Attic odor mitigation | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

Q&A Forums

Author	Comments
Robert Jordan Posted: May 16, 2010 07:42 PM	Attic odor mitigation Last June we sprayed 5 inches of closed cell foam in attic rafters. After the initial airing there was no complaint of odor from the homeowner. After a hot day this April, almost a year later, the customer called to complain of an odor. It smelled like foam. The sun was fairly hot the day we sprayed and I imagine the roof deck was hot. Certainly the attic space was hot by the time we were getting to the end. I think it quite likely we put the second pass on too soon. I have been told it could well be 30 minutes or more before the second pass can be applied in some cases. The insurance company is trying to figure out what to do. The homeowner demands the foam be completely removed. Since there wasn't any odor for a year, I wonder if airing the attic out wouldn't get rid of the odor, at least for awhile. The two foam samples I looked at didn't indicate serious problems with the foam, although there were some elongated cells. As a longer term fix, I have proposed putting in an HRV such that the fresh air is supplied to the house and putting it under positive pressure and exhausting the odor from the attic, putting it under negative pressure. If this removes the odor, it also benefits the homeowner with better air in the house. A second suggestion is to apply a Kilz Odor containing primer. Any possibility that this will be effective? A third idea is to strip the shingles from the roof and put down sleepers under a new layer of plywood, and perhaps some rigid foam, to keep the existing roof deck and CC foam from getting hot and causing it to off-gas. Is there anything in the off-gassing that is likely to be harmful to the homeowner? The AC unit and ductwork is in the attic. Turning on the AC increases the odor in the house, indicating the return duct work is leaky and the return itself is undersized. Any liklihood these remedies will work? It is going to be extremely expensive to remove the foam. Furthermore, disruptive to the homeowner. Sure hope there is a reasonable remedy. Finally, How do you know when a second pass can safely be applied? Mason says the foam should be less than 200 degrees. Is this the surface temperature or internal temperature?
mason Posted: May 17, 2010 10:01 AM	You have a lot of questions to answer so I try to answer them with an explanation of what can happen if the foam gets too hot during application and the possible consequences. Foam that exceeds 250 degrees F during its rise and set time can have more open cells than normal I have seen some foam have 50% to 70% open cell content under these circumstances. Additionally some catalysts can be affected by higher temperatures causing them to chemically change into another catalyst that has a stronger odor. Airing out the space where the foam is installed may or may not reduce the odor. But, since it is still causing odor after close to a year, I suspect it would be a short term solution. However, you may be able to identify specific areas of the foam that are causing the odor. Try cutting some samples of foam in various areas, you should get a strong odor from the foam if it is the cause of the odors. Only those areas that are causing the odor need to be cut out. Make sure it is the foam causing the odor. Drywall that was made in China has been known to cause similar odors when heated. As for harmful effects of the odor. The odor can be objectionable to folks, particularly if they are sensitive to chemical odors. Folks with respiratory illness such as asthma may have asthma attacks triggered by strong odors of various types. (including chlorine, ammonia, coffee, etc). Next in order to determine when you can install the next lift of foam. Spray a lift of foam at the thickness you want to install it. Get a digital themometer and stick it into the middle of the foam after it is dry to the touch. It should not exceed 220 degrees F. You can install additional foam on top of the foam lift when the foam internal temperature starts to drop. The thicker the foam pass the longer it takes for the heat to dissipate. 1-2 inch lifts typically take 10-15 minutes for the heat to start going down The thickness you can install foam may vary from day to day depending on the ambient and substrate temperature, temperature of your liquid materials, pressure, gun configuration, etc. So I would test this out before you start spraying. After a while you should know how your brand of foam reacts under various conditions.
Robert Jordan Posted: May 19, 2010 02:47 PM	Thanks for your reply. I wasn't just thinking of airing the attic out for now, I was proposing putting in an HRV so there would be continuous ventilation. Just wondering if anyone has tried to address an odor problem this way with either good or bad reults. I am hopeful that it might work as there wasn't any odor problem for a year (including the heat of last summer). Only when the return of heat this year drove more odor out. To follow your suggestion, is there any practical way to locate the offending areas and remove it? I don't think the entire installation is a problem. There are accessibility issues and the only way I see to remove it is to open up the roof from the outside.

