National Coatings Blog

Metal Roof Coating Systems Permit Restoration of Degraded Metal Roofs

Posted by Nicole Gale on Thu, Apr 09, 2015 @ 11:30 AM

028Metal roofing has a reputation of being an extremely durable roofing substrate that has been successfully used on buildings for over 70 years.  Many warehouses, agricultural facilities, food processing, heavy equipment manufacturing, schools and now churches use metal roofing as they provide excellent strength with heavier gauge steel, speedy installation and lower upfront costs over traditional roofing systems. Extending the life of an aged metal roof by using a metal roof coating system is a viable and excellent option as opposed to the other available options of single ply membrane retrofits, roof hugger systems (additional metal layover of the existing metal panel) or the most expensive and disruptive complete removal and re-skin option with all new metal.  Recoating metal roofs can lower roof maintenance and prolong the lifespan of the roof indefinitely, when maintained properly.

As a metal roof ages, the factory applied coating be it galvanized, baked on paint, Kynar or even Anodized protection of the metal panels deteriorate, fasteners break, seams fail, and rust occurs. When the protective coatings that are baked onto the metal panels during manufacturing have worn off, the panels are exposed to environmental elements making them vulnerable to roof failures. The fasteners, which hold the panels together, deteriorate over time and begin failing due to the roof constantly expanding and contracting. This occurs due to normal every day temperature fluctuations and are increased drastically when there are sudden swings in temperature such as a cold fronts, hail impact and rain cooling off of a heated surface in the summer when temperatures of the panel can be in excess of 150+ degrees. These broken fasteners and open seams occur due to stress related exposure and become avenues for water that will surely penetrate the system and enter the building’s interior. Sealants, tapes and caulks that have no UV protection commonly used to waterproof joints and areas between the panels, lose their elongation and recovery abilities, making it difficult to keep up with the buildings‘ constant movement without weakening. Screws and washers become loose and fall off, needing inspection, tightening and replacement. Metal panels can develop rust, needing either full replacement of the panel or the use of a special rust inhibitive primer to restore the panels. The application of rust inhibiting primers are commonly left unprotected and eventually fail. The most common repair material used is asphaltic mastics and should never be used as it is not even meant to be applied directly to a metal panel and must be removed prior to any application of an approved coating for these metal structures.

Recoating a deteriorating metal roof using one of our AcryShield Metal Roof Coating Systems will allow you to solve all the issues mentioned above and leave you with a fully restored, watertight, maintainable and sustainable roofing assembly.

Restoring the roof involves the removal of rusted panels by cutting out the areas that have fully rusted through the panels and replaced with new and like profile to the original so as to promote a solid and continuous seal to the original panel(s). Our low VOC primer, RustShield is then applied to fully combat future rusting of the panels. The AcryShield System offers a choice depending on the severity of degradation to the existing metal. A butyl tape with cloth backing can be applied over all seams and around the base of penetrations, curbs and flashings for a fully sealed and watertight substrate. Screw heads can be encapsulated with either a trowel grade or brush grade AcryFlex mastic and if warranted due to extreme movement/failure a 3-course application of mastic and membrane can also be used to negate future expansion and contraction issues in lieu of the butyl tapes. Next, a base coat with excellent adhesion to metal is installed for exceptional waterproofing. Finally a finish coat containing an industry leading UV protection package is applied. The end result is an easily maintainable and renewable solution that provides long-term performance and low life-cycle cost, along with the added bonus of increased energy efficiency. 

Download our FREE Metal Roof Coating Systems Brochure for additional information or call us at 800-423-9557.

FREE GUIDE: Metal Roof Coating Systems

Tags: Metal Roofing Systems, Metal Roof, Metal Roof Paint, Restore Metal Roof