Stop Counting Equipment—Start Building Drying Plans

Walk into almost any water loss situation and you’ll hear the same questions. “How many dehumidifiers do we need? How many air movers should we install? How long will this take?” These are all very practical questions, but the more important question is: “What is the drying plan?” 

ANSI/IICRC S500 Standard defines successful drying by the restoration professional not by how much equipment is installed or how many days have passed, but by using a performance-based drying approach, where the restorer develops a drying plan that establishes the target conditions, means, and methods to restore the affected materials to their drying objectives. Simply stated, having equipment is not a drying strategy. Having a drying plan is.

One of the biggest industry changes happening today is moving from formula-based equipment calculations to engineering the drying environment. Each structure is unique based on materials, assemblies, environmental conditions, and limitations. So, a flooded basement in January will be much different to dry than a commercial office space flooded in July. Furthermore, the method to dry hardwood flooring is completely different than painted drywall or concrete. The successful restorer recognizes that a drying plan must address these variances before any equipment is deployed.

ANSI/IICRC S500 defines a drying plan as a plan that establishes the target ranges, means, and methods for controlling humidity, temperature, and airflow to accomplish the drying objective while addressing project limitations, complexities, complications, and conflicts. By simply defining that a drying plan is about “target ranges, means, and methods”, the entire mindset of the restorer should change. Instead of asking, “how much equipment do I need to install?” The restorer should be asking, “what environment do I need to create to dry these materials?”

Creating an effective drying plan does not start when the first truck arrives on site. Rather it starts at the pre-restoration evaluation. ANSI/IICRC S500 defines the pre-restoration evaluation as the investigation by the restorer to establish recommended corrective actions based on the information and evidence gathered by the restorer during the inspection process and the conclusions and findings from the preliminary determination. Information obtained from the pre-restoration evaluation will support the development of the restoration work plan, drying plan, safety and health plan, and determine whether the project requires the services of subject matter experts to successfully clean, dry, and restore the structure, building systems, and contents to an acceptable drying objective.

This concept is foundational to the entire restoration process but is frequently overlooked. Before a single piece of drying equipment is installed, the restorer should have already completed a comprehensive evaluation of the loss. This pre-restoration evaluation identifies the source and classification of water, moisture migration, materials and assemblies impacted, occupancy conditions, project limitations, complexities, and conflicts, along with an assessment of any health and safety concerns. Or if specialized cleaning and drying methods are required, or if subject matter experts or specialized equipment are needed to successfully complete the job. In other words, the pre-restoration evaluation answers the “what,” “why,” and “how” to approach the restoration and sets the stage for developing the drying plan.

With the pre-restoration evaluation guiding the development of the drying plan, the next step is to establish drying goals. Before any equipment is installed, the restorer should establish target or acceptable moisture conditions for salvageable materials. Drying goals can be based on comparisons to unaffected materials within the structure, manufacturer guidelines, historical data, or other acceptable references. Once these drying goals are established, a restorer can then begin engineering the drying environment. 

The key to rapid and effective drying is to manipulate temperature, humidity, airflow, vapor pressure differential, and interstitial airflow, as a combined system (not as separate components) to influence and control moisture migration from the structure and materials.

The S500 recommends that every drying plan identify drying environment conditions that achieve the drying objective. The drying environment can include humidity levels, atmospheric and material temperatures, air velocity, vapor pressure differential, and other factors influencing the evaporation process. With these conditions identified, the restorer can then begin to select the type of drying system that will be used to influence these conditions.

S500 further recommends that the drying plan identify the target drying conditions and the specific means used to influence the targeted drying conditions – such as a closed, open, or combination drying system. The selection of a closed, open, or combination drying system should be intentional, and be based on building characteristics, weather, occupancy demands, and drying objectives. The drying plan should also identify how the restorer will manipulate the building environment (containment, dehumidification, supplemental heat, air filtration, HVAC modifications, and airflow management) to influence the drying process. The initial equipment selection should be based on the on-site conditions but should not remain static or rely strictly on the equipment selected at the project’s inception (due to prevailing weather, seasonal conditions, building envelopes, room configurations, occupancy, construction densities, and other factors influencing the evaporation process). The S500 recommends continuous equipment adjustments based on documented progress and changing field conditions rather than maintaining equipment as initially staged.

An effective drying plan will identify the materials, assemblies, contents, and building systems being dried. Each component within the affected area does not always require additional drying attention. Likewise, not every assembly needs to be approached in the same way. In addition to identifying the target moisture conditions for materials, the drying plan should define the intention for specific assemblies, materials, and contents. Particular attention should be given to Class 4 materials and those with low permeance – such as dense or narrow-pored woods, heavy woods, plaster, concrete, masonry, and multi-layered assemblies. Class 4 materials may require extended drying times, supplemental heat, specialized drying systems, localized environmental control, and enhanced monitoring to meet the established drying goals.

Another commonly overlooked factor in the drying plan is the buildings HVAC system. In some cases, it can be utilized to support drying objectives, or it may need to be shut down entirely to prevent contaminant migration. Whether the building HVAC system is utilized or isolated should be addressed in the drying plan, rather than left to the discretion of the restorer on the job.

Every drying plan should identify concerns for potential secondary damage. Wood flooring can distort if dried to rapidly, hardwood finishes can blister if exposed to extreme temperatures, plaster can weaken if not dried correctly, and high relative humidity can promote biological growth. Excessive air movement can mobilize contaminants if proper containment strategies are not utilized. Therefore, environmental conditions influencing these concerns should be addressed in the drying plan to ensure they do not become a factor, before the drying process begins. Understanding these potential issues allows the restorer to monitor the job and adjust the environment accordingly, without compromising the drying progress.

Ultimately, the effectiveness of the drying plan will be determined by monitoring progress throughout the project. Psychrometric readings, moisture content, surface temperatures, vapor pressure differential, and material trends should be reviewed and trends documented to determine if the plan is working. If progress has stalled or the environment is out of control, the drying plan should be re-evaluated rather than waiting for time to elapse. The S500 encourages the restorer to measure and confirm that the system is working and to make modifications based on the evidence.

Restoration projects with the most successful outcomes tend to be those where the restorer takes the time to understand moisture and environmental control. A drying plan helps to transform restoration from a “guesstimation” to an engineered science. It is a document used by technicians, project managers, insurers, and consulting firms to confirm that goals are understood, the methods to meet these goals are recognized, and an appropriate level of success can be measured. As a result, clients today are demanding more than just equipment, they want confidence and assurance. A drying plan supports these expectations by showing that a restorer is capable not only of taking care of their structure but doing so in a controlled and documented manner that ensures drying is complete, the environment is stable, and no further damage will occur during the drying process.

So, the next time you walk into a water loss and hear someone ask, “How many dehumidifiers do we need?” or, “How many air movers should we install?” Perhaps the better question would be, “What is our drying plan?” The ANSI/IICRC S500 has shifted the focus from equipment deployment to environmental control, recognizing that successful structural drying is achieved by establishing, managing, and verifying the conditions necessary to reach clearly defined drying goals. The drying plan is where those decisions come together. It transforms the findings of the pre-restoration evaluation into a deliberate, measurable strategy that guides every stage of the drying process—from defining drying goals and engineering the drying environment to monitoring progress, adjusting equipment, and ultimately verifying that the structure has returned to an acceptable dry condition. A well-developed drying plan is far more than a project document; it is the technical blueprint that transforms restoration from a reactive response into a disciplined, science-based process.

Disclosure: Parts of this article were generated using ChatGPT based on prompts provided by the author. The full draft was reviewed, fact-checked, and revised by human editors prior to publication.