Monthly Archives: August 2012

Metal Roof Coatings: What to Look for When Choosing a Durable Topcoat

When architects and building owners are looking for specific performance characteristics in choosing a metal roof, they are inevitably looking for its coating to act as a continuous barrier, adhere tightly to the substrate, and not fade, peel or chip over its life. They expect it to be hard enough to resist incidental scratches from transportation, installation, and roof traffic and impact. They do not expect it to be so brittle as to crack during metal forming. They want it to resist damage from atmospheric chemicals and salt and not chalk, fade, lose gloss, or stain. In other words, they want the coating system to be durable, enhancing the life of the metal roof underneath and extending the guarantee that the product will perform effectively for many years.

There are dozens of tests that paints can undergo to determine their performance characteristics for durability (See National Coil Coating Association Tool Kit #8). There are falling sand erosion tests, acid tests, adhesion after impact and bending tests and acid rain and salt spray simulations.  Fade, chalk and gloss are the most important characteristics measured in weathering tests.

Paints are usually identified by a resin type such as polyester, urethane, latex, etc. Tradeoffs in creating these systems are made to meet different price points for different needs. But, paints should also be considered as complete systems, rather than as a simple addition of a better or cheaper part of the product.Metal roof coating colors

Let’s dig a little bit more deeply to see what makes the difference in a superior metal roof coating. There are several coil coating topcoats available but only three are used primarily for coil coating exterior metal like that which is found on a standing seam metal roof system. Polyesters have traditionally occupied the low end of the market. They offer a hard, scratch-resistant finish and a wide range of gloss. But polyesters are prone to chalking when exposed to UV or sunlight. Since their introduction in the 1960’s, polyesters have been greatly improved with higher molecular weights and longer polymeric chains that create stronger, more UV-resistant bonds.

Silicone-modified polyesters (SMP), also known as silicone-protected and siliconized polyesters, use polymerized silicone to improve polyester chalk performance and gloss retention. But one disadvantage of silicone polyesters is lower flexibility due to the highly crosslinked and branched structure of these polymers. Continue reading

Manufacturing Metal Roof Systems More Efficiently On the Job Site With Portable Roll Forming Machines

Standing seam metal roof panels are formed for a project in one of two ways— directly at the job site using a portable roll former or off site at a factory and transported by truck to the job site.

When on-site portable roll forming first appeared on the scene more than 25 years ago, the sellers of factory formed panels saw the threat of losing business to metal roofing companies that formed the metal roof panels at the job site using portable roll forming equipment that provided greater flexibility and job control.  These in plant manufacturers began to make a lot of noise about the perceived disadvantages of on-site manufacturing.  Their unfounded claims were that on-site roll forming was too new and lacked a proven track record.   They focused a great deal of time and effort trying to disparage and eliminate the competition from on-site metal roofing fabricators.

Despite their great protestations, job site roll forming has thrived and millions of metal roofs have been installed using portable roll forming machines.  In fact, during the intervening years metal roofing projects completed using portable roll forming equipment have not received any more complaints than those projects that were completed using factory formed panels.  In many cases the advantages with respect to flexibility and increased job control resulting from the more efficient on-site roll forming process drew raves from GC’s, Architects and Building Owners.

Recently, times have been tough in the building industry—we all know that. And twenty five years later the sellers of factory-made panels are feeling the pinch and protesting again—from their factories, hundreds and sometimes thousands of miles from the job site where their roofing panels are being installed.

Twenty five years later, they’re still obsessed with the competition and still complaining about product reliability issues which were clearly never an issue in the first place. Meanwhile, job site roll formers have proven to have several distinct advantages over factory-made panels.

Unlike sellers of the factory formed panels, they don’t store piles of standing seam metal roof panels at the job site only to wait until other crafts have completed their work before roof installation can begin. They don’t leave panels exposed to inclement weather. They don’t have to worry about possible shipping and job site damage.  And they never have to worry that the panels will be too long or too short or that there weren’t enough panels manufactured and sent to the job site in the first place.


Conversely, job site roll formers are able to accommodate last minute changes in plans without waiting several days for the factory to take the order, make the new panels and ship them back to the job site.  Meanwhile, sophisticated roll forming machines allow contractors to punch in 50 different programs and get a series of different panel lengths in sequence.  Today’s contractors produce panel lengths in batches—without touching the unit.

Polyurethane drive rollers drive all materials up to 24 gauge steel through a machine with ease.  A wide variety of materials are run through the machine, with little or no adjustments.

The use of AutoCAD and CAD in the machine design process has resulted in shorter machines that produce finished panels and gutter systems in record time.

And… due to the resulting quality and efficiency more and more architects and GCs are turning to on site metal roof fabricators as the preferred choice to manufacture their clients metal roof systems.

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