By W. Douglas Webb
Believe it or not, you often can’t see one of the most important factors in maintaining your building: Moisture Control. Whether it’s a solid, liquid, or gas, excessive moisture in a building can have a large impact on occupant comfort, energy costs, and even a building’s structural integrity. It can also have an impact on the presence of pests—and pest control efforts—that can damage facilities and businesses’ reputations. Moisture control requires significant consideration and planning to ensure it does not cause serious maintenance problems.
1. Become educated on the issue.
Because moisture in its gaseous, or vapor, state is usually not visible and changes relative to air temperature, you might not know how it presents itself or behaves. To put it simply, warmer air can hold more moisture than cooler air. When moisture in the air exceeds the air’s threshold to retain it, it will change to a solid or liquid state. Conversely, when the air is holding less moisture than it can hold, solid and liquid water will evaporate, releasing water vapor into the air.
Your facility likely has many sources of water in the building structure aside from the moisture derived from normal, weather-related humidity. Normal relative humidity in a building structure varies considerably based on the geographic location, situational conditions, and even weather fluctuations throughout each day.
Other sources of moisture in structures are mostly situational, and many may seem insignificant, but the cumulative effects of multiple sources of moisture in a structure can become very costly. Just the moisture expelled into the atmosphere by one person breathing is over one-half gallon per day. When multiplied by 200 people in a building, that is more than 100 gallons of moisture added into the building every day. Obviously, you cannot ask building occupants to stop breathing, nor can all other sources of moisture be controlled, but those that can are certainly worth the effort when the cumulative effects are considered.
2. Assess buildings for any special considerations.
If your building is in a low-lying area or a humid region it may require additional features, such as double entranceways and mechanical dehumidification, to keep outdoor humidity at bay. Identify and repair any other moisture sources, such as roof or plumbing leaks. When water enters a building, it is simply converted from its liquid to its vapor state as it evaporates, or “dries.” Unless it is physically removed, it stays in the building and can turn back to liquid as condensate when conditions are favorable.
Take note of processes that inherently introduce moisture into the air, such as cooking activities in a master kitchen. While this moisture is not always preventable, you can isolate the airspace of a kitchen from the rest of the building with insulation strategies that allow for condensation that will develop if moist, warm air is allowed to reach cooler surfaces.
Landscaping and construction features, such as maturing shrubs and trees that encroach upon a building’s exterior, can direct water into your facility. Construction modifications, additions, or even minor structural failures can also introduce new moisture. With careful planning, regular maintenance and thorough moisture intrusion inspections, you can identify these issues before they become problematic.
3. Understand the impacts for building occupants.
Most facilities address natural fluctuations in moisture with HVAC systems, which can help ensure a comfortable space for occupants by controlling temperature and humidity.
High relative humidity levels can cause people to feel warmer than they would in a less humid space, so it is important to monitor humidity using tools like a recording hygrometer, and make appropriate adjustments in your HVAC usage. If a space is kept too dry, however, this can lead to other discomfort to occupants, even nosebleeds. To promote occupant comfort, the U.S. Environmental Protection Agency (EPA) recommends that indoor air is kept between 30%-50% relative humidity.
There are many other potential problems that can stem from unchecked moisture in facilities. Pest control constitutes one significant moisture-related issue, as even a small amount of moisture can be enough to sustain them. For example, a mouse can obtain enough water to survive from condensation in just a small section of an improperly insulated wall void or air duct. Other pests can survive and repopulate just by feeding on molds and mildew that grow in areas with excessive moisture.
Wood-boring beetles or wood decay fungi can occur in crawlspaces or other poorly ventilated areas that often retain excess moisture. By maintaining normal moisture levels, however, these pests are unlikely to infest.
4. Prevent long-term moisture problems by thinking holistically.
Correcting moisture conditions can be challenging and complex. The costs of inaction can be higher than you might imagine. Over time, moisture can cause human discomfort, pest problems, and even structural issues. Regular inspections, an effective maintenance program, and prompt remediation of moisture issues are best practices that can help keep moisture issues in check and help protect your bottom line.
[Take a quiz on Moisture Control and Pest Management, created by this article’s author and published by Facility Executive in January 2018. Click here for the quiz.]
Webb is technical services manager with Terminix International, and has served the company’s customers across the United States for more than 35 years. He obtained his Master of Science degree in Wood Science and Technology from Mississippi State University, having specialized in Wood-Destroying Insects and Wood Deterioration.