March 2, 2015

Is Foam Evil? A New Paradigm of Foam – Less is Best



“Is Foam Evil?” was the initial title of a panel discussion I participated in at NESEA’s Building Energy 15 Conference – before it was renamed “Tiny Bubbles” (see Green Building Advisor’s highlights toward the end of this article). Here at 475 High Performance Building Supply, we are famously anti-foam, with particular emphasis given to closed cell spray polyurethane foam (ccSPF). In our blog series Foam Fails, we’ve taken an extended look at the problems of foam insulation. We’ve even written A Declaration of Independence from Foam Plastic Insulation, that in the style of our Founding Fathers, makes the case against foam and the companies that push it. Each day we are reminded of the performance problems of foam, whether it’s another building burning, or another failed blower door test.

Foam has real baggage in terms of health risks and performance challenges. Foam ingredients are toxic and highly sensitive to environmental conditions. If you spill enough of the Part A-MDI, the industry recommendation is to call the Superfund phone number. Installers should be using air supplied respirators and fire fighters are threatened with hydrogen cyanide combustion gases. If that wasn’t enough, for the foam to cure properly, a dizzying array of criteria must be met on the construction site and evaluated by construction workers that often lack adequate training. If the mix is off and curing isn’t complete, off-gassing can continue, potentially making the building uninhabitable. Good riddance.

We have other choices. For thermal insulation: use cellulose, mineral wool, wood fiberboard or fiberglass. For airsealing and vapor control: use membranes, sheathing, and tapes. Where there are viable alternatives to foam they should be pursued (and we love highlighting projects that do).

But despite all the negatives of foam – and despite all the available alternatives to foam – even we are willing to admit that foam isn’t going away completely. And *gasp!* in a few instances it might actually be useful.

Therefore we aren’t concerned with eliminating foam use outright, but instead we want to radically reduce its use. There is no reason to encase our buildings, our families and our co-workers in a foam-based enclosure any longer. We can remove 90% of the foam in construction very easily, and have a better building and environment as a result (see a recent example at Dartmouth College). What remains? Hopefully just foam in architectural components such as structural thermal breaks, mechanical equipment, and fenestration details. Less is best.

One architectural component that has gotten the right idea are Passive House windows and doors that use wood fiber insulation as a thermal break material and abandons the foam altogether. We like that.

The new paradigm is: Push toward foam-free construction with only very targeted and limited applications remaining.  

Think of foam use like radiation treatment. Sure, radiation can be useful, but its recommended use is limited and targeted.


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11 Responses to Is Foam Evil? A New Paradigm of Foam – Less is Best

  1. Ron March 10, 2015 at 2:54 pm #

    My house is a 12′ x 30′ all metal building. Currently, there is regular fiberglass insulation in the walls and ceiling. There is definite moisture from condensation, in the walls. What would you guys recommend as far as the right kind of insulation I should be using in the walls and ceiling.

    • Ken March 12, 2015 at 8:43 am #

      Hi Ron,
      It may be more a matter of air and vapor control, than the insulation type. What climate are you in? We are happy to help figure it out.

      • Bill Nickerson May 1, 2015 at 8:17 am #

        You should direct Ron to BSC new reports on condensation in walls. You are right about air and vapor.

  2. Curtis Hinksman March 10, 2015 at 3:08 pm #

    Wow. I cant believe that you guys think that is a good story to publish. I think I will be stoping my emails from you guys

    • Ken March 12, 2015 at 8:46 am #

      Hi Curtis,

      Not sure what you are reacting to. The headline is provocative to be sure – but it is merely asking a question and it is in reference to the naming of an event. The post goes on to be fairly measured if pointed in our questioning of the widespread use of foam. And while you may take exception this post, we do hope you find our posts useful in general.

  3. Bill March 10, 2015 at 3:13 pm #

    It depends on what you mean by “foam.” XPS rigid insulation is foam and we used it under ground as part of our rubble trench / frost protected shallow foundation (FPSF). Living in a cold climate, the FPSF saved us from having to pour a 4′ deep frost wall. I know of no foam-free insulation material, except maybe FOAMGLAS, that could have been used with the FPSF application.

    • Robert Haverlock September 21, 2015 at 4:00 pm #

      Why not foamglass, well of course, except cost?

  4. Bob Swinburne March 11, 2015 at 1:50 pm #

    Excellent and balanced. Minimize – as with PVC.
    Local builders here in VT are increasingly making use of EPS foam instead of XPS foam for below grade applications and non foam insulation products for all above grade applications.

  5. Ken March 12, 2015 at 8:58 am #

    Hi Bob,
    Glad to hear of it – there are many great leaders in Vermont doing more sustainable low-energy buildings!

  6. Robert Haverlock April 30, 2015 at 7:44 pm #

    Foam glass will work just fine, except the cost! None-the less, much much better…and , has been used for years commercially…

  7. Fergus Byrne May 1, 2015 at 4:56 am #


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