One seldom mentioned benefit of the National Coatings AcryShield product line is that the coating can be easily recoated over itself. Thus, after a decade or more of successful performance, when the coating becomes thin, additional coating millage can be applied without extensive preparation.
Recoating with AcryShield
Before recoating, the coated roof surface must be clean, dry and free of materials that would compromise adhesion. This includes dirt, chalked coating, and other airborne materials that may have accumulated, such as grease, and particulate material from nearby exhausts. Typical cleaning techniques involve the use of pressure washer. Be sure to keep the pressure to a minimum to avoid damaging the underlying roof membrane seams. National Coatings Corporation Cleaner or common TSP may be required to thoroughly clean the originally coated roof.
After the roof is cleaned, there is a simple technique to insure the roof is sufficiently clean for recoating. A piece of masking tape is pressed onto the roof and peeled off. If the tape adheres well, and does not come off easily, the roof is sufficiently clean for recoating. However, if the tape comes off easily, and carries with it chalked coating, dirt, mildew or other particulate, the roof is not clean and must be recleaned.
Cracks and Punctures in the Coating and Underlying Membrane
During the service life of the roof, punctures, holes and cracks may have occurred in the coating. These cracks may extend through the coating and well into the roofing membrane below. The repair will be different depending on the type of roofing membrane.
For asphalt, modified bitumen, and sprayed polyurethane foam (SPF), National Coatings Corporation AcryFlex trowelable sealant can be applied over the crack or hole with a spatula. The sealant should be pressed into the membrane being sure there is no air trapped under the sealant. Large cracks, greater than 1/8" wide should be reinforced with P272 polyester reinforcement scrim. Large holes in SPF roofs may require a foam "plug" to be inserted into the hole. The plug should be imbedded and sealed with AcryFlex sealant.
For thermoplastic and thermoset single plies, a piece of P272 polyester reinforcement 6" larger than the edge of the puncture and pressed into the AcryFlex trowelable sealant. A second application of AcryFlex is applied. After drying, AcryShield coating is applied.
An alternative repair technique for EPDM is to first clean the coated roof, then apply a patch of a non-vulcanized peel-and-stick material. The roof can be coated immediately after applying the patch.
Applying the Coating
The coating can then be applied to the cleaned roof surface. The technique is analogous to applying the original coating. For specifics, follow the Guide Specifications found on the National Coatings Corporation website.
The roof has now been restored to its original condition and original solar reflectance. This process can be repeated many times over, saving the building owner countless thousands of dollars in reroofing expenses. Moreover, since this recoating does not qualify as a recover roof, it is not bound by the code requirements allowing only 2 roofs to be installed before both must be removed due to load constraints. For the contractor there is an immediate economic benefit: it creates an easy opportunity for repeat business with an established client.