Rainbow International® of Harlingen

You probably have heard about or read about Top Down Drying. You might have even had restoration companies that have used the process. If so, hopefully the job was processed quicker and at a lower cost over some of the more conventional ways of processing water losses.

"Top down drying" is a poor term for describing the process; the term came about as a result of a heavy emphasis put on drying carpet and cushion in place. Even though in some cases this process does allow carpet and cushion to stay in place, the real strength and emphasis of this process is drying the structure quickly. Therefore, a better term for this process is "rapid structural drying." In the past, most processes for drying put the primary emphasis on drying the floor covering (usually carpet). The cushion was usually removed and air movers would attempt to float the carpet until it was dry. New cushion would then be installed and the carpet re-stretched. This process would typically take 4 to 6 days, requiring a substantial amount of labor cost due to the moving of furniture to remove cushion and carpet, and the reinstallation of the carpet and cushion.

So do carpet and cushion stay in place when using Rapid Structural Drying? The answer is, it depends. It depends on the type of water loss. Cushion is always removed on a Category 2 loss and carpet and cushion are always removed on a category 3 loss. The homeowner or the adjuster may request that cushion be removed. Carpet and cushion may be installed over strip wood floor, which would require carpet and cushion to be removed. However in many situations the carpet and cushion dry out very fast due to their porosity and can remain in place. This lowers the cost of the claim and puts the home back together again quicker. Regardless, the process is designed to dry the structure quickly to eliminate replacement of costly building materials and to reduce the possibility of mold growth.

The process of Rapid Structural Drying revolves around four basic principles. Technicians must maximize all four principles in order to receive the best results.

Principle 1: PHYSICAL REMOVAL OF WATER - removal of water in the liquid state is 500 times more efficient than changing liquid to vapor with air movers and removing the vapor with dehumidification. Specialty tools have been designed to maximize this process such as the Hydro-X Extreme, the Water Claw, or the Flood Pro to remove maximum amount of water out of carpets and cushions. These tools require more time so you should expect a higher line item charge for water extraction. However they can reduce the number of equipment rental days due to their efficiency. In addition to these types of tools, other means of physical removal of water should be taken as required depending on the materials encountered.

Principle 2: EVAPORATION – After as much water as possible has been removed physically, the remaining water must be evaporated using high velocity air. Over the last few years, new types of air movers have been introduced that provide much higher air movement at lower amperage and are specifically designed for Rapid Structural Drying. In the past, air movers were designed to be inserted underneath carpet to allow the carpet to float. Usually one air mover was installed for every 200 to 250 sq. ft of floor space. Today’s air movers sit on top of the floor and face the wall at a 45° angle. These are typically placed at 1 per 10-14 linear feet of wall space. So a 10 x 12 room could have 4 air movers with this system opposed to 2 with the old system. More equipment but faster drying.

Principle 3: DEHUMIDIFICATION - Dehumidifiers are used to balance evaporation. In other words, the moisture being put into the air from the air movers has to be taken out of the air or secondary damage will occur. Without dehumidifiers, hygroscopic materials would absorb moisture out of the air and become damaged, drying would be delayed, and mold growth could occur. Dehumidification might simply be opening windows to allow wet inside air to escape to drier outside air. However if outside air is wetter than inside air, then opening windows only causes more moisture to enter the building, slowing drying even more. Another source of dehumidification is the AC unit although it has limited capability and is usually only efficient for the first 24 hours.

In order to dry structures quickly, restoration companies need dry air. So readings are usually taken once or twice a day to make sure the moisture in the air is being reduced and the proper amount of dehumidification is available.

1. Conventional Refrigerants – These types of dehumidifiers are typically small in size and less efficient, however these are the most common type used, due to the fact that they are less expensive to purchase and should be less expensive to rent. However due to their limited capability of providing dry air, they usually will have to stay on a loss longer increasing the rental fees.
2. Low Grain Refrigerants - Low grain refrigerants are relatively new to our industry and currently only a few models exist. These are larger dehumidifiers that can produce drier air, therefore reducing the time they need to be on the job. Usually, even though the daily rental fee for Low Grain Refrigerants is more than Conventional Refrigerants, the total equipment rental fee is less due to the fact that the LGR’s take less time to dry the structure and fewer are needed.
3. Desiccant – Desiccant dehumidifiers work on the principle of absorption. Similar to the small bags of silica gel you might see in a box when you buy electronics, desiccants produce the driest air but at the highest cost. Desiccant dehumidifiers are often used when drying non-porous materials such as hardwood floor, cabinets, crawl spaces, etc. Large desiccant dehumidifiers are often used on commercial loses where business interruption claims are a concern.

Principle 4: Temperature - Maintaining proper temperature is critical in drying a structure quickly. Warm air holds more moisture the cool air, therefore warm air will increase the rate of evaporation. However there are certain variables to consider. First, refrigerant dehumidifiers are most efficient between 70° & 90°. Second, the equipment itself generates heat which could easily accelerate temperatures to above 90°. Usually within the first 24 to 48 hours, because of the cooling effect of moisture being evaporated from materials, temperatures are easily maintained. After the more porous materials have been dried, the temperature increases and may require equipment to be removed if the temperature cannot be controlled.

More and more companies are adapting rapid structural drying as their preferred process for water mitigation. It requires better-educated technicians, more equipment, and knowledge of how to use the equipment. The net result is structurs that are dried thoroughly and quickly and typically at a lower cost and less inconvenience to the homeowner.