I’m very disappointed to STILL see no LEED credit address moisture management in building envelope design.  As our industry is adding continuous insulation (for good reasons), there are more and more buildings suffering from the unintended consequences of trapped moisture due to a lack of proper hygrothermal analysis during design. This is very common on the type of retrofit project associated with LEED O+M. This impacts energy efficiency (wet insulation = bad insulation), material durability (wet material gets replaced more frequently), and indoor air quality (mold), and yet LEED is still completely silent on the topic of good building enclosure design.

Managing moisture through good BE design is not covered in other credits (wet insulation is not accounted for in energy models, material credits or IEQ – construction moisture management is different than what I’m talking about). 

To address this critical issue, there should be a credit (in MR or IEQ) that simply requires compliance with ASHRAE 160 for all above-grade wall and roof assemblies that cover at least 10% of their respective assembly type’s total surface area. ASHRAE 160 assesses the Mold Index value (predicted mold growth) of the critical material layers in a building enclosure assembly, and is considered the industry standard for hygrothermal analysis. It is very possible to meet IECC/ASHRAE 90.1 U-factor requirements and IBC 1404.3 vapor retarder requirements but still grow mold in walls - this is where ASHRAE 160 comes in to play, and it is also where LEED should come in to play.