 19, 2006 07:35 PM	Advantages of Open Cell: $$$, $$$, and $$$ Less per #, bdft, gal, sf, R ... Open can be sprayed in one pass. Closed shouldn't be sprayed more than 2" in a pass due to the chance of fire from exothermic heat. Open will absorb sound rather than reflect it. If the upstairs is noisy closed could create a loud living space up there. If open is installed where it should be (under the roof deck) it meets the ICC code approval to do so. No closed cell foams can make that claim. Now... I put 2" of closed in my walls and about 2 to 3 inches in my ceiling (installed the attic deck first and sprayed from below but will not be retrofitting attic with open). I haven't had any problems except that my house, which has a lot of wood floors, is loud and could be due to the combination of the wood and dense foam. I've had a few others that used closed and complain of noise. So I'm not so sure about spraying in the attic over the gyp. I would say it would be fine as long as the local BI will sign off on it. I just know that the most advantageous place to install foam in the attic is to the underside of the deck and it must be open cell (only two companies have the approvals to do so). One open cell mfg that has an R of 3.81 per inch had great success with the 10" test in the attic and hopes to be approved at 10" soon for the R38 requirements. However, all of their tests indicate that 5.5" is all that is really necessary for the closed attic assembly even in the northern climates. I think both products will work fine for interior insulation and the positives kind of lean toward the open cell. When you look at the bottom line, it just seems so much more cost effective for the homeowner as well as the installer. And that stuff (at least one particular brand) is beautiful when it is sprayed right with a fan tip.
Posted: Aug 20, 2006 10:38 AM	I have great air flow in my attic according to the contractors I have talked to. I know that this is the biggest concern with moisture issues. Thanks for the info on the open cell vs closed. I had not heard that closed is louder. Do you guys think it would be ok to put 6 to 7 inches in and just call it good?? Maybe go over it with sme cellulose afterward?
Posted: Aug 20, 2006 10:47 AM	I was talking about 6 to 7 of open cell. in the above post.
Melvin Chandler Posted: Aug 23, 2006 10:58 PM	Well, you can nearly spray open as thick as you want. There will be some testing data and approvals out on 10" open cell soon (i hope). I would be willing to spray 6 inches but I'm not in Wiss-sconsin. I think there comes a point where there is a diminishing return at about 5" on open. I know I'd take 5" of open over r38 newspaper any day.
Gerry Wagoner Posted: Aug 27, 2006 12:18 PM	6-7 inches of open cell foam will be fine. There is no problem with applying 3.5" of rigid foam as well. No problem. One advantage of rigid is that it will turn the attic deck into usable space. You can walk on it freely. olger
Posted: Aug 27, 2006 04:59 PM	but hence the delemma... most of my customers are customs with geothermal and all the other amenities,,and they want an energy 5star rateing & REBATEs which for my area is r46 in the attic...7 inches open cell dont get there...yes, i acknowledge the thermal performance of foams...
Posted: Aug 28, 2006 03:01 PM	Ok I have almost decoded on what to do. I think I am going to go with 2 or 3 inches of closed cell. With an R 30 of Blown Fiberglass on top. Just can't decide on if I should go with the 2 or 3 inches. Contractor says that dollar return 2 inches is good. But will take alot longer to get that last inch paid for. What do you guys think?? Is there much advantage to go to the 3 inaches with the Fberglass over the top?? I have read about how you loose up to 50 percent on Fiberglass when you get a 25 degree difference from one side to the next. Would I have that with 2 inches and also with 3? Thanks again you guys have been a great help so far.
John Shockney Posted: Aug 29, 2006 08:31 PM	Blown celulose is better than blown fiberglass due to smaller airspaces traped inside and loses less r-vaule as the temp dropes. I would install as much open cell foam that I could aford. You should be able to get 6inches of 0.5# foam for the same cost as 2inches of 1.9# closed cell foam. For more info on the science involived in the moisture/condisation problem check this link Hope this helps Thanks Airpro
Gerry Wagoner Posted: Sep 03, 2006 09:58 AM	Seriously, I would avoid fiberglass altogether. It is the absolute worst insulation commonly available. It makes a great air filter.. Cellulose is more effective. PStores, if you install 3-4" of rigid foam on the attic deck you do NOT need anything else on top of it. In fact it will turn the attic into usable space, walkable and strong. Either way have fun, olger
Posted: Sep 03, 2006 05:57 PM	Thanks olger..... Also has anyone used Sherwin Williams E barrier paint?? I was thinking about spray it on the sheetrock attic floor before the closed cell. Any issues like reactions with the foam?? And if I do I will be doing it about 16 hours before the foam install. What are your thoughts on that??
Posted: Sep 03, 2006 09:08 PM	spray the least amount of closed cell possible down on the lids to seal the structure and to complete the monolithic thermal shell...stack with less expensive materials to obtain design specs... cap fixtures and insulate caps... foam good

