Salt air starts working on a coastal metal roof the day it goes on, and it doesn’t wait for a hurricane. Coastal metal roof installation lasts the full service life when the whole system is built for the site: flashings detailed with care, stainless and aluminum components, sealed cut edges, and clips that let the panels move.
That’s the working playbook Edward Montemayor laid out on Episode 70 of the Building With Metal podcast. Edward is the operations manager and marketing director at South Texas Metal Roofing in Corpus Christi, a family business on the Texas Coastal Bend. His father started in metal roofing in Houston in the early 1970s, and together they have about 50 years in the trade. Here’s what his crews do differently on the coast, in his words, wherever possible.
On the Gulf Coast, Edward points to the water first. “We have very high salinity in our ocean, so it doesn’t take a hurricane or storm for the environment to beat up a roofing system.”
Salt exposure is constant, and it finds the weakest part of the assembly. Host Kathi Miller put it the way McElroy always does: “We always say that a metal panel itself doesn’t leak, right? It’s all the conditions around it.”
Edward sees the same misunderstanding among homeowners and contractors. “The misconception is that just because you’re putting a metal panel on your house, you automatically have a 50-year roof. You could potentially have that, but if it’s installed incorrectly, it will fail and cause issues.” In his view, the right waterproofing, the right components, ZIP tape on the deck, and proper counter flashing give a roof a 50- to 70-year life.
When Kathi asked Edward what contractors do that shortens a metal roof’s life, he didn’t hesitate. “The biggest mistake in the industry is flashings. That’s your first line of defense: counter flashings, chimney flashings, and step flashings. Those take a little more detail, and I’ve seen a lot of guys want to rush things.”
The damage shows up later. “Those are areas where water infiltrates, gets into the system, and gets under your panels. Then you have issues that can arise from moisture being held in there.”
Flashings are also where Edward would look first on a roof that’s been in service for five years. He’d check every flashing and penetration: pipes, jacks, ridge, counter flashings, and step flashings. “Those are the areas that expand and contract and can allow water entry if they’re not done correctly.”
McElroy’s field experience matches his. When McElroy is called out to look at a leak or a problem roof, Kathi said, flashings are a big starting point. McElroy publishes trim and flashing details for its panel systems, and working from the manufacturer’s detail for each condition is the simplest way to take the guesswork out of those areas.
Edward treats the roof as one assembly where every part has to hold up together. “It is a full system. It’s not just a metal panel being installed. Everything is bound together and has to work together.”
On the coast, that shapes the material list. Edward shares, “Here on the coast, that means staying away from zinc-plated screws and galvanized steel components and sticking with 316 stainless steel.” South Texas Metal Roofing fabricates its own roof jacks from aluminum or stainless steel for the same reason, and the company leans on aluminum panel systems backed by a manufacturer’s coastal warranty.
Kathi tied that to the family name. When your name has been on the building for 50 years, “you’re not going to take shortcuts that might make a building last 10 years less.” Edward agreed.
McElroy applies the same reasoning to roof curbs. On weathertight warranty projects, Kathi explained, McElroy requires a .080-inch aluminum curb, even though some competitors allow galvanized. Experience showed that a galvanized curb is likely to fail before a roof designed to last 50 to 60 years does, while the .080-wall aluminum curb will not.
Edward is specific about where the trouble starts in coastal projects. “Those corners and trims where you make a cut and typically don’t have a hem are exposed areas where the coating has been broken.”
His crews treat every one of them. “We prime them and coat them.” The manufacturer usually ships bottles of the same PVDF paint system that comes on the material, so the touch-up matches the panel finish.
Five years in, Edward would inspect the paint system across the panels for spots where debris has hit the roof and exposed the AZ50 Galvalume® substrate underneath. On the coast, with constant salt exposure and material compatibility issues, that’s where corrosion gets started.
McElroy offers its panels in Kynar 500® PVDF resin-based coating and SMP paint systems. On coastal work, ordering matching touch-up with the material means field cuts end up on the same paint system as the rest of the roof.
In the Coastal Bend, Edward’s crews start with the specifications. “Down here on the coast, we do need a certified engineer involved. They go through the manufacturer’s specifications, and then we install the system accordingly, making sure we’re using the right clips, whether that’s a fixed clip or a two-piece clip, to allow for thermal expansion and contraction.”
Then it’s on the crew. Edward watches for over-tightened fasteners. “That can cause more severe oil canning or panels to buckle when crews are moving fast and trying to get through the day.”
Kathi said improper pinning is one of the biggest problems McElroy finds in the field. “People don’t think they’re creating a problem when they install it, but after a couple of years of thermal cycling, it can really start to cause problems if it’s not done properly.”
That’s the second thing Edward would check