Removing Spray Foam-Related Attic Odors from the Living Space
suect
| Posted in General Questions on
We live in a nine year old foam insulated home in Texas. Initially the living space had a moldy odor coming from the attic. We have used one 20 pint dehumidifier last fall to reduce the humidity to 40-45% and helped with the moldy odor.
In spring our HVAC company adjusted the fan seed to medium low from the high setting. Our foam began to shrink in the attic so the setting were returned to the high position.
We are noticing a different odor now in the attic and living space. Is there a way to vent this out of the attic so it does not enter the living space?
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We need a little more detail on the composition of the foam, if you know that. To start with - I can't tell from your post if it's rigid or spray foam. I don't know whether it's attached to the roof, or to the attic floor.
Also: Got any pictures of the shrinkage you're talking about?
The spray foam is open cell, sprayed to the the underside of the roof. It has a fire retardant sprayed on top of it. It seems as thought it is the fire retardant that is shrinking, but I could be wrong. The foam looked great prior to the fan adjustments but the fire retardant was a little hard even at that point.
We have an IWave in the the HVAC. It was installed last November. I was assured this would not affect the foam, but am wondering if it has. At that point I was assured the ducts should not leak and therefore it would not have an impact on the foam.
Unfortunately I am not at home to take photos on Monday. Thank you for your reply!
FYI, the IWave looks like it is an ionizer; not likely to be effective, and possibly making things worse. https://www.greenbuildingadvisor.com/article/all-about-air-purifiers
Hi Sue.
It would be wise to determine the source of the odor because venting it out of the house is only part of the solution. While you may no longer be breathing it in, if it is mold causing the odor for example, there may be rot to follow. If it is a spray foam failure, than it is not only smelly, but may not be providing the air sealing and thermal barrier that it was intended to provide.
That said, to deal with the odor, make sure that you have continuous ventilation with a fresh air supply, consider creating an air barrier between the attic and the living space and perhaps pressurize the living space slightly.
Have an experienced contractor to investigate the cause of the problem and recommend a path forward. Mold and spray foam failures are not issues you should put band aids on.
Thank you. We will be having the Ultra Aire dehumidifing ventilation system installed soon with hopes of increasing the ventilation . Our ventilation cycles have been 6 minutes per hour set by the previous owner. We have maintained this due to the heat and humidity here in the summer. We also are receiving mixed opinions of not using a fresh air intake due to the humidity. Recently I played around with the AprilAire fresh intake to learn there were no parameters set. I since then have limited the temperature to 90 degrees and the humidity to 45%. It seems that the higher the humidity downstairs the humidity gets too high upstairs.
So far it has been difficult to find a specialist to review our insulation. Everyone expresses preference for working with installation of new foam only. It would be great to get a few names if anyone is familiar with companies in the San Antonio area.
I appreciate the information you have shared!
Hi I'm from the UK. In some foam is urea. If the smell your getting smells of cats, then it possible that if the foam has also gone a brown colour its the foam breaking down and this can be cause by heat hitting/ humidity and or just old foam. I hope this helps. David
Thank you so much! The smell is not similar to urine, it’s difficult to place my finger on it.
It surprises me this has all occurred since April when the HVAC fan was adjusted.
I'd buy two good hygrometers (humidity meters) - one for the house and a wireless one for the attic (presumably conditioned). 50-60% is good for warm weather, can be somewhat higher in the attic.
Thank you!
I have a humidity reading of 45% on the main level. In the attic it ranges from 49% at night to 58% at the peak of the heat during the day. Temperature in the attic is 75 at night and 85 during the hottest part of the day.
The humidity was much higher when we first moved in a year ago, levels registering in the high 70s in the fall. At that time we had 2 70 pint dehumidifiers on the main level and a 20 pint in the attic. My husband noticed a great improvement with the odor especially when it was below 48%.
Hi!
Here is a photo of last weeks attics readings and main level readings.
Regardless of what is going on in your attic, the only reason you are getting smells from your attic into your living space is because your HVAC is loacted in the attic and ITS LEAKING. You wouldn't smell anything if the HVAC wasn't drawing air in from the attic and depositing it in your living space.
Now that may be by design if your house is intended to have a conditioned attic and there is an air supply line in the attic dumping air up there and an air return there as well. If your house is intended to have a conditioned attic space, then you are going to get an attic smell in your house. When you bake shingles, tar paper, wood, insulation and dust in the Texas sun all day and purposely suck that air into your HVAC and blow it throughout your home, its going to smell.
If you Attic/HVAC system was not designed to condition the attic, then air sealing your ducts will stop the smells from getting into your living space and have the added benefit of lowering your electric bill.
Thank you! I was told we have leaky ducts and was advised they should be sealed by some and not sealed by others. Mastic has been used recently to seal the ducts, but no testing was done.