Author

Comments

Posted: Aug 18, 2006 08:07 PM

Existing Attic Question

Ok, I have a 1979 house in Wiscosin. I found out that it was not built with a Vapor Barrier. I have replace many roof decks because of this issue. So I set out to get foam insulation. I have also found out that when you tell them that you have newer cellulose few want to do it. I suspect this will change when jobs become tighter with failing economy. But I got on bid to install 3 inches of Comfort foam with an R30 of fiberglass blown over the top. And have talk to a Demilac contractor that would do 3 inches closed cell and 5 of open cell over the top. After all that I have read seems to me that the R30 maybe excessive and the 5 inches also excessive. Just want your thoughts on it being done both ways. I also asked to spray over the rafters. So not to have thermal bleed through. Also are there any advantages over one product or the other?? I also know that Both the contractors will do a great job. So looking for product specificates. Also I do realize one has a high r rating but any others?? Thanks for your time and help.

Melvin Chandler

Posted: Aug 18, 2006 09:46 PM

Are you talking about a closed attic assembly/Hot Roof/Semi conditioned attic? If so I'm suprised that a Demilec contractor suggested using Heatlok on the roof deck and then Sealection.

Based on my research (somewhat limited) Demilec and one other company are the only two to obtain an approval for the closed attic assembly and that is only with Open Cell. I have closed cell for my building envelop but don't have it on the roof deck for the closed attic assembly. The primary negative that I've found in using closed under the roof deck is when there's a possible roof leak. It could rot the deck before you ever notice a leak. I've not seen that happen but have heard of some cases.

Knowing what I know now, I'd do a closed attic assembly with Sealection 500 from Demilec because of the approvals. They are approved (see ESR-1172) up to 6" under the deck but I think they have a new approval (not published yet) for a 10" max thickness. Demilec suggests that 6" should be fine for a closed attic assembly in Wisconsin. I'd check with the local Demilec Rep and code official to confirm the information from the contractor.

Posted: Aug 18, 2006 11:06 PM

No this would not be a closed or a hot roof application. this would be applied 3" of Closed cell would be applied to the sheetrock and then 5 inches on top of the. The sheet rock is the cieling of the house. Also lets say that the rock had a vapor retarding paint. Would that be bad. As in 2 vapor barriers? I don't think it does but was wondering. Anything others??

John Shockney

Posted: Aug 19, 2006 09:50 AM

I think that you are looking at the wrong thing if you have replaced roof sheeting caused by condisation damage. The cause is probly a lack of ventlation or other moristure sorces like bathroom vents not exosting to the outside. I have even seen a clothes dryer vented into the atic and that's a fire hazard (dryer lint is highly famable).

As to the 2 vaper barriers there should be no problem unless the sheetrock wasn't dry.

I would use open cell foam due to cost and it provides an good vaper barrier at anything over 6 inches also if the roof ever does leak it will not trap water.

Airpro

Aaron Scurlock

Posted: Aug 19, 2006 07:15 PM

What are the advantages of open cell to closed cell for this application?

What are some of the disadvantages of open cell?

Also both for the closed cell?

Melvin Chandler

Posted: Aug 19, 2006 07:35 PM

Advantages of Open Cell:
$$$, $$$, and $$$ Less per #, bdft, gal, sf, R ...
Open can be sprayed in one pass. Closed shouldn't be sprayed more than 2" in a pass due to the chance of fire from exothermic heat.

Open will absorb sound rather than reflect it. If the upstairs is noisy closed could create a loud living space up there.

If open is installed where it should be (under the roof deck) it meets the ICC code approval to do so. No closed cell foams can make that claim.

