Residential and Commercial Metal Pole Building Painting | DJ’s Painting

Metal pole building painting is often an over looked project. Most pole buildings have a metal outer shell, meaning the walls, roof, and all trim are steel or aluminum.  90% of the time this metal is either a powder-coated, baked paint finish or a galvanized coated finish. These are great for long term outdoor exposure.  Both systems hold up well to the UV and moisture over time and do a great job of protecting the metal from oxidation.

The problem comes in when people believe the manufactures' claim that the metal never needs to be painted. Truth of the matter is the coated metal is punctured with screws and various fasteners. The dirt and other contaminates that are laying on the surface create extra stress on the coatings and break them down prematurely. When the coatings break down, the metal is left vulnerable, even if it’s just little areas here and there… These areas start to oxidize or “rust” and break down. This can be very expensive to fix, and not to mention it is just plain ugly… On walls, it will last anywhere from 15-20 years before the coating starts to fail, but roofs fail a little faster due to more direct UV and rain exposures.

So now that we have established that factory finished metal is not a lifetime coating but in fact a decade or 2, we can talk about how to maintain and extend its life.

First, the surface needs to be clean and chalk free. The best way to achieve this is to pressure wash the area completely. Then, the next step is to apply a complete prime coat, the material that best primes will vary depending on the situation we are dealing with. In the case of a baked finish, which is a very hard coating and difficult for water based coatings to get a good bond, we use either a phenolic alkyd oil based bonding primer or a 2 part solvent based mastic epoxy bonding primer.

The epoxy works better, especially for rusted metal, however, the phenolic is less expensive and easier to use.  If it’s galvanized, a  water-based bonding primer or epoxy is best since Alkyd can react with the zinc and cause the primer to lift after a few years…    

Metal building with a fresh coat of exterior paint

Painters painting the exterior of a steel building

Metal roof painting, South Jersey

For the top coat, you have some options based on desired results. For best color and gloss retention, a 2 part aliphatic urethane top coat is best and should last 10 plus years. For a more economical coating, a DTM or waterborne single component urethane will work well and give about 5 years of good color retention. We strongly recommend washing, followed by repainting with the same top coat at the 5 or 10 year time frame. This will help to keep cost down.  

It is a good idea to stay on a re-coat cycle of about 5 years for single component top coat systems and 10 years for 2 component top coat systems. The reason for this is that on a roof or horizontal surface, the single component paints will “weather away” at a rate of about ½ a mil per year after the first year. 2 part urethanes weather away a little slower, allowing more time in between re-coats.  If the coating is allowed to weather away completely, leaving the primer exposed, the primer will break down in just a few months under the suns UV rays. The rust will start over, requiring another prime coat and additional prep… also if the top coat is left to long it may begin to loose adhesion causing a problem for the future top coats for years to come…

Bottom line is this, if you stay on top of the maintenance painting of your metal or steel pole building it will last a lifetime!