The original HVAC installer stated recently that the ducts can be leaky as it is a part of the conditioned space. They also spliced into the outside air intake to install the AprilAire ventilation system leaving an open return.
Others again stated this is not good and to seal everything. And close the return.
The open return was closed prior to the foam shrinking...could this be the cause?
Would a small 50 cfm bath fan exhausting air intermittently help along with positive pressure and duct sealing?
The other question is:
Is it okay to seal everything up when it was not set up that way initially?
Thank you!
Heres the thing, yes you could have a problem with foam or maybe with moisture but your immediate problem is the smell is traveling from your attic into your home. Knowing that Texas HVAC guys love to put the HVAC in the attic, the most logical answer to how the attic smell is getting into your living psace is via the HVAC. stop the smell from getting into the HVAC and you stop problem #1.
Its almost as if you go to the ER for a broken leg and the Doctors are all standing around debating if you have bone cancer. Yes the cancer might be worse than the broken leg but fix the damn leg first and THEN worry about the cancer.
Thank you! Locating leaky the ducts Will be a great start.
I recently purchased an infrared camera attachment for my phone. I noticed several hot spots in the foam. One area I could feel the heat and moisture. Could I seal this with Great Stuff? I have reached out to insulators prior to check for this as well, most say it’s a job that is too small.
If it is okay, which product is advised and is there concern about trapping moisture in and causing a greater problem?
Unvented attics need to be conditioned, even if you seal off all the ducts, you would still need to add back vents to get roughly 50cfm/1000sqft of space. So you are back to square one.
Before doing anything, add in the small exhaust fan as recommended bellow. Run like that for a couple of months and see if the smell goes away. The bath fan will also drawn in conditioned air from the house, which is what you want.
As for patching the foam, you can use any of the canned products, they will all work well.
According to this source, foam can shrink 6% (eg, a huge > 1" in 24") when going from hot and humid to just hot. But maintaining high humidity causes mold, so it's not a solution, even if you can avoid smelling it.
I'd make sure humidity is in the correct range and then work on air movement (from hvac, reverse stack effect, etc).
Thank you !
Would 48-58% be the proper range%. We had it as low as 40 percent with a gradual decrease over months in the home and attic, eventually telling that is too low.
Could you help me with Ideas on how how I may reverse the stack effect?
Thank you!
That's a good humidity range. You can install a very small exhaust fan in a conditioned attic to reduce attic pressure. After you address the leaky attic duct issue, this can reduce or stop airflow from attic to the house.
Thank you.
I read the source in your reply. My thought is: the humidity levels were higher when we purchased the home that was 8 years old. Could the foam over expand and now with much lower humidity cause it to shrink to the level that it is now?
Would there be any concerns with sealing all the ducts that were leaky (supply and return)?
I’m hoping with having the humidity a little higher (5% on the main level 5-10% in the attic) there may be A potential for some re expansion? The other thought is would I need to revert back to leaky ducts if it was possibly designed that way? (Or possibly done due to cutting corners?)
Thank you all in advance.
The square footage of the home is 2500. Would 2 - 50 cfm bath fans be advised? Attic height is between 4 to 12 feet (low slope roof).
Currently there may be passive venting around the fireplace exit...can see light. I hope to keep this open until I am able to locate a contractor who is comfortable with installing the bath fans. Some say this is part of the attic problem. Would I be on the right track with waiting on the chimney sealing
Thanks again!
I would install one of these:
https://na.panasonic.com/ca/home-building-solutions/ventilation-indoor-air-quality/ventilation-fans/whispergreen-selecttm-one-fan-multiple-iaq-solutions-50-80-110-cfm-pre-installed-multi-speed
It has small switch inside for setting the CFM of the fan. You can start it out at max and if the smell goes away, you can easily turn it down in stages.
You definitely want to air seal the attic, daylight around the chimney is definitely bad, you want to draw in conditioned air from the house, not humid air from outside.
Make sure to monitor humidity in the attic, you want to keep that near the same level as the house. A dedicated dehumidifier up there might be needed if it gets too high.
Thank you! I will check it out.
Attic temps 75 at night and 84 daytime, humidity 48%nighttime and goes up to 58% during the day. Main level 75 degrees and 45% with a/c. We will have the Ultra Aire set between 45-48% with a 6” and a damper to adjust. Would 45% be too low for both areas?
We will address the chimney. Thanks so much again.
If your humidity in the attic is increasing while the attic gets hotter it means you have moisture inside your foam. Run a dehumidifer up there set on dryest setting to dry it out. I wouldn't adjust the house dehumidifer, the issue isn't there.
Normally one would increase the amount of air from the HVAC, but because of the smell, this won't work.
If the smell does dissipate, you can try this instead of the dedicated de-humidifer.
