Past water extraction procedures involved removing water from the carpet, replacing the pad, and drying and re-installing the carpeting. Today, restoration companies use the techniques of psychrometry (the science of drying) and state-of-the-art equipment that can sharply reduce the severity of claims. Psychrometric techniques require continual measurement of the relationship between temperature and relative humidity, and a reading of the air's moisture content, or GPP (grains of moisture per pound of air). Technological devices, such as thermo-hygrometers, assess the temperature and relative humidity of the air, both indoors and outdoors.

The amount of humidity in the air plays a role in how the area should be dried. For example, low-humidity, outside air sometimes can be used to dehumidify inside air, simply by opening doors and windows. Moisture sensors allow restoration experts to discern whether materials are wet or dry; while penetrating or non-penetrating moisture meters determine the extent of wetness retained in building materials.

The restoration exercise involves four major steps:

oEvaluating the damage and moisture content of the air and materials

oDiagnosing the quality of the water causing the damage, whether materials can be restored or must be replaced, any special precautions that should be taken to protect the crew, and the speed of drying that can be expected

oOutlining restoration goals and methods — what drying system and equipment will be used, and the plan for daily monitoring of progress

oDetermining that the structure, materials, and environment have been restored to their pre-loss condition

The initial evaluation includes determining the source of the water causing the damage: fire department water, property owner's negligence, faulty plumbing, or defective appliances. Disaster restoration experts determine which specific areas are wet. Just because carpet feels dry upon touch, it does not mean the job is complete. Carpets dry faster than most materials. Restorative drying professionals use special tools to attack wet areas and to monitor drying progress.

Damage then is evaluated, paying specific attention to possible carpet delamination (separation of primary and secondary backings), carpet or floor stains, and other damage. Moisture detection equipment measures the wetness of contents and determines the GPP. Relative humidity will hold; the temperature and airflow also are important for the drying process.

In the diagnosis phase, the type of water must be determined, depending on the source: “clear” water; “gray” water, with chemical, biological, or physical contamination, and posing a health threat; and “black” water that is grossly unsanitary, with serious health implications, requiring that restoration crew use personal protective equipment. The type of the water causing the damage determines whether contents can be restored or must be replaced.

How slowly or quickly the moisture evaporates depends on which materials and how large an area are affected. Generally, the more widespread the water damage, the faster the evaporation. Then comes the water removal, using appropriate dehumidification equipment and methods. IICRC guidelines provide the formulae for deciding how many air-mover units are needed and how much refrigerant or desiccant is necessary, based on the cubic footage of the water-affected room and the speed of evaporation that is expected. These indicate how much heat is required to speed up evaporation without damaging materials or making occupants uncomfortable. The guidelines also address whether open drying, bringing in outside warm, dry air, is an option, taking into account building security, heat loss, and changing weather, among other concerns.

Daily monitoring of moisture content and the drying progress is crucial, allowing restoration professionals to record changes in GPP and moisture content in materials, and adjust equipment as necessary. Many adjusters and restoration companies take readings at the start and at the end of the process. If they never look at moisture content in between those times, however, they only know what the air is doing. They do not know whether the contents are releasing moisture into the air, maintaining wet environments. The crew still may need to dry the air, taking more grains of moisture from each pound of air. Other problems may include insufficient extraction of moisture from content materials, incorrect use of equipment, continued moisture saturation, and possible rises in humidity when equipment is removed.

The most important aspect of restoration drying is frequent monitoring of conditions. It ensures cost-effective drying, so that restoration and resulting claim handling can move efficiently from evaluation to completion — from wet to truly dry.

Pete Duncanson is director of training, disaster restoration, at ServiceMaster Clean.