National Coatings Blog

Roof Coating Membranes vs Single-Plies/Installing a Second Roof

Posted by Nicole Gale on Wed, Aug 21, 2013 @ 08:00 AM

Benefits of Roof Coating Membranes vs 
Single-Plies/Installing a Second Roof to Your Existing Roof

roof coating membranes

Building codes usually allow you to add a second roof to your building if the first roof is failing. Anything after the second roof, you typically need to choose between a roof tear-off/new installation or a roof coating membrane system. A roof coating membrane system is the superior choice for several reasons over a tear-off/new roof but what if your building currently has only one roof, what is the better option, apply a new single-ply membrane to the existing roof or apply a roof coating membrane system to the existing roof? The answer once again is apply a roof coating membrane system. Let us explain.

Roof coating membranes are typically spray applied. This allows them to create a monolithic and seamless membrane which is custom tailored to fit your roofs exact needs. If your roof needs additional slope to eliminate drainage issues, roof coating membrane systems (particularly the AcryShield SPF Roofing Systemallow you to build in that slope to redirect the water towards a drain. If your roof experiences a lot of ponded water issues, AcryShield coatings are ideal because they are formulated for resistance to ponded water and protection against biological attach, such as algae and mold. If your roof has skylights, pipes, or equipment on the roof (as most do), roof coatings are sprayed directly on the areas where those items meet the roof, creating a seamless, watertight seal in those areas. 

Single-Plies are not spray applied; therefore, they cannot be custom installed and tailored to meet the particular issues each individual roof has. Single-plies are prefabricated sheets of material that are brought up on the roof and cut and trimmed to fit the size and shape of the roof. It cannot bend, mold and form fit like a liquid coating is able to. A single-ply can not wrap itself around items on a roof like the coating can - it needs to be cut, shaped and placed on the pipe or foot of equipment and then seam-welded, nailed or drilled. Then it needs to be filled/puttied with a sealer so leaks do not occur. The sealant does not have the same adhesion capabilities to the single-ply as a coating has to itself. This makes the single-ply more likely to tear away from the sealant and leak in the future. 

A coating is similar to a paint in that when it is sprayed, it fills small cracks and voids in the roof to create a solid, smooth surface. The coating then dries and hardens together to become a monolithic membrane. Our coatings contain high solids and premium ingredients making them high performing and flexible so they can move with the expansion and contraction of the roof. 

Single-Plies may be installed to the roof deck or substrate using mechanical fasteners, seam welding, adhesives and nailing. They are not 100% adhered to the existing roof membrane like a coating is because they are basically placed on top of the roof membrane or deck and fastened to it. They do not have the ability to be as watertight as a coating system does because they do not fill all the cracks and voids. Single-Plies have the ability to stretch a little but often times become brittle and crack over time due to plasticizer migration. This causes the single-ply to become less flexible leading to potential leaks when the roof experiences movement.  

The important differences of a liquid applied system (roof coating membrane) versus a prefabricated system (single-plies) lead us to believe there is no better choice when faced with restoring your roof other than a roof coating membrane system. The ability to custom install your roof to fit your buildings' exact needs are unparalleled. If you are looking for a watertight solution with excellent adhesion to your existing roof membrane, choose from one our AcryShield Roof Managment Systems (ARM)AcryShield SPF Roofing Systems, or AcryPly Roofing Systems

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