Now... I put 2" of closed in my walls and about 2 to 3 inches in my ceiling (installed the attic deck first and sprayed from below but will not be retrofitting attic with open). I haven't had any problems except that my house, which has a lot of wood floors, is loud and could be due to the combination of the wood and dense foam. I've had a few others that used closed and complain of noise. So I'm not so sure about spraying in the attic over the gyp. I would say it would be fine as long as the local BI will sign off on it. I just know that the most advantageous place to install foam in the attic is to the underside of the deck and it must be open cell (only two companies have the approvals to do so). One open cell mfg that has an R of 3.81 per inch had great success with the 10" test in the attic and hopes to be approved at 10" soon for the R38 requirements. However, all of their tests indicate that 5.5" is all that is really necessary for the closed attic assembly even in the northern climates.

I think both products will work fine for interior insulation and the positives kind of lean toward the open cell. When you look at the bottom line, it just seems so much more cost effective for the homeowner as well as the installer. And that stuff (at least one particular brand) is beautiful when it is sprayed right with a fan tip.

Posted: Aug 20, 2006 10:38 AM

I have great air flow in my attic according to the contractors I have talked to. I know that this is the biggest concern with moisture issues. Thanks for the info on the open cell vs closed. I had not heard that closed is louder. Do you guys think it would be ok to put 6 to 7 inches in and just call it good?? Maybe go over it with sme cellulose afterward?

Posted: Aug 20, 2006 10:47 AM

I was talking about 6 to 7 of open cell. in the above post.

Melvin Chandler

Posted: Aug 23, 2006 10:58 PM

Well, you can nearly spray open as thick as you want. There will be some testing data and approvals out on 10" open cell soon (i hope). I would be willing to spray 6 inches but I'm not in Wiss-sconsin. I think there comes a point where there is a diminishing return at about 5" on open. I know I'd take 5" of open over r38 newspaper any day.

Gerry Wagoner

Posted: Aug 27, 2006 12:18 PM

6-7 inches of open cell foam will be fine.

There is no problem with applying 3.5" of rigid foam as well. No problem. One advantage of rigid is that it will turn the attic deck into usable space. You can walk on it freely.

olger

Posted: Aug 27, 2006 04:59 PM

but hence the delemma...
most of my customers are customs with geothermal and all the other amenities,,and they want an energy 5star rateing & REBATEs which for my area is r46 in the attic...7 inches open cell dont get there...yes, i acknowledge the thermal performance of foams...

Posted: Aug 28, 2006 03:01 PM

Ok I have almost decoded on what to do. I think I am going to go with 2 or 3 inches of closed cell. With an R 30 of Blown Fiberglass on top. Just can't decide on if I should go with the 2 or 3 inches. Contractor says that dollar return 2 inches is good. But will take alot longer to get that last inch paid for. What do you guys think?? Is there much advantage to go to the 3 inaches with the Fberglass over the top?? I have read about how you loose up to 50 percent on Fiberglass when you get a 25 degree difference from one side to the next. Would I have that with 2 inches and also with 3? Thanks again you guys have been a great help so far.

John Shockney

Posted: Aug 29, 2006 08:31 PM

Blown celulose is better than blown fiberglass due to smaller airspaces traped inside and loses less r-vaule as the temp dropes.

I would install as much open cell foam that I could aford. You should be able to get 6inches of 0.5# foam for the same cost as 2inches of 1.9# closed cell foam.

For more info on the science involived in the moisture/condisation problem check this link

Hope this helps

Thanks Airpro

Gerry Wagoner

Posted: Sep 03, 2006 09:58 AM

Seriously, I would avoid fiberglass altogether. It is the absolute worst insulation commonly available. It makes a great air filter..

Cellulose is more effective.

PStores, if you install 3-4" of rigid foam on the attic deck you do NOT need anything else on top of it. In fact it will turn the attic into usable space, walkable and strong.

Either way have fun,

olger

Posted: Sep 03, 2006 05:57 PM

Thanks olger..... Also has anyone used Sherwin Williams E barrier paint?? I was thinking about spray it on the sheetrock attic floor before the closed cell. Any issues like reactions with the foam?? And if I do I will be doing it about 16 hours before the foam install. What are your thoughts on that??

Posted: Sep 03, 2006 09:08 PM

spray the least amount of closed cell possible down on the lids to seal the structure and to complete the monolithic thermal shell...stack with less expensive materials to obtain design specs...

cap fixtures and insulate caps...

foam good

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