How Do I Know if the Roof Coating Coverage is Correct?

This is an important question because many roofing provisions and warranty policies require a specific number of dry coat thicknesses to be applied on the structure. To ensure your roofcoating exposure is correct, you will need a wet mil gauge and the volume solids of the roof coating you are using.

What do you mean by wet mil gauge? A wet mil gauge is a tool that is used to define the thickness of the wet coating after it has been applied to the roof surface. It is simply a gauge with points that is pressed into the elastomeric roof varnishes immediately after it has been applied on the roof. The device is then withdrawn vertically with coating stuck to some of the points. You want to note the deepest points having coating on it and the next deepest points that do not have coating on it. The true wet film thickness is somewhere between the two readings. Once you have determined your wet mil thickness, you then need to know the percent solids by volume in the coating. The wet film thickness is then multiplied by the percent of volume items to give you your dry film width.

Although it is a relatively simple procedure to figure out the actual dry film wideness of your roofing structure, there are three important factors to consider having the proper roof coating coverage for your building or house. First, is the measurement of the wet film thickness immediately after the application of the roof varnishes to ensure the coating does not evaporate or dry, as this would give you wrong measurements. Second, is the wind loss factor when applying roof coatings. A 20 mph winds may result into a loss of 20- 30% of the coating essential. Last, is the need for extra material that could be from 3- 10% of the overall amount of coating required for the structure to account for thickness variations in the applications as well as for the miscellaneous coating remains in the lines and in the vessels.

Achieving the proper roof coating coverage is a very significant step in applying a roof coating process to any building.