Case Study: Log home beam mold caused by incorrectly installed dehumidifier

A Clarksville homeowner discovered visible mold growth breaking out across a wooden beam that ran through her log home's living area and kitchen. The beam was a prominent architectural feature—and now it was covered in mold that couldn't be ignored.

She'd already had testing done that confirmed mold was present, so she called Claro ready to move forward with treatment. But during the inspection, the team discovered something critical: her AC/dehumidifier system had been incorrectly installed and wasn't controlling humidity properly.

Claro's team performed moisture readings throughout the home to understand the extent of the problem. Some floor areas registered over 20% moisture content—well above acceptable levels. Most areas were around 5%, which was normal, but the elevated readings in certain spots pointed to ongoing humidity issues.

The crawlspace inspection revealed the bigger picture: lots of the timber showed mold growth, though it hadn't reached a critical state yet. The incorrectly installed dehumidifier meant the crawlspace humidity had been elevated for an extended period, creating conditions for mold to establish itself on wood surfaces throughout the structure.

The homeowner was advised to correct the dehumidifier installation first—otherwise, the mold would simply return after treatment. Once the humidity control system was properly functioning, Claro could treat the home knowing the moisture source had been addressed.

After the dehumidifier was correctly installed and humidity levels stabilized, Claro performed comprehensive treatment of both the living space and crawlspace. The team spray-and-wiped the accessible crawlspace timber, removing visible mold growth from all affected wood surfaces. The living area beam and other contaminated surfaces received thorough treatment.

Post-treatment testing confirmed the intervention worked: total culturable fungi dropped to 150 CFU/m³, with only minimal counts of Aspergillus fumigatus (120 CFU), Chaetomium (13 CFU), and Syncephalastrum (13 CFU). The dangerous mold that had been breaking out across the beam was eliminated.

The large but accessible crawlspace allowed the team to complete the work in a single day, and the homeowner could finally see her beautiful log home beam without the unsightly mold growth that had taken over.

This case demonstrates why addressing moisture sources matters more than rushing into treatment. An incorrectly installed dehumidifier can create mold problems throughout a home—and proper treatment means fixing the source first, then eliminating the contamination.