Foam Insulation and the “Moisture Myth”

Moisture Problems with Fiberglass

I ran into a fellow contractor while I was at the bank just now.  I inquired about a job Energsmart had bid on for a beautiful new home on the Niagara River.  He replied that the owner had chosen to go with fiberglass.  I then asked how the homeowner came to his decision.  They indicated that the homeowner had heard about how “all the houses getting foamed were having moisture problems.”

I knew immediately that I had to write a blog post when I got back to the office.  It really fires me up when people spew out such nonsense just because they heard it from someone else who heard it from someone else.  The statement that these houses are having moisture problems just isn’t true.

After tightening a house with foam, it is possible that house could experience an increase in moisture levels if it isn’t managed properly.  We’ve had only two complaints out of 1,200+ jobs about moisture levels in homes we’ve insulated.  In both cases, the homeowner had moisture buildup on the windows.  After asking the owner a handful of questions we found they weren’t ventilating their home properly. 

For example, they would take showers and not use the bath fan to evacuate the steam.  Other characteristics of homes that could increase moisture levels include not using fans for cooking, ventless gas appliances, and high levels of house plants.  Problems caused by these characteristics are very rare and minor.  The situation can usually be remedied by using a simple bath fan to carry moisture laden air out of the home and fresh air into the home.

So, in summary, be careful about what you hear on the street.  The source of 100% of these comments are from insulation companies that don’t offer foam.  If someone tells you any of this nonsense about moisture problems, ask them for a name and number of the person it happened to.  I’ll take a bet any day that they won’t be able to supply it.  No one at Energsmart has firsthand knowledge of an issue with any foam installer that wasn’t extremely minor and able to be resolved inexpensively.   We install this product for a living and if these problems were happening we would most definitely be hearing about it and we’d likely be heading out of business.





5 Responses to Foam Insulation and the “Moisture Myth”

  1. Drew says:

    I can definitely vouch for what John and Energsmart are saying about this. If the walls and attic have been treated with spray foam, you shouldn’t have any moisture issues. Insulate with fiberglass improperly, and watch what happens when you get outdoor and indoor air mixing: you’ll have a moldfest over time. And mold abatement is going to cost an awful lot more than having foam insulation sprayed in the first place. Good post guys.

    • jbartlo says:

      Thanks for the feedback Drew. We appreciate it!

    • Marianne says:

      This information was very uulsfel, but is there anyone out there that can help me with a graph which shows your r-values at the bottom and then your heat loss percentage on the left hand side starting from 0% up to 100% I need it for a project that I’m working on.

  2. LE says:

    The provider I used for my foam job does not have a blog, but having read your comments above I though I would provide a perspective from an experienced consumer. In December of 2010 I had an existing home foamed by one of the largest foam providers in my area.In the 8 months that have followed I have experienced, on average, less than 50Kw decline in monthly usage in energy. There have been no significant changes in the electrical use do to new appliances, TV’s computers etc. that would increase the load. Humidity in the house has not been an issue per say, however humidity in the attic has. Increased Humidity in a foamed house, as I understand it, is usually the result of the A/C not being properly sized for a foamed house. That is if the sizing is incorrect the a/C will not run enough to remove the excess humidity.

    I live in a very high humidity area, south Louisiana surrounded by water. When built in 2002 the house was fitted with eave and roof vents as well as supplemental venting with an exhaust fan in selected areas. Insulation wass provided by 8″ of FG batting with a vapor barrier against the sheet rock. When the house was foamed the vents (all) were sealed with foam. Open Cell was recommended/used because of the high level of expansion and contraction and because I was told that the closed cell can hide a roof leak until the problem is much worse. The result is a relatively cool but very damp attic. The problem , I believe , lies in the retrofit application. In new construction or major renovation where the walls and ceiling are all open, a full envelope is more easily achieved. In a retrofit it is virtually impossible to seal everything. The result is humidity migrating in and has no place to go but condensate.

    The solution is now to condition the air in the attic as well.

    I share this with you because while I still believe in the product (foam Insulation) for new construction, in a retrofit application I find the ROE very low, if not nonexistent, save the fact that can now go into the attic in the summer and not die of the heat. I’m just not sure I do that enough to warrant the $4K it cost me.

    If you are not building new or in a position to ensure a full sealing, be cautious and be sure to talk with a qualified HVAC mechanic as well as your insulation contractor before spending your hard earned money

    • jbartlo says:

      Thanks for your comment and input. Unfortunately, not all companies and installers have the right experience or know-how to get jobs done correctly. I’m sorry you had to spend additional money to fix the problem, but hopefully it’s all fixed now and you can enjoy the results!

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