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Green Communities

Concerns When Using Spray Foam in Retrofits

Protecting workers during and occupants after retrofits involving spray foam insulation installation is essential

Icynene spray foam insulation installed in a basement wall. The excess spray foam in the stud wall was shaved off while the foam at the rim joist was not.
Image Credit: Peter Yost

Both closed- and open-cell spray foams are used widely to improve the thermal performance of existing homes. Installed properly, it’s hard to beat spray foam’s contribution to air tightness and R-value. But we need to keep our eyes on three important issues: quality installation, worker protection during installation, and safe re-entry times.

How spray foams work

Spray foams all involve a two-component chemical reaction with a “Side A”—primarily containing isocyanates—and “Side B”—primarily containing polyols and a blowing agent). There are three types of spray foam and all involve some level of toxic ingredients, reactivity and curing, and therefore all require quality installation, worker protection, and safe re-entry time.

Quality installation

It’s critical to get the mix and mixing process just right to get the best performance from the spray foam and to limit or eliminate the possibility of un-reacted components. Make sure that your spray foam contractor is employing a quality control program, such as the Spray Foam Quality Control – Canadian Installation Requirements or the ABAA Quality Assurance program.

Worker protection

Whether you are installing spray foam as a part of your general contracting work, you are a full-time spray foam installer, or a do-it-yourselfer, you need to follow worker protection protocols. Repeated or long-term or acute initial exposure to unreacted components or off-gassing during uneventful correct installation of spray foams must be avoided.

Safe re-entry times

This is the toughest part of using spray foam—knowing when to recommend your clients can get back into their home or work space. First, no one should anywhere near the area of spray foam installation without protective gear. And we simply don’t know, exactly, what the safe re-entry times should be for various types of spray foams and different occupant situations (such as schools with more vulnerable children). Some manufacturers are recommending 24 – 72 hours before re-entry for two-part foams and 8 – 24 hours for one-component spray foam. But clearly more research is needed to better understand the best approach for site-applied spray foam installations. Consider both the EPA information on safe re-entry and information from Spray Foam Health and Safety.

While industry works on new spray foam formulations that are less problematic than current technology, apply current best practices for worker protection, installation quality, and safe re-entry.


  1. Joe Schmo | | #1

    Other concerns or guidance
    This may be a bit off topic or perhaps a good topic for a future post, which is guidance on certain challenges or concerns that may come along with the installation of spray foam in existing structure. For example, proper ventilation. I am considering spraying the underside of my roof during a future renovation of the second story of my 1940s cape cod but I believe I may need to install channels (before spraying) for air from the soffit vents to make it to the gable vents.

    Another concern is filling various cavities with spray foam not knowing exactly what is in the cavity. Old or even new wiring, for example, could become overinsulated and become a fire hazard. One phenomenon is known as wet tracking. See:

    Obviously proper installation is key but it would seem that this would transcend into other aspects of the installation as well. Just some food for thought I suppose.

  2. Buildingwell .org | | #2

    Proper Planning
    This article and Brian M's comments bring up great points - the need for proper planning. While spray foam is a great option for existing buildings, it has its problems. Through proper planning and preparation, this insulation type can be great for the building and its occupants and the problems can be mitigated.

  3. 5C8rvfuWev | | #3

    canned stuff?
    Are there any precautions to follow using the canned stuff to seal around windows, doors, etc., when you pull trim in a reno? What about air sealing in an attic -- or is "spot" use of foamy stuff not a concern?

  4. Aj Builder, Upstate NY Zone 6a | | #4

    Brian, very informative link.
    Brian, very informative link. I have recently run into circuits in need of less loads to stop breaker tripping. And this is worse now than ever. Hair dryers and curling irons going all through a home. Electricians that put multiple bathrooms on one circuit. And the customers are being "trained" to shed just enough load so the breaker stays on. This must mean that more and more we are running max amps through our cables and therefore there must be over heated wiring on many many homes just waiting to find a weak spot. Thankfully most homes do not have electric fires.

  5. Keith Gustafson | | #5

    I think the rarity of fires
    I think the rarity of fires involving romex, or with causes related to it calls into question the testing methodology. If wire temps in an uninsulated wall are routinely over boiling point, you are going to smell it. Apparently there are real world conditions that prevent the situations seen in the lab. Among those might be that the devices we use in homes cannot function with the voltage drop associated with pulling current through an undersized wire.

  6. Robert Quesnette | | #6

    free foam education class
    My name is robert and I'm the northeast sales manager for a large foam manufacturer. You can reach me at 860-933-7076. Our company offers AIA as well as educational spray foam presentations at no charge. If after reading all of the articles you're unclear or uncertain on any aspect of spray foam please feel free to contact me.

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