Steel Roofing Fade and Chalk
14 years ago Hansen Pole Buildings provided a post frame building kit package to a client in South Carolina. Included with this investment was steel roofing and siding to be provided by Fabral with 20 year warranty paint. Colors were Evergreen roofing and trim and Tan siding.
We actually provided Fabral’s MP (also known as Multipurpose) panels with a 25-year limited paint warranty and a 10-year warranty against fade and chalk. Our client actually got a greater paint warranty than what he had bargained for.
Fast forwarding to current times and our client emails, “What type of warranty comes with the Tin on the roof and sides. I bought a building several years ago with a Green roof, and now the roof is turning white and chalky.”
Our client provided the photo above (please try to ignore random screw pattern and totally missing screws) as proof of his roof’s current condition).
Strangely paint quality is one thing rarely mentioned by potential clients when considering a new steel covered building – when it should be a most important one. Paint on steel roofing and siding is not just for decoration. In addition to providing color, paint finish also protects panels from corrosion, temperature, moisture and other detrimental environmental elements. Fading is the most common source of color change over time and happens when environmental elements deteriorate paint’s pigments (granular particles giving paint its color). This deterioration also reduces paint’s effectiveness in protecting steel panels.
I have opined about paint fade in an earlier article: https://www.hansenpolebuildings.com/2014/04/paint-fade/.
But what about chalking?
Also referred to as “powdering”, chalking happens when resin (binder) of a paint system is compromised. Resin is the substance holding paint pigment together. It also ensures color is evenly distributed and provides glossiness, durability and flexibility. In addition, resin has a very important job – adhering pigment to the steel surface it is applied to and protecting the finish against damage.
When paint finish surface resin deteriorates, most often as a result of exposure to ultraviolet (UV) rays, embedded pigment particles lose their adhesion to paint film (resulting in color fading) and resin particles take on a white (chalky) appearance, easily wiped off (this chalk can be removed: https://www.hansenpolebuildings.com/2017/08/removing-chalky-residue-steel-panels/). In addition, chalking can erode the film resulting in a loss of substrate protection and run down onto the underlying structure, further degrading the structure appearance.
Climates exposed to more intense UV rays for longer periods of time will experience chalking sooner as environment plays a big role in how painted steel will perform. While a client may not be able to control how much UV or moisture exposure their roof gets, they can choose a paint system not over-thinned or over-spread and using high quality components.
Shopping for a new painted steel covered building? Please avoid being disappointed years from now, like our client from South Carolina. If who you are talking to about a new building investment does not mention steel paint warranties – ask them. Know what it is they are proposing.
Also consider choosing a paint color which will least show fading and chalking, such as white or tan.
In markets where it is available I always recommend going with best possible paint system available – PVDF. Read more about PVDF’s benefits here: https://www.hansenpolebuildings.com/2014/05/kynar/.