Author

Comments

Robert Jordan

Posted: May 16, 2010 07:42 PM

Attic odor mitigation

Last June we sprayed 5 inches of closed cell foam in attic rafters. After the initial airing there was no complaint of odor from the homeowner. After a hot day this April, almost a year later, the customer called to complain of an odor. It smelled like foam.

The sun was fairly hot the day we sprayed and I imagine the roof deck was hot. Certainly the attic space was hot by the time we were getting to the end. I think it quite likely we put the second pass on too soon. I have been told it could well be 30 minutes or more before the second pass can be applied in some cases.

The insurance company is trying to figure out what to do. The homeowner demands the foam be completely removed. Since there wasn't any odor for a year, I wonder if airing the attic out wouldn't get rid of the odor, at least for awhile.

The two foam samples I looked at didn't indicate serious problems with the foam, although there were some elongated cells.

As a longer term fix, I have proposed putting in an HRV such that the fresh air is supplied to the house and putting it under positive pressure and exhausting the odor from the attic, putting it under negative pressure. If this removes the odor, it also benefits the homeowner with better air in the house.

A second suggestion is to apply a Kilz Odor containing primer. Any possibility that this will be effective?

A third idea is to strip the shingles from the roof and put down sleepers under a new layer of plywood, and perhaps some rigid foam, to keep the existing roof deck and CC foam from getting hot and causing it to off-gas.

Is there anything in the off-gassing that is likely to be harmful to the homeowner?

The AC unit and ductwork is in the attic. Turning on the AC increases the odor in the house, indicating the return duct work is leaky and the return itself is undersized.

Any liklihood these remedies will work?

It is going to be extremely expensive to remove the foam. Furthermore, disruptive to the homeowner. Sure hope there is a reasonable remedy.

Finally, How do you know when a second pass can safely be applied? Mason says the foam should be less than 200 degrees. Is this the surface temperature or internal temperature?

mason

Posted: May 17, 2010 10:01 AM

You have a lot of questions to answer so I try to answer them with an explanation of what can happen if the foam gets too hot during application and the possible consequences.

Foam that exceeds 250 degrees F during its rise and set time can have more open cells than normal I have seen some foam have 50% to 70% open cell content under these circumstances. Additionally some catalysts can be affected by higher temperatures causing them to chemically change into another catalyst that has a stronger odor.

Airing out the space where the foam is installed may or may not reduce the odor. But, since it is still causing odor after close to a year, I suspect it would be a short term solution. However, you may be able to identify specific areas of the foam that are causing the odor. Try cutting some samples of foam in various areas, you should get a strong odor from the foam if it is the cause of the odors. Only those areas that are causing the odor need to be cut out.

Make sure it is the foam causing the odor. Drywall that was made in China has been known to cause similar odors when heated.

As for harmful effects of the odor. The odor can be objectionable to folks, particularly if they are sensitive to chemical odors. Folks with respiratory illness such as asthma may have asthma attacks triggered by strong odors of various types. (including chlorine, ammonia, coffee, etc).

Next in order to determine when you can install the next lift of foam. Spray a lift of foam at the thickness you want to install it. Get a digital themometer and stick it into the middle of the foam after it is dry to the touch. It should not exceed 220 degrees F. You can install additional foam on top of the foam lift when the foam internal temperature starts to drop. The thicker the foam pass the longer it takes for the heat to dissipate. 1-2 inch lifts typically take 10-15 minutes for the heat to start going down

The thickness you can install foam may vary from day to day depending on the ambient and substrate temperature, temperature of your liquid materials, pressure, gun configuration, etc. So I would test this out before you start spraying. After a while you should know how your brand of foam reacts under various conditions.

Robert Jordan

Posted: May 19, 2010 02:47 PM

Thanks for your reply.

I wasn't just thinking of airing the attic out for now, I was proposing putting in an HRV so there would be continuous ventilation. Just wondering if anyone has tried to address an odor problem this way with either good or bad reults. I am hopeful that it might work as there wasn't any odor problem for a year (including the heat of last summer). Only when the return of heat this year drove more odor out.

To follow your suggestion, is there any practical way to locate the offending areas and remove it? I don't think the entire installation is a problem. There are accessibility issues and the only way I see to remove it is to open up the roof from the outside.

You need to login to reply to this topic. Please click here to login.