Why Wet Surface Temperature is Important when Drying
July 12, 2016
In the new ANSI/IICRC S500-2015 industry standards for professional water damage restoration it says the following:
220.127.116.11.3 Controlling Temperature
Restorers should manage ambient surface temperatures in the drying environment dependent upon the drying system employed.
While the standard and reference guide doesn’t include daily wet surface temperatures in their list of daily project monitoring requirements it is helpful to identify each day the wet surface temperatures of the materials we are trying to dry for it can be an indicator of how quickly it will dry.
The principle is if you provide more energy to a wet surface in the form of heat you can speed up the evaporation process. This is done by raising the vapor pressure of the surface of the wet material and the larger the differential is between the vapor pressure of that wet surface is compared to the vapor pressure of the air next to the wet surface the faster it will dry. This is how your clothes dryer or hair dryer works! This is especially important when drying class 4 water losses that contain low evaporation materials or low evaporation assemblies, like wood flooring, ceramic tile over cement board and wood subfloor, plaster, gypcrete, multiple layers, or when drying other materials that typically release the moisture slowly.
It is not always necessary to pay for portable heating units to use this principle to assist with speeding up evaporation. Just set good containment, depending on the situation, and raise the ambient air temperature in the affected area as much as possible using the structure’s HVAC system and Btu’s of heat from your drying equipment (air movers and dehumidifiers). If something is not drying very quickly than ask for the wet surface temperature reading and moisture content reading and then suggest they tent over that material and exhaust the dehumidifier on that area to raise the temperature. Keep the tented area as small as possible and monitor every 24 hours to judge progress. Remember, we typically get a 10-20 degrees temperature raise from what is going into the dehumidifier to what is coming out of the dehumidifier, so it basically becomes a portable heater as well as a dehumidifier if you can’t get the ambient air warm enough.
Of course, you can get it too hot, especially if there are fragile materials in the affected area like candles, wax, caulking, wine or other materials sensitive to heat. The CodeBlue Recommendation is to keep the ambient air temperatures in the drying chamber less than 100 degrees F and the wet surface temperature less than 120 degrees F. Watch closely for cracking or separation if the temperatures go above 130 degrees F. It is amazing how much quicker wet drywall dries when it is 110 degrees F wet surface temperature vs. 80 degrees F wet surface temperature!
CodeBlue’s goal is to get the policyholder and their family or business back to normal as quickly as possible with the least amount of demolition and disruption. Heating up the affected areas, within our guidelines, and monitoring wet surface temperatures can certainly speed up this process.
Happy Drying! Ed