Heat Drying Structures
“The Truth about Heat Drying of Structures”
Heat is used world wide for evaporating water, heating the water gives the water energy to break the bond from liquid to vapor (evaporate). Increasing the air movement across the wet surface sweeps away the water vapor molecules and causes more water molecules to break the bond from water to water vapor. Heat and air movement are synergistic.
Examples : Clothes dryers - hair dryer – dish washer dry cycle – bathroom hand dryers
Warm air is capable of sharing more space with (holding*) water vapor than cold air. If the outside air temperature is 75°F and the relative humidity is 45 percent, that same air inside your 130°F home will have a 9 percent relative humidity. That’s (thirsty*) dry air.
Air is technically not thirsty and air does not hold water. Water vapor and air do exist together. The term thirsty describes the availability for vapor molecules within the air space. Air does not actually bond with water vapor therefore air does not hold water. Cold air is denser than warm air. Therefore there is less available space for water vapor. Warm air is less dense, hence more available space for water vapor.
Although it is important for airspace to have availability (room) for water vapor, you need heat to create evaporation. Dry air does not cause evaporation, adding heat (energy) to the water does!
Heat can penetrate non-permeable coatings & materials.
Most cases you do not need to vent a wall cavity or remove base board, etc… because heat penetrates the materials to heat the water beyond the surface of the material. Water vapor is able to penetrate plaster and wood readily. This allows for water vapor to leave these materials readily once evaporated. Movement of air through the building structure is done with positive pressure. This forces the air out of wall cavities, etc… in most situations. Duration of time material is wet and pre-existing issues are less of concern when heat drying.
Heat that is controlled does not damage or dry the structure too fast.
Heat properly controlled is not damaging to the structure. Water is dense and takes time to absorb the heat, thus eliminating drying too fast when under professional supervision. Thermostatically controlling the heat keeps the heat in the proper range for optimum drying without creating unnecessary secondary damage. Complete Drying usually occurs within 48 hours.
Fresh heated air that is circulated in the structure and then vented out prior to cooling (open drying system) does not cause condensation problems in the structure. Therefore no dehumidifiers are necessary. Heat eliminates or reduces odors associated with water losses.
Dehumidifiers are normally necessary in a closed drying system. Closed drying circulates air within the drying chamber increasing Relative Humidity (RH) creating a need for water vapor removal using dehumidifiers. Whereas air exchange in heat drying continuously removes the old air and replaces with fresh new heated air never allowing an increase in RH while maintaining optimum drying conditions from start to finish.
Heat dries faster taking away the time & conditions needed for mold to grow.
Evaporation is the process in which a liquid turns to a gas by increased molecular energy.
Heat deters and can even kill mold as it dries the structure.
Mold requires nutrients, water, oxygen and favorable temperatures to grow. Nutrients for mold are present in dead organic material such as wood, paper or fabrics; mold can also derive nutrients from some synthetic products such as paints and adhesives. Mold requires moisture, although some mold species can obtain that moisture from moist air when the relative humidity is above 70 per cent. Many molds thrive at normal indoor temperatures; few if any molds are able to grow below 40 F or above 100 F. Outside this range molds may remain dormant or inactive; they may begin to grow again when the temperature is more favorable. Temperatures well above 100 F will kill mold and mold spores, but the exact temperature required to kill specific species is not well established. Dr. Nathan Yost, MD. Building Sciences Corporation
Heat eliminates the need for antimicrobial applications on most jobs.
The Louis Pasteur method of heating liquids for the purpose of destroying viruses and harmful organisms such as bacteria, protozoa, molds, and yeasts. Indirect benefit of heat drying is a healthier environment without the need for toxic chemicals.
Heat can dry structure without removing baseboard, tile cove base, cabinets, etc…
Heat penetrates deep into and through building materials drying areas that are not accessible. Intelligent venting, when necessary, requires little to no repair. Certain materials should be removed due to irreversible damage when wet. Example: MDF or compressed paper baseboard. This does not mean they should necessarily be removed during the drying process.
Carpet can be dried without manipulation in many cases.
Carpet backing loses strength when wet. Manipulating the carpet, not water, is what damages the carpet. Main damage occurs when detaching carpet from tack-strip. Carpets are cleaned using water all the time and no damage occurs. Time wet (flooded) can create issues with stain resist coatings and warranties. Most cases carpet & padding can be dried in place causing no additional damage.
Heat drying reduces A.L.E.
Shorter drying time, less invasive, allows immediate move-back, less inconvenience to homeowner and less cost to the insurance carrier