Brush Up on Your Roof Coatings Terminology


When someone enters the roof coatings industry, it is critical that they learn the jargon and definitions of the profession. These terms will assist a professional looking to learn the business of roof restoration.

Elastomeric Coating

A coating that forms a monolithic, fully adhered, fluid applied roofing membrane. It has elastic properties that allow it to stretch and return to their original shape.



Thickness low enough to allow the material to be pumpable. Base and top coat.


A broader term used to describe the items listed below. Mastic is typically used in waterproofing so it is thicker than a spray grade.


Slightly thicker material that is tough to spray. However, this material is oftentimes extruded through a pump. The material should still be self-leveling. Our most common use is for fasteners on a metal roof. Other uses include seams and penetrations.


A whipped material – thicker than brush grade. This material should not sag and is not self-leveling. Used primarily for penetrations, vertical and horizontal seams.


The thickest of the mastics. Used for seams and penetrations.

Roof Moisture Detection

Core Cut

To cut into a roof down to the deck. Pull the approximately 2” wide sample of the roof to survey to determine if the area is wet. A core cut is only as good as exactly where it is taken.

Tramex Moisture Meter

The Tramex MEP Moisture Encounter Plus is a non-destructive overall building inspection moisture meter which has applications for numerous industries. It has many unique features that make moisture measurement and evaluation fast, precise and versatile. Like a core cut, the handheld moisture meter is only as accurate for areas where you place the meter. Typically a handheld meter only measures 1” deep.

Infrared Scan

Typically performed by a professional with training. An infrared scan uses specialized equipment at dusk to determine if moisture is in the roof system. The basic premise is that water cools at a slower rate than dry material. As the sunlight dissipates the camera will show the difference in temperature. The roof should be marked along with a detail report submitted.

Data Sheet Terminology

Dry Time

Amount of time it takes for the coating to be dry to the touch or walk on.

Cure Time

The amount of time it takes for a solvent to leave the film and for most of the chemical reaction to take place (two-component or moisture cure systems).


The % a coating can be stretched before it breaks.

Tensile Strength

The amount of pressure a coating can withstand before it breaks.

Solids by Volume

The percent of solid material remaining after the coating has completely dried. Measured by applying a coating on a surface; measuring while wet then measuring again 24-48 hours later.

Solids by Weight

A similar test based on weighing the coating when wet and again when dry.


A measurement of how much WATER VAPOR can travel through the coating over a set period of time.

Water Absorption

The percentage of WATER that is absorbed into a coating when it is submerged in water for a set period of time.


The % of the total sun’s rays a coating will reflect.


The % of the sun’s rays that were not reflected, that are released by the coating.

Flash Point

The temperature that a coating or vapor will catch fire when an open flame is introduced at a specific distance.


Volatile Organic Compounds—measured in grams per liter. This figure represents the # of grams of organic compound that are contained within each liter of coating. Volatile = will evaporate. Organic Compound = large class of gaseous, liquid, whose molecules contain carbon: example – mineral spirits.

Film thickness

Dry Film Thickness

(DFT) measured in Mils. The thickness of a coating material or system once cured.


A magnification device that allows us to accurately measure dry mil thickness from samples cut from a roof.

Wet Mil Gauge

A hand-held device used to measure the thickness of the coating on the roof while still wet.

Other Critical Terms

Fluid-Applied System

A complete roof coating system made of specific products for priming, waterproofing, base coating, and top coating. The system is what is warranted by the mfg.


Schematic drawings of specific transition or waterproof areas with step by step instructions of best practices for waterproofing using specific manufactures products.


1 mil = .001 of 1 inch.

Field Adhesion Test

A test performed on a specific roof surface to ensure coating adhesion. See test procedures.

Batch Retain

Typically a pint of material from every batch blended in a coatings plant. These retain are held a minimum of six months.

Waste Factor

The extra coating that needs to be figured into a project to account for over-spray or material left in the drum or pail.

Stretch Factor

The percentage of extra square feet of metal that must be accounted for on a ribbed metal roof when figuring coating material.


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