Spray Foam Insulation...ready for the big time?

By all accounts, Spray Foam Insulation has the best available insulation properties of any material still in use.*  As well as having good to excellent R value (open cell foam is about the same as fiberglass, closed cell even better), it completely seals a structure from air leaks (closed cell goes further and also seals against vapor and moisture), and remains dimensionally stable over the life of a building (fiberglass batts typically compress over time, reducing their effectiveness, and loose fill insulation settles).  The effect of air leakage hasn't been fully incorporated into standard analysis (R value) which focuses on radiant energy but is clearly very important.

(*Asbestos may have been even better, but has been illegal since the 1970's for public health reasons.)

But despite that, spray foam insulation is not widely used in the large tract home developments I have seen.  Residentally, spray foam is mostly used only in custom construction or remodeling.  And I'm beginning to think that may be a good thing.  While a finished structure with cured insulation is safe for the inhabitants (unless it catches fire) it is not clear to me that sufficient care is always taken to protect spray foam installation installers, and this would likely be even worse with large scale use.  And a major fire in a housing tract where spray foam insulation without fire retardant is used would be a very bad thing (not easy for residents to escape from fumes all around).  And the chemicals used to provide flame retardancy may be actually the most toxic of all for the installers, so that's not necessarily the answer either.

To create spray foam, an isocyanate (usually MDI) is mixed with a polyol, usually in the spray gun itself.  On application, the spray foam is not fully cured, and as a result there are free isocynates in the initial polyurethane foam as well as free isocynates relased from the applicator itself.  It takes several days for the foam to fully cure, during which time additional isocyanates are released.  The polyols are generally not considered as harmful. though they may actually be responsible for most of the smell.  Isocynate is odorless until it reaches very high concentrations normally not seen.

The key health hazard from isocynate is asthma.  Insufficiently protected installers can develop increasing sensitivity to MDI (which is a respiratory irritant) first leading to temporary asthma, then permanent asthma.   If they continue working with MDI after developing permanent asthma, a severe deadly asthma attack could develop.  Unfortunately, when different lines of work are hard to find and especially with the same level of pay, workers may indeed continue working with MDI, covering up their symptoms in various ways.  Here is an account of one worker in the auto refinishing business who persisted in working with isocynate based polyurethane car finishes after doctors warned him not to, and wound up dead.  Isocynate is an essential ingredient in polyurethane of all kinds, though sometimes polyurethane finishes are pre-mixed and considered more safe than those created by mixing the two ingredients on site.  The MDI used in spray foam insulation may be somewhat less toxic than isocynates used in creating other polyurethanes such as those used in two-part finishing products.

Here's is an official report from the State of California about isocynates which echoes the same story.

Now it's true that as a limited and elite industry, with workers required to have training and so on, the hazards of spray foam installation are taken more seriously than hazards in other areas of construction.  For example, all workers who work with cementious and clay siding products and fiberglass insulation should wear particulate filter respirators, but I did not see that done when my building was being built, and I suspect that is all too common.  On the other hand, you will almost always see spray foam installers wearing full body suits with full face respirators.   Unfortunately, sometimes the installers and assistant installers who do the foam scraping afterwards might not.  The extra health precautions often demanded by law for use with spray foam installation are part of the reason for the high price for spray foam insulation.*  But even with an elevated level of protection, it may not be enough.  For example, spray foam installation is best done with supplied air, not respirator filters.  And respirators should not be the first line of defense: the first line of defense should be proper airflow through the workspace.

*Or at least the high price, and limited availability, of spray foam insulation is justified by health concerns, whether or not fully safe methods are used.  The installing company may simply pocket the extra money without putting much into increased safety.

One can only imagine there would be far more occupational asthma and death from spray foam application if it was used in all residential construction as a matter of course.  At least until the safety issues are taken as seriously as they should be.

An additional issue is that subsequent contractors may be exposed to excess isocyanates if the next stage of construction, typically sheetrock installation, isn't delayed for a few days to allow the foam to cure.  In my case, that became part of the plan anyway by coincidence (I have jury duty starting on the Monday after the Saturday foaming), but in the rush-rush residental tract construction business, that delay would probably not happen.

*****

Knowing all this now, I'm not sure I would have specified my insulation.

What I did specify was closed cell foam applied to the full 5.5 inch width of all 2x6 framing, later ammended in a verbal agreement to covering all the rafter supports.  That seemed to me to be the best way to get the maximum energy efficiency possible, and it seemed to be accepted by the general contractor (though the actual contract is vague, the contractor agreed to what I said in an email).

But when the day actually came, the general contractor said all that foam that was unnecessary, and that all the foamers would do would be to apply 1.5 inches of closed cell foam to the walls and 2 inches under the roof deck.  No more was necessary, it would just be wasted.

Well I knew immediately this was wrong and inadequate, and further research backed it up.  Under the roof deck, in particular, local and international residential code specifies R30.  That would require over 4 inches of R6.8 closed cell foam installation, not merely 2.  Also, the R value increases linearly with thickness, and the DOE actually recommends R30 - R60 for residential construction in Zone 2 where I live.

But then the contractor offered me to augment the initial 1.5 and 2 inches of closed cell foam with the cheaper, lighter, and easier to apply open cell foam, up to the full width of the framing as I had wanted, for a mere $1100 extra.  Doing that with closed cell foam would require an additional $3000.

I did some research to confirm that this was OK.  In fact, a number of building consultants have written about this dual-foam approach, one called it an inexpensive way of getting the best benefits of foam, one called it "the best of both worlds" (you get the water vapor sealing of closed cell with the acoustical aborbing properties of open cell), and a major building advisor has said it is OK but he couldn't imagine how it would be cheaper than all closed cell for logistical reasons, thinking different equipment, truck, and crew would be needed, so why not go all the way with the full thickness of the superior thermal insulating properties of closed cell foam?  But he was wrong about that last part, apparently now many foam systems can handle both kinds of foam, switching from one to the other with a mere purging of the hose, and the chemical systems are compatible.

(I'm ommitting here the saga of the two days of spray foam installation, that is a long an torturous story that deserves a separate post.  Actually, the saga continued the next week, as the contractor tried to pass on an additional price increase, and I fought back, and we came to a reasonable settlement.  In the end, I paid only a $635 extra for the 0.5 pound foam on top of the 2 pound foam...though it could be argued I should have paid nothing extra and got the full 5.5 inches of more expensive closed cell I thought had been agreed to.)

The actual spray foams used by my installer, South Texas Insulation, were both made by Gaco Western, apparently one of the biggest names in spray foam you've likely never heard of (you have probably already heard of names such as Dow, BASF, and other major spray foam manufacturers).  The closed cell foam is Gaco Western 183M (the website says 183 but I believe what they used was actually 183M as the description fits better) and the open cell foam is Gaco Green 052.  I inspected the closed cell foam after installation and it is yellow and very hard (the installer pounded on it to show how hard) and the open cell foam was blue and rather flimsy, especially at first.  When inspecting the open cell foam part of the installation, I noticed that the western part of the ceiling looked a little thin.  The installer said that was where he switched foams, and initially that section got a mixture of closed and open cell foams (I'm not sure if that is good!) and because of the high closed cell content, it would actually insulate better than the thicker layer of pure open cell found elsewhere.  The color is also slightly off in that section, a strange yellowish blue (but not green).  I'm wondering if that is correct installation, it might seem that the lines to the spray gun should have been fully flushed when switching from one foam type to the other.  That may represent a kind of installation error, and installation errors are often claimed to be the source of long lasting outgassing problems (while correct installation is said to have outgassing that disappears quickly enough not to be a health issue for subsequent workers or occupants).

Initially, during my inspection soon after foaming and scraping was complete, and a few hours later, the smell was very intense and annoying.  I didn't get any eye watering, chest tightness, or similar allergic issues from brief moments (less than a minute) spent inside.  But even with a healthy breeze and the french doors wide open and the A/C opening uncovered, the smell was intense and annoying.  I smelled it on my shirt later, and decided to wash all clothing that had been worn during my brief moments inside.  I continued the process of washing clothing afterwards on each visit, even washing my two down jackets.  I even had "flashbacks" of smelling the smell with nothing that could have picked it up around me.  I had one brief flashback this morning, in my bedroom, two weeks later.

It was about week later before the sheetrock was installed.  During that week, the smell did go down considerably, and lost the especially annoying quality.  It was still noticeable, though not physically unpleasant, by day of sheetrock installation.  I left the french doors and A/C opening open as much as possible.  I had to close or cover them on Monday January 9th because of rain, but it was only for about 24 hours.  During that time there were two warm days which reached temperatures in the mid 70's, several very cold days, and one hard freeze to 28 degrees.  I figured the warm days and even the hard freeze were good to vent or squeeze all the more toxic chemicals out.

Immediately after the sheetrock was installed, there was no noticeable spray foam smell, or perhaps it was masked by the very strong smell of sheetrock dust.

I'm thinking and hoping now that the 6 days of delay from installation until the application of sheetrock were very fortunate, and I have pre-outgassed all of the really bad stuff so it won't be seeping out slowly from the sheetrock henceforth.  I notice that some building codes require 3 days from spray foaming to sheetrock installation.  One brand of spray foam, Icynene, claims that sheetrock can be installed within minutes of foaming.  I'm wondering if that kind of installation practice explains the issue that one guy had with his dream home project, being forced to sell it because he couldn't move in.

Of course, I don't yet know what the smell will be like after the building is completed, the A/C unit installed, and the french doors left closed for days at a time.  If there is a long term continuing problem, I have found a solution which which would be far cheaper than tearing the whole building down and starting over (since it is nearly impossible to remove spray foam, especially the hard cell kind, from a finished structure).  I could get a $699 VOC filter with 28 pound carbon filter.  Such a filter is said to be able to handle VOC problems for up to 2000 sq ft.  On low speed fan, it would consume about 28 watts.  It might be good to have such a unit to take care of outgassing from the old equipment I plan to store in the building as well.

It may be likely that the highly reactive and volatile Isocynates are long since gone, either they have reacted with other chemicals or materials or simply vented away.  What remains is the residual odor from unreacted Polyols, or other chemicals used, such as the flame retardant.  Historically, fire retardants have been among the most environmentally hazardous materials used in polyurethane foam.  PBDE's had long been used in all kinds of polyurethane foams as flame retardants, they are now banned in many areas.  Humans are now found to contain significant amounts of PDBE's, and this is one reason they have been banned, but this is generally believed to be mostly from eating fish and animals that have been absorbing surplus PBDE's found in the environment as opposed to inhalation from bedding or building materials.

Here is a brochure that says Gaco Western does not use PBDE's in their Gaco Green Foam.  But they don't say what fire retardants they do use.  Icynene goes farther and says they don't contain any brominated compounds.  But one never knows if whatever it is they do use may simply be the 'next' banned chemical that caused serious problems.

I have a theory as to why even the relatively less toxic polyols (often derived from vegetable oils) used in spray foam could cause allergic problems.  Conditioning.  If someone has been exposed to the Isocynate/Polyol outgas mixture, it is initially the Isocynate which causes severe reaction.  Except in very high concentration, the Isocynates are odorless.  What may happen, however, is that operant conditioning either at nervous system level or immune system level associates the polyol smell with the isocynate reacting, so even much later the polyol smell might trigger allergic reactions.