Mixed Humid Climate – Closed Cell vs Open Cell Foam
I posed a question this week about mixed humid climates – closed cell vs open cell foam. In a mixed humid climate, do you use open cell foam exclusively or can you use closed cell in some limited places?
In speaking to a very experienced architect on the subject, he hands down believes that closed cell is the answer for the typical wall system design. My problem – I can only find science that refutes his claim.
Closed cell foam is a vapor barrier that will not let moisture flow through the wall system.
In our climate, where we have two seasons, we cannot have a vapor barrier. This is because it will produce moisture issues in the wall. The only way to prevent moisture issues is to include a dehumidification system as part of the HVAC design.
While I do want a dehumidification system in every project, we know they don’t always get installed due to budget cuts. However, the bigger issue is when the building is shut down for a few days. When people go on vacation and cut back the thermostat or schools are out for the summer the system is not running as designed. When this happens, you are going to have a mold problem. I cannot find any science to back up the claim that closed cell foam can be used here in our climate. If you want to give me some data, I would love to be able to achieve the higher R values that the product offers.