With proper conditioning of the attic, when the sun hits your roof, the temperature should go up but the RH should go down.
See this article for how to seal around a masonry chimney or metal flue: https://www.greenbuildingadvisor.com/article/air-sealing-an-attic
Thanks so much! I definitely will read this article.
Thank you. I do have a concern that the foam seems to shrink the drier it gets. Would addressing all of the leaks and hot spots help with this? I have been told foam should not shrink but unfortunately it has. I will definitely send photos tomorrow.
I really appreciate all the information shared and will definitely try to locate a contractor who could follow all the information shared. If anyone is aware of someone in the San Antonio area please let me know.
Is it possible that the IWave would have an impact on the foam??
I'm somewhat surprised no one has posted this, but open cell foam in roof bays can lead to condensation above the foam and rot of the sheathing. I'm sure your ductwork doesn't help, either. Search the site for roof problems with open cell foam.
Would this create the odor we are concerned about? We just returned from being away and it is a little on the sour side to me, but not my husband. The moldy smell when we first moved in is gone. We had a rental company suggest using a hydroxyl cleaner for the mold smell, stating it is safe in foam attics. My concern is the areas that lack foam as well and the potential for rot there. Very few will look at this.
Bob,
I check a few of the articles. It would be good to have my attic evaluated as well as being proactive with all the suggestions given. I am in the process of trying to find someone to evaluate. Any suggestions? Insulation, roof, HVAC company...building science expert who May evaluate residential buildings?
The foam is not supposed to be wet, you need to remove the moisture as this can damage your sheathing in the long run. Whether it shrinks or not is irrelevant.
The best way to do this is a stand alone dehumidifer. Try that first before doing anything else. There is a good chance that once the foam dries and you get a bit of ventilation there all the smell will go away.
Open cell is rarely used here, so I can't comment on shrinkage.
Thank you Akos,
Will definitely do this again.
Had it at 40-45% in April by using a free standing dehumidifier. Always higher during the day. The HVAC contractors and insulation contractors were telling me I had it too low...so off went the dehumidifier.
Should I keep the humidity at yge 43-45 % range again?
Thank you.
That is nonsense, put back the dehumidifer and get the foam dried up. The RH should be the same or lower as your house. There is little energy cost difference if you dehumidify the house by running a unit up here more or the main one in the house. You can tell when the foam is dry when the RH doesn't spike up during the day. The humidifier run times should also decrease once this happens.
P.S. I'm pretty sure foam should not shrink from humidity, there might be an issue with the material or application. I would check with the manufacturer to see what they say.
I’ll get them going again. We had a lot of water draining from November to April and the odors did decrease. The hydroxyl machine changed the odor.
Unfortunately the company that installed the foam was bought out and the purchaser does not respond to calls. Nor does the builder... not a good spot to be in while only being here 1 year.
Somewhere in the attic there should be a tag of the installed spray foam product. Call the manufacturer. A bit of persistence will get them to look at it and see if it has issues.
I will check more closely to see if there is one. Thank you!
Hi...Retardant can contain Bromine, this could be also trapping in the mold smell which is Black Mould. Just for interest of your families safety, when fire attacks Poly foam, thats serious however, if the poly foam contains Bromine it will give of cyanate gas, which is deadly. David UK
David,
Would the retardant shrink if too dry? It is very hard on the outer layer but soft underneath.
I have noticed at night into morning that the attic temperature is slightly cooler than the main level and much cooler than outdoors. Any thoughts on this?
Sue,
What you are seeing is night time rediative cooling. Space is a very cold place and it is sucking heat away from your roof at night time. This can cause the roof temperature to drop well bellow outdoor temperature.
This is why it is important to keep the RH in the attic in check. If the roof deck gets cold enough, which can happen even in the summer, any moist air in the attic will condense and cause the wet foam issues you are seeing.
My understanding of this foam application is that Open Cell foam is moisture permeable, as opposed to closed cell foam which is impermeable. Permeable means that moisture penetrates (or "permeates") the foam and is possibly condensing on your roof sheathing. If that is the case, it can and will rot the roof sheathing.
Thank you Akos and Bob!
The humidity is dropping to 53% during the day, 46-48% at night. I have a small fan running along with the dehumidifier.
My concern is this home is 9 years old. We began running dehumidifiers last November (purchased this in Late June last year). Wondering if there had been a great impact already.
My husband was here last summer, stating the odors were brutal. Verbalizes it is by far much better this summer.
Main level has counter sealant that looks dry(concave), boards in the attic were cracking as it approached 45%. Could board shrinking cause gaps that would allow moisture due to outside air meeting inside air?
I’m not sure if this house has ever been this dry. I’m guessing 55% was the norm.
Following advice.
So far I am not able to locate any stickers for foam manufacturer.