Structural Drying Basics

Water Extraction Basics

Structural Drying BasicsThe three ways of removing water from a structure are physical extraction, dehumidification and evaporation.


The easiest and quickest way to remove water is physical extraction. The amount of water extracted from the carpet and carpet pad will determine the time it takes for the structure to dry.


The more water that can be extracted, the quicker the structure will dry.


The density, size (oz), thickness of the protective skin of the pad, and the weight, length of fibers, and backing of the carpet will all affect extraction and drying time.


Home Owner Hint

water damage restorationIf you have had water damage affect a carpeted area, always ask your restoration company if they are planning on pulling out the carpet, padding or both.


It is NOT always needed, if any company tells you they are going to “float” your carpet, it’s time to call another company.


Floating carpet is the worst thing that you can do because it may tear or stretch and it will weaken the laminated backing, allowing your carpet to wear faster than it should.


Water damaged carpet should be extracted ONLY with a truck-mounted extraction unit, preferably with a Hydro-X (Also called the Extreme X-Tractor), the highest rated extraction machine currently on the market.


Never allow a company to use an ordinary carpet wand to extract the water from your carpet, it will leave too much water behind!


Types of Dehumidifiers

There are three different types of dehumidifiers used in the restoration industry. They are:


  • refrigerant, whether standard or conventional
  • low-grain refrigerants or LGR’s
  • desiccants.


These three types work differently to perform the same function, that is, remove moisture from air and the surroundings.


Below you will find a quick explanation of how each one works and various uses for it.


Commercial Grade Refrigerant (CGR) Dehumidifiers

Electric refrigerant dehumidification works by passing air over refrigerated coils to condense water vapor. Often at cooler temperatures, refrigerant dehumidification capacity falls off before ideal moisture levels are reached.


There are two types of refrigerant dehumidifiers, standard and conventional. The only difference between the two is that a conventional refrigerant dehumidifier uses a heat pipe or defrost cycle to defer frost from forming on the coils.


CGR dehumidifiers are designed to be moved from job to job in and out of service vehicles. The coil and compressors used are larger than residential units that are only designed for light humidity problems. CGR dehumidifiers are calibrated and designed for high moisture rich environments like flooded structures. CGR’s also use advanced defrost controls to maximize performance.


Low-Grain Refrigerant (LGR) Dehumidifiers

LGR’s are a unique form of residential and commercial grade refrigerant dehumidifiers because they are much more energy efficient and they can pull the grains down much lower. LGR dehumidifiers use a double cooling or enhanced step to lower the moisture laden air temperature once inside the dehumidifier so more condensation can form on the internal cooling coils.


As condensation builds up on the coils, the water droplets drip in to a collector and discharged from the dehumidifier through pumps, or into a floor drain.


LGR units provide the best moisture removal for refrigerant dehumidifiers and produce air that is dryer, heated and with less moisture than commercial grade refrigerant units.


Desiccant Dehumidifiers

Desiccant dehumidifiers work when moist incoming air flows over a wheel filled with a silica gel desiccant.


A desiccant is a material that attracts and holds moisture. This material acts like a sponge drawing moisture from the air (sorption). When the wheel rotates through heated exhaust air, the moisture evaporates (desorption) and is carried outside. Then the cycle repeats.


This process absorbs moisture without ice build-up and is not limited by low temperatures. Desiccants can easily operate below freezing temperatures.

Desiccant dehumidifiers range in size from small electric units to very large diesel fired units. The size is measured in CFM’s or Cubic Feet per Minute, this is the speed in which it will perform an air exchange.



Everything we do on a drying /restoration job is about removing the water and returning the structure and contents to their original dry condition.


Most objects when exposed to water or high levels of humidity will absorb some of the water or moisture, making them damp or wet. By drying the object we are providing an escape for the water molecules from the material and into the surrounding air.


Air also has a level of saturation, the point to where it can’t hold any more moisture. The higher the humidity, the closer the air is to its level of saturation. If the humidity is too high, or has a high vapor pressure, it won’t be able to accept the water molecules from the object to be dried.

water damage restoration


How We Create a Structural Drying (Air Movement) Vortex

Step 1 – Get the facts with your Moisture Meters. Extract as much water as possible (It’s 500 times more efficient to extract than to dry.)
Step 2 – Create a drying plan applying Psychrometrics.
Step 3 – Install the equipment needed to do the job as quickly as possible.
Step 4 – Isolate the area to be dried. Turn on the equipment to create the
drying VORTEX.
Step 5 – Chase the moisture until it’s eliminated / taking and recording Psychrometric readings everyday.


Vortex Drying


Vortex Drying
J & M Restoration in Phoenix, AZ