According to the EPA, exposures to spray foam's key ingredient, isocyanates, and other SPF chemicals in vapors, aerosols, and dust during and after installation can cause asthma, sensitization, lung damage, other respiratory and breathing problems, and skin and eye irritation.  Furthermore, isocyanates can trigger a severe and potentially fatal asthma attack in sensitized persons if exposed to even very low levels of isocyanates.

As I understand it, these chemicals are release while spraying the product, as the product cures, and as the cured product off-gasses.

Contractors are supposed to have homeowners leave their home during the spraying of the product and not return until the cured and finished off-gassing and the home has been ventilated sufficiently to reduce chemical concentrations in indoor air to a safe level.  Both the EPA and American Chemistry Council have posted guidance on this topic.

I've called the manufacturer of the product we spray and was told that they have no published guidance on estimating re-occupancy time because there are too many variables involved (amount of product, amount of ventilation, sensitivity of the occupants, ...).

It appears the only way to know if the home is safe after spraying is to take air samples and send them to a lab.  This adds to the number of visits to the home, the final cost to install the product, and the length of time the homeowner should leave their home (at least until the lab tests come back).

I don't think clients are going leave their home for a week just so we can spray their sill boxes and I doubt that they will pay for the added costs of air testing.  However, I want my clients to be informed of the risk and I want to protect my home performance business from liability.  

Is anyone familiar with a liability waiver specifically designed to both inform occupants and protect contractors from liability when spraying this product?

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It appears the only way to know if the home is safe after spraying is to take air samples and send them to a lab. This adds to the number of visits to the home, the final cost to install the product, and the length of time the homeowner should leave their home (at least until the lab tests come back).

Forgive me but - Bull $$$$

New construction - no issues

Remodels - healthy or sensitive I would recommend they enjoy a hotel for the night if you do an entire attic, or fill the walls (of course they shouldn't be there when the spraying is happening anyways). For real sensitive people they shouldn't be in the house while ANY work is happening & they would be best enjoying a hotel for two nights after everything is finished. You should also plan on using one of those negative pressure machines & cracking all the windows. In many cases it might not even be the chemicals but everything else that is kicked up when the work happens.

As for curing & off gassing times, it does vary by the manufacturer & is something you should ask about - but generally after the initial spray & set you aren't going to have any more off-gassing unless it is a cheap product or the installer did something very wrong

As for liability waivers - worthless in most cases, the best advice is to ask about health issues & advise them that OSHA, the manufacturer, the installer, etc... require that the house be empty when installing & they should plan on...

I'm not sure what you are referring to as BS. 

I know that air sampling is not practical and don't intend on undertaking this approach.  However, manufacturers are not going to give specific guidance so all the decision making, responsibility AND liability falls on the installing contractor.  At least with having clients sign a waiver, it provides evidence that we informed them of the health hazard and re-occupancy issue.  That should provide some liability protection.

It seems like a good idea. While as Sean points out these waivers are often shot apart in court, however it serves as a trail to inform and might provide protection in the event of litigation.

With the foam being used in this application for as little time as it has I don't think we know of all the potential problems that could be associated with its application and use. In our litigious society it would seem wise to protect your interest when and however possible. I would suggest looking into an umbrella policy for not just this issue but as a general add on.

That being said for those that can afford it foam provides a double whammy of increased insulation performance and air sealing in one product application. I have not heard of any problems to date that would make me not recommend the product. Whatever off gassing potential should be mitigated by proper installation.

Its ability to seal the space and improve overall air quality should be a net positive to those that are sensitive.

It would seem that you need to speak to another person at that company and or find a new vendor. The answer you have now seems unacceptable. With no guidelines we are all simply guessing.

You are right about the significant cost for air sampling.  As an Industrial Hygienist, that is primarily what I do for a living (in addition to home performance audits) - we are the experts in indoor air quality and chemical exposure evaluations.  Just for aldehyde and isocyanate lab analysis profiles alone, the lab fees only (i.e., NOT INCLUDING LABOR for 4+ hours of testing + report) will run over $850 for testing 1 area only. That does not even include some other VOCs that EPA mentions, such as amines (unspecified types).  This testing could easily run into $2000 to $3000 for testing multiple areas in the home, not to mention at least a week or more delay between doing the tests and getting the results + report before the homeowners could move back in.

To make matters worse, there are no residential standards for "safe" levels in a home, only OSHA standards for industrial exposures to these.  And since several isocyanates and aldehydes are potent allergens, some people could be greatly affected even at or below the OSHA limits.

Therefore, the foam manufacturers really need to develop some better guidelines on how long to wait because testing is not a practical or cost-effective solution to determine reoccupancy.  It could only be used to document that levels were reasonably low (but not necessarily 100% safe for all) at some point in time afterwards; or conversely by an attorney for the homeowner to show that levels were not safe enough when the people moved back in.

I am glad to see a discussion of this topic.  Before becoming an energy auditor, I worked for 10 years as a sculptor in the movies.  We used vast quantities of two-part foam for various set-building purposes, in what would be considered an industrial setting.  As a result, we were very much aware of OSHA guidance on off-gassing of iso-cyanates.


One thing to note, which few retrofit installers seem to know, is that there are NO filter cartridges made by man that will filter out iso-cyanates.  The cartridges are very effective for other organic and inorganic vapors but not this.  A postitive-pressure fresh-air supply is the ONLY thing that will fully protect the installer.


As for off-gassing, this will continue for months, if not years.  There is no getting around that, though obviously the rate of off-gassing drops off dramatically after a day or so.  I believe clients should be warned of this fact and be given the choice of whether they want this product used in their home, especially if it will be used within the conditioned space.

Thank you for sharing your experience.

With regard to filter cartridges, I too had heard they didn't work for isocyanates.  However, I researched it further and found this document from 3M that says that OSHA has provided clarification and states that organic filters can be used provided that appropriate change schedules are implemented for the filters:

Then, I called technical support at 3M to determine what an appropriate change schedule would be for our situation (spraying sill boxes and an occasional rubble foundation).  I was told that the filter should safely last for 8 hour of use provided that we use 6051 organic/vapor filters and 5000 series particulate filters.  I was also told to NOT use the organic filters with the pink covers.  The few thin slits in the pink covers can easily clog up long before the organic filter needed to be changed.

The clarification from OSHA that 3M has referenced can be found at:

You can also find a wealth of information on regulations pertaining to isocyanate at:

Correction: 6001 organic/vapor filters

Thanks for that information, Dmitri. 

I think I still wouldn't trust a cartridge to protect me.  I also feel that OSHA was being very politically cautious in their statement, vague to the point of saying nothing really consequential at all.


BPI has an article about this subject:

They [BPI] direct those involved with the product should visit for information and direction.

As someone who has worked for a manufacturer, and in partnership with manufacturers; (none in this field), I would advise you to not hold your breath regarding specific time guidelines for safe occupancy.

There are just too many variables. For example: installation & maintenance practices, proper mixes or batches of the product, ambient and substrate temperature and humidity, air exchange rate of the area where it may be applied, enormous differences among people regarding sensitivity or tolerance of the product, and of course our personal favorite; lawyers.

If a manufacturer gets too detailed in providing a "safe" time to re-occupy the home and one in a million homeowners happens to be the parent of a newborn with a yet-to-be-diagnosed pulmonary ailment that could be totally unrelated to the job, then nobody wins. Except the lawyers.

It seems to me that the best approach is to direct the homeowner to relevant documentation, offer your past experience (as opposed to advice) and have them accept responsibility for re-entry when they feel comfortable doing so. I would say that everybody has different tolerance levels and they should walk through the house to determine if they are ready to return. 


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