Types of Cold Applied Roof Coatings

The term “cold applied roofing system” is traditionally taken to mean a built-up roofing system assembled using solvent-borne bituminous (liquid) adhesives and multiple plies of reinforcement. There are, however, several other types of roof membrane systems that do not require heating are now on the market (single-ply, spray foam, etc.) so it is necessary to be more specific. RCMA members manufacture the following specific types of cold-applied roofing.

Product Advantages

The primary advantages of roof coatings and cements are their economical, proven performance life, and ease of use. Roof coatings and cements are generally one-component products that can be applied directly from the container. Today’s coating and cements are versatile and applicator friendly. Non-flammable products are also available.

Cold-Process Built-Up Roofing System

This type of roof can now be constructed a variety of ways. The predominant technique is to use heavyweight asphalt coating fiberglass “base” sheets and adhere them with solvent-borne asphalt adhesives in multiple plies. The first sheet is usually mechanically attached to the substrate (insulation) and subsequent plies (usually three or four total) are embedded in an application of adhesive at a rate typically between 1.5 and 2.5 gallons per square (100sq. ft.) The membrane is then covered with an aggregate surface or roof coating.

Cold process built-up roofing systems now exist that use coated or uncoated polyester reinforcements, or composite (polyester/fiberglass) reinforcements, in conjunction with either solvent-borne or waterborne adhesives. The combination of reinforcement and adhesive is typically proprietary to the system provider and compatibility should be verified with the manufacturer.

Cold process built-up roofing systems are available as complete systems or as repair system for new construction or re-roofing, and they are available in a variety of constructions to meet all budgets. Roof rated by Underwriters Laboratories (UL) and Factory Mutual (FM) are now available.

Adhesive Application of Modified Bitumen

Membranes Modified Bitumen roofing is similar to built-up roofing in that it employs reinforcing materials coated with bitumen. The primary difference is the use of “modification” or addition of polymers to the bitumen to achieve improved characteristics. Like built-up roofing, modified bitumen roofs were typically installed using moppings of hot asphalt. An alternate approach for some types of modified bitumen was to use a propane torch to melt the back of the sheet, creating a molten adhesive in which the roll could be embedded.

Perhaps the fastest growing segment of cold-process roofing is the application of modified bitumen roofing in bituminous cold-process adhesives. For obvious safety reasons, use of cold-applied roofing has provided an attractive alternative to the use of hot asphalt or open flame. These roofs typically have a mechanically attached base sheet, and one or two plies of modified bitumen membrane installed in bituminous adhesives.

Liquid-Applied Monolithic Membrane Systems

A third type of cold-applied roof now exists which blurs the line between roof coating and roof membrane system. That is the liquid-applied monolithic roof system. Typically made of high-tech polymeric resins such as urethanes, or bitumens which have been modified with polymers such as SEBS, these roof are applied as a liquid and may not rely on reinforcing material, but cure to form a tough, rubber-like membrane. These types of roof are monolithic (no seams) and are typically considered self-flashing.