The appropriate number of air movers and dehumidifiers that are needed to dry a building is dependent on cubic foot, square foot, amount of wet walls & amount of wet contents. Some jobs may not require dehumidification, however air movers alone only serve to move moisture from the water soaked material to the air space. If the moisture is not taken out of the air space, drying slows down and secondary moisture damage to other surfaces and contents can result. Also the length of time that the equipment is needed can be based upon achieving the desired relative humidity (RH) and moisture content (MC) in structural materials. The rate of reduction in (RH) and (MC) is the indicator of whether or not there is enough equipment or if the equipment is working properly.
The relative humidity (RH) and the moisture content (MC) of structural materials in the work environment need to be monitored and recorded on a daily basis. If the RH or MC is not dropping, additional air movers and/or dehumidifiers may be required. There are many variables in controlling moisture that need to be considered, such as elevated outside RH that can cause slower drying.@70°F and under 20% moisture content in most structural materials. Below 20% MC, the materials generally will no longer support mold growth. Some structural materials, such as hard wood flooring require an MC of 8-12% in order to prevent or correct damage.