Airmovers are often treated as the centerpiece of a structural drying setup, and for good reason. Following a water loss, centrifugal airmovers and axial fans are often the most recognizable signs that drying is underway. Positioned throughout rooms, hallways, and entryways, these tools play an important role in increasing evaporation by moving air across wet surfaces and helping carry moisture-laden air away from affected materials.
However, structural drying cannot be completed by airflow alone. Once moisture moves from materials into the air, it must still be controlled and removed. Airmovers help initiate and sustain evaporation, but they do not remove moisture from the drying environment on their own.
Effective drying requires a fully coordinated system: remove standing water, manage humidity, maintain appropriate temperature conditions, and adjust equipment throughout the process.
Before air movement can be effective, the amount of liquid water must be addressed. Extraction is not separate from drying – it’s the first step in controlling moisture. When excess water remains in carpet, pad, and other materials, airmovers are forced to support evaporation that proper extraction should have reduced. Without adequate extraction, the entire drying system starts at a severe disadvantage.
Proper extraction:
For carpet and pad, the full process may include an initial pass with a light wand, followed by deeper extraction using a sealed or weighted tool and system, such as the Dri-Eaz HVE3000 Flood Pumper and Extraction Tool. After water in its liquid state has been removed, air movement will be much more effective during the next phase of the process: evaporation.
The primary job of airmovers is to bring about evaporation by creating consistent airflow across wet materials. They help replace the thin layer of moisture-laden air that forms at the surface of wet materials with drier air from the surrounding environment.
In structural drying, this surface layer is referred to as the boundary layer. As water evaporates from carpet, drywall, wood flooring, and other materials, humidity increases at the surface. If humid air stays at the surface, evaporation slows. Airmovers help disrupt the boundary layer and enable more efficient drying.
Airflow also creates a blending effect by circulating air throughout the affected area. It moves warmer, drier air from dehumidifiers toward wet materials, while carrying moist air away from surfaces so it can be removed from the structure by dehumidifiers.
But effective airflow is not simply a matter of adding more equipment. Airmover performance depends on:
Velocity – how quickly air moves across wet surfaces.
Volume – how much air moves throughout the affected area.
Static pressure – how well airflow overcomes resistance from materials and obstructions.
Placement – whether the right type of equipment is directed toward the affected materials.
The value of airflow also changes as materials dry. Higher airflow is often most beneficial early in the process, when more surface moisture is present. When much of that surface moisture has evaporated, additional airflow may yield diminishing returns – especially if temperature and humidity aren’t controlled.
A balanced drying system depends on the relationship between humidity, airflow, and temperature – commonly known as the “drying pie.” Airflow helps evaporate moisture from wet surfaces; dehumidification removes it from the air; and temperature influences how readily moisture evaporates and how much moisture the air can hold.
When these factors are balanced, drying happens. When they are not balanced, drying efficiency drops. For example, adding more airmovers may help with evaporation temporarily – but if dehumidification is not keeping up, the air can’t take on additional moisture, and drying slows. If temperatures are too low, evaporation may slow – even with airmovers and dehumidifiers in place.
Drying conditions change constantly throughout each project, so be sure to evaluate regularly. Moisture levels, temperature, relative humidity, grains per pound, dew point, and surface temperature all help indicate whether the drying system is working well.
This is where the science of drying – psychrometry – becomes essential. By understanding how temperature and humidity interact, you can more accurately determine whether the environment and setup continue to boost evaporation and moisture removal, or if adjustments are needed. For example:
If humidity is rising, dehumidification may be improved.
If material temperatures are low, evaporation may slow.
If surface temperatures approach the dew point, there may be a risk of condensation.
Low-grain refrigerant (LGR) dehumidifiers are especially useful in structural drying because they are designed to remove moisture efficiently under a wide range of drying conditions. When paired with properly placed airmovers, LGR dehumidifiers help maintain the low-humidity environment needed to sustain evaporation.
Remote monitoring can also aid in better drying decisions and ensure thorough results. Dri-Eaz Command Hub dehumidifiers, used with the Dri-Eaz Command Center Pro mobile app, allow monitoring from anywhere. Being able to access data remotely makes it easier to identify changes in conditions, confirm equipment performance, and make timely adjustments before drying slows down and secondary damage occurs.
Applied Structural Drying (ASD) training provides a structured approach for interpreting psychrometric readings and data, along with practical guidance for making drying setup changes in the field.
Effective structural drying is all about employing and managing an entire system to move moisture from materials into the air and out of a structure. Airflow plays a key role – but it’s not the whole story. It is crucial to have a solid understanding of how the three key components of the drying pie – humidity, airflow, and temperature – contribute, as well as how to leverage extraction and monitoring to maximize results.
Check out the course schedule at Restoration Sciences Academy (RSA) to explore upcoming courses to help build your drying knowledge. RSA provides hands-on, in-person training, including the ASD course, at campuses in both Burlington, WA and Nashville, TN, as well as multiple online options.