Posted: August 18, 2016

Keep sending your flood related questions to Paul’s House Facebook Page.

Here is one related to walls with spray foam insulation….

Question: I have spray foam insulation in my walls, but I don’t know if it’s open cell or closed cell spray foam. How can I tell the difference and how do I address the moisture?

Answer: 3 different types of spray foam insulation can be installed in homes – Open cell; Closed cell; Hybrid foam.

Below is an explanation of how to tell the difference and their characteristics:

1. Open-cell spray foam is soft to the touch and can be easily depressed with your fingers, leaving an indentation or hole in the foam.
   • Any open cell foam exposed to flood waters, that is wet, must be removed. Measure the moisture content of the foam with a moisture meter to determine how much of the wall insulation must be removed. Anything that is over 15% moisture content must be removed.
   • The open cell foam will absorb and capture the contaminants that were in the flood waters.
2. Closed cell spray foam is hard to the touch and cannot be easily depressed with your fingers and will not leave any deformations in the foam unless you apply a large amount of pressure with your finger. Closed cell foam is similar to the foam used inside an ice chest.
   • Closed cell foam insulation normally does not absorb water and under most situations will not have to be removed. However, it is wise to measure the moisture content with a moisture meter to verify it is dry (below 15% MC). If dry, then move forward with disinfecting the wall surfaces; applying a biocide and/or antimicrobial product to all surfaces including the closed cell spray foam insulation. See further details here.  
3. Hybrid spray foam’s density is in-between the open and closed cell foams. These types of foams are usually sucrose based foams and their density will vary depending on manufacturer’s formula.
   • Hybrid foam insulation will absorb water and flood water contaminants similar to open cell foams. – Follow open cell spray foam guidelines stated above.

The aim is to remove any spray foam insulation that is wet or will prevent any wood surface from drying in a timely manner. When measuring moisture content with a moisture meter it is best to use the pin type meters that penetrate insulation and wood surfaces.  The pins should penetrate and measure the moisture content at all depths of the assemblies. Every moisture measurement should be below 15% moisture content before closing up the wall assembly with either new insulation and/or drywall. Pin-type moisture meters can be purchased on Amazon for under $40.  

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