“Alexa™, What Building Type Today has the Most Risk of Moisture and Mold Problems?”
Published by Richard Scott, AIA on March 9, 2017
“Hmm, let me think about that. Here is what I found: According to Liberty Building Forensics Group (LBFG) they have been seeing an alarming trend in moisture and mold problems in new low to mid-rise wood frame multi-family buildings.”
With improvements in wood framing technology, there has been a remarkable increase in using wood for low to mid-rise apartment buildings, dormitories, and residential condominiums. Often the first floors are podiums of steel frame, but upper floors are exclusively wood structure. Mold and moisture problems during construction are showing up due to external influences (rain) as well as internal sources (wet applied materials). Contractors must deal with repairing damage and remediating the mold to satisfy risk averse owners/developers/lenders.
Rain damage is difficult to avoid during framing, decking, and sheathing work before buildings are dried in.
Wet applied materials such as gypsum based flooring are easier to control than weather but have resulted in moisture and mold damage as well. Increasing attention to sound reduction has led to thicker floors and sound mats between the floor and wood subfloor. These changes have increased drying times altering the schedule when other construction, including casegoods, trim work, and flooring, can be installed.
Premature installation of millwork, such as case goods and trim, has resulted in thousands of dollars in damage. The enclosed unventilated bases of casegoods becomes a humid microclimate from the drying gypsum based flooring resulting in ideal conditions for mold growth on the concealed surfaces of the casegoods as well as on the gyp-crete itself. Some solid wood materials, such as pine trim, can often be cleaned but the cost of removal to clean back surfaces usually makes replacement a cheaper option. Casegoods are usually constructed from particle board which is difficult to almost impossible to properly clean. Replacement of casegoods is often the cheaper option if schedule allows.
Contractors need to have action plans in place to deal with rain events that wet construction subject to mold growth. Quick action including possible mobilization of drying equipment is critical. Materials need to be dried before mold has a chance to grow. Once mold growth starts the cleaning efforts become exponential.
Longer drying times should be scheduled for gypsum based flooring that is thicker than standard, has sound mats, and/or is installed during rainy or humid seasons. Industry Information on what is considered “dry” for gypsum based flooring is spotty. However, checking it with a scanning type moisture meter should be considered to see if it is in the “dry” scale before installing trim work and casegoods. Consider adding ventilation to the interior spaces (if the ventilation source is not humid air). It may be wise to leave toe kicks off cabinet bases, if the base construction allows, until it is known the gypsum based flooring has dried. Checking relative humidity in interior spaces may also help to determine if gypsum based flooring has dried enough for mill work installation.