There is considerable debate over how long it takes to complete a drying job. Some say it always takes three days. Many jobs can be completed in this amount of time. However, some buildings simply take longer than three days to dry. My position is simple: the building is dry when a restoration professional has concluded the building is dry.

When on-site drying methods became popular in the mid 1970s, most companies really offered only a wet carpet service. The word "restoration" was an overstatement of the service provided. The cleaner extracted the water and dried the carpet and cushion.

A simple moisture sensor was considered adequate. If the probe responded, the fabric was still too wet and more drying was required. The only exception was false readings from metallic materials or high concentrations of urine. In most cases, the technician did not concern himself with the remaining moisture.

More than drying wet carpet
By structural materials, we generally mean flooring, sub-flooring, drywall, plaster and framing materials. For this discussion, let's include cabinets, doors and insulation materials in their many variations. Diagnosing, evaluating, monitoring, drying and restoring structural materials and contents represent a much more exciting challenge than handling a wet carpet.

Today, drying a carpet is the least of our professional obligations to our clients. Properly evaluating all water-damaged materials requires specialized tools, common sense and the experience necessary to dry and restore all affected materials. With today's educated consumer, we can even be held liable for an incomplete drying service. Our customers expect a complete drying and restoration job, including structural materials and contents. Today, we know the job isn't complete until all materials are dry.

Humidity, temperature, airflow and time
The four factors that determine how well (and fast) materials become dry are humidity, temperature, airflow and time. If you balance these four factors and consider cost effectiveness and comfort, you can usually minimize the time factor. However, remember that it takes time to dry some structural materials.

You can't assume that "dry air" means "dry materials." Moisture content and humidity are two separate, yet interrelated, issues. Humidity relates only to the condition of the air. Moisture content generally refers to materials, usually expressed as a percentage of moisture content by weight on a quantitative scale or "points" on a relative scale. Just because you have low humidity does not mean that all materials are dry. Likewise, dry materials do not indicate a low humidity. Yet both humidity and moisture in materials have a major impact on one another.

Hygroscopic materials readily take up and absorb water vapor from the air mass as they seek moisture equilibrium with the environment. As the humidity increases, they absorb water vapor; as the humidity decreases, they release water vapor. Most organic materials are hygroscopic to some degree. Drywall, wood, paper, fabrics, some insulation materials and many other construction materials are hygroscopic.

Beware of secondary damage
Most indoor, organic construction materials are designed for a normal humidity condition of 30 percent to 50 percent relative humidity without deformation, delamination or mold damage. A balanced drying system exists when the rate of humidity reduction equals or exceeds the rate of evaporation. However, an inexperienced restoration technician can compound the problem by loading the air with water vapor by using too many airmovers without a corresponding capacity for dehumidification.

Proper humidity reduction is extremely important during restoration. In some cases, these hygroscopic materials absorb water vapor far beyond their design limits, resulting in secondary damage. Common examples of secondary damage include humidity and/or moisture damage to contents like artwork or musical instruments, and structural materials like ceiling tiles, window frames, doors, cabinets and condensation inside walls.

Monitor and record moisture content and humidity
In order to evaluate and control the drying process, and to determine when materials are properly dried, you need to monitor both the condition of the air and the moisture content of affected materials.

A variety of instruments are available for this purpose. These include electronic thermo-hygrometers, and penetrating and non-penetrating moisture meters. Thermo-hygrometers measure both the temperature and relative humidity. From these measurements you can determine the specific humidity of the air with a psychrometric chart. A moisture meter determines moisture content levels. It is used to monitor the rate of drying and to evaluate when affected materials have reached appropriate moisture levels. Both these measurements can be charted daily for additional understanding and as supportive documentation you can provide with your invoice.

Moisture levels in materials should be checked against a dry standard established in another building or against a non-affected area. This gives you a drying goal. In scientific laboratory tests, a control is used to determine the normal. Restorers can establish a guideline by evaluating a material that has not been affected by moisture or humidity. Affected materials can then be compared with the control percentage.

Don't practice old medicine
This restoration industry emerged from carpet cleaners who dried carpet to cleaners who became structural drying specialists. There was a time when humidity and temperature levels were not recorded or documented. You also may not have measured and recorded the moisture content of structural materials. Just because your services were satisfactory to your clients 20 years ago, doesn't mean you can continue to operate that way. As an industry, our responsibilities and exposures are greater than ever.

Today's professional restorer needs to offer better diagnosis and restoration than was available 20 years ago. You now have highly accurate, non-penetrating moisture meters to determine the moisture content of hardwood floors, plywood, particleboard, framing, drywall, plaster and even insulation. You have accurate thermo-hygrometers, which allow you to easily evaluate relative and specific humidity.

We need to monitor and record both humidity and moisture content levels on every job for best results. Many of the materials we deal with are hygroscopic and the more humid the air, the slower these materials release abnormal moisture.

The job isn't done until all the materials are dried. Do not try to determine moisture content by "feel." The only way to determine humidity and moisture content levels is with knowledge and the appropriate instruments. We need to challenge ourselves to learn and use the latest moisture monitoring methods available today.

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