Elastomeric roof coatings can be applied to many commercial and industrial roof types, including bitumen, modified bitumen, Built-Up Roof (BUR), cap sheet, concrete, ethylene propylene diene terpolymer membrane (EPDM), Hypalon, metal, PVS, single-ply, thermoplastic polyolefin (TPO), and transite, as well as newly installed polyurethane foam (PUF) roofs.
One thing is true of all types of roofs and all types of coatings: You’ll know it’s time to apply a coating when the roof shows the earliest signs of aging. At that point, it’s important to act quickly, because the roof may need cleaning or restoration before the coating can be installed. Delay may mean you incur the expense of installing an entirely new roof.
ACRYLIC VERSUS SILICONE
The two major categories of elastomeric coatings function similarly, reflecting solar heat and protecting against water damage over years if not decades. Both are non-toxic and are manufactured according to government rules that regulate the use of volatile organic compounds (“VOC-compliant”).
Both can be applied to multiple roof types, but each was developed for a specific scenario. Acrylic products are designed for metal roofs with positive pitches. By contrast, silicone coatings are appropriate for any flat roof, regardless of construction material, because water tends to pool on those roofs.
PHYSICAL CHARACTERISTICS OF ROOF COATINGS
Elasticity refers not only to the capacity of a material to stretch, but also to its ability to resume its original shape afterwards. Thus, while normally unaffected by temperature changes itself, the coating can change shape as the roof itself expands and contracts.
Tensile strength is the measure of a material’s ability to remain a cohesive whole – in other words, to not break. Many manufacturers list only the tensile strength of a coating when it’s brand new and being tested under controlled conditions in a laboratory. This number has limited utility, since tensile strength of some materials starts to decline almost immediately upon exposure to the elements. An important indicator of a high-quality product and a company that stands behind it is the availability of tensile strength measurements of a coating after it’s been in service for a while. Comparison will quickly reveal that some coatings retain more tensile strength after months of use than others have straight out of their containers. This measurement, therefore, should play an important role in your selection of a coating product.
The permeability factor indicates how much water vapor can pass through a substance. A lower number is desirable, since it represents a higher level of resistance to moisture.
Moisture gain by weight is a related measure, the amount of moisture that is absorbed and retained by a substance, rather than passing through it. Water that soaks into a coating can have an adverse effect on the coating’s adhesion to the roof.
Peel adhesion is the degree to which the coating remains attached to the roofing material under duress.
Tear resistance is a related factor; as its name suggests, it refers to tearing as opposed to breaking.
Reflectivity is the amount of solar heat that “bounces off” a roof coating. A higher number means that a coating will not only lower the interior temperature in your building but also reduce the wear and tear caused by temperature-driven fluctuations in the roofing material.
Where to start? By researching the specifics reported by manufacturers, on product labels or accompanying materials or on company websites. If you have further questions, talk to the roofing professional at Energy Seal.