A Case Study: Flooded Basement at Multi-Family Project Fully Dried and Mold-Free Through COMMP®

Sometimes, mother nature doesn’t let up – and that’s exactly what happened to a 298-unit multi-family property in Rockville, MD during construction in the summer of 2025.

Heavy rainstorms caused water to accumulate in the lower levels of one building, creating conditions that began to delay construction and led to high humidity concerns on the lower 2 levels of the building. 

As the proactive partner for mold prevention on site, Clearity Environmental stepped in to work alongside the construction team to dry out the affected areas fast, keep the project moving on track, and ensure a mold-free build.

The Issue

Several things were working against this team during construction; It was the “perfect storm”, as some might call it.

Initially, there was a leak in the basement storage room of one of the 4 buildings, unbeknownst to the crew, that essentially flooded the basement with two inches of water.

Since the project was taking place during one of the warmest times of the year, it was a damp, humid environment, making it much like a petri-dish.

Even though the on-site team tried to dry out the basement with wet/dry vacs and small fans, the weather made it nearly impossible to remove all of the moisture. Not to mention, the warmer weather meant windows were often left open by the contractors long after their shifts for the day had ended.

While natural water intrusion is not uncommon, a series of daily thunderstorms made prompt cleanup difficult and increased the risk of secondary moisture-related issues. The sustained weather pattern led to moisture spreading into the hallways of the building.

To add to the issues that were already accumulating, gypcrete pours were scheduled in the building, and rescheduling would have meant a 2 month delay. The gypcrete pour added even more moisture to the air, affecting the drywall in the lower levels, and eventually leading to the contractor having to cut out the majority of the drywall from the lower levels.

Unfortunately, visible mold was also found in the gypcrete, and required treatment before any drywall could be reinstalled.

The team desperately needed a solution for the humidity, water, and their project timeline and budget.

The Solution

This project was part of Clearity’s Control of Moisture and Mold Prevention (COMMP®) program, a proactive approach to prevent mold during construction and deliver a certified mold-free building by project completion.

Clearity identified elevated moisture levels in drywall throughout every unit on the lower 2 levels of the affected building, along with interior humidity levels exceeding 90%. When humidity levels get this high, the chances for condensation to form overnight grows, which can quickly result in explosive, wide-spread mold growth. 

At this stage, the concern was not visible mold, but the environmental conditions that allow mold to develop. Addressing those conditions early and deliberately is a cornerstone of the COMMP approach and was critical to preventing a far more disruptive outcome later in the project.

Initial drying efforts using fans and small dehumidifiers were insufficient given the volume of moisture present. Working as an extension of the construction team. Clearity guided the development and execution of a targeted moisture management plan that became part of the overall job workflow. 

This targeted plan incorporated procedures that went beyond the overall written COMMP program that had been developed for the contractor on this project. Specifically, Clearity recommended escalating the response to large, industrial trailer-mounted desiccant dehumidifiers to quickly and effectively eliminate the substantial moisture concern before it might result in mold throughout the building.

These desiccant dehumidifier units, being as big as they are, were delivered to the site on trailers and were deployed to aggressively (and quickly) pull warm, moisture-laden air from the building and introduce desert-like hot, dry air into the building to hasten the drying process.

This approach allowed wet building materials on the lower two levels to be dried quickly and thoroughly, stopping mold before it could develop. While drying the lower levels, gypcrete pours continued on upper levels of the building, raising the same moisture concerns that prompted the use of desiccant dehumidifiers on the floors below. After drying the lower 2 levels of the building, the dehumidifiers were moved to address elevated moisture content in building materials on the two upper levels of the same building. 

As part of the COMMP® program, Clearity coordinated:

• Ongoing inspection of affected areas and tracking moisture levels to understand the scope of the issue.

• Keeping clear on-site documentation, including inspection forms and water intrusion response forms.

• Managing mold response and tracking water incidents to make sure issues were addressed quickly and consistently.

In addition to moisture prevention, Clearity also supported keeping the project in compliance by performing required radon testing in accordance with City of Rockville and Montgomery County regulations. 

Once construction was fully completed, Clearity set up radon monitoring across all four buildings for a three-day testing period and submitted samples for analysis to ensure the project met local requirements prior to occupancy.

A caucasian man and a caucasian woman near a gray chain link fence talking on a construction site.

The Outcome

While the client was initially concerned about the cost of the large desiccant dehumidifiers, they were very pleased with the results once the work was completed. The dehumidifiers successfully and quickly dried the lower two levels of the building, and by moving them to the upper levels. Clearity took a proactive step that gave the client extra peace of mind and ensured comprehensive protection against any hidden moisture.

The project did create some obvious frustration due to the unexpected disruption in the construction schedule. However, level-headed communication and clear planning from Clearity allowed the team to address issues proactively without derailing progress.

This approach avoided what most assuredly would have been a far more extensive mold remediation effort, requiring removal of all drywall in the building, that could have added significant time and cost to the project. 

Thankfully, early intervention and an aggressive response kept the project on schedule, minimized disruption, and gave the client confidence that the building would remain mold-free.

By anticipating problems before they escalated, Clearity helped the team save both time and money while delivering a healthy, compliant, and certified mold-free building, receiving their final certification in January of 2026.

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Keep Your Project On Schedule and Your Team Confident

With Clearity as an embedded partner, your team is able to address potential issues quickly, prevent costly remediation, and keep the project moving on schedule. Our COMMP Program can help you avoid unexpected delays, protect your work, and deliver a compliant, certified mold-free building your team and clients can trust.

Don’t let hidden moisture or mold derail your project. Schedule a consultation today at 941.866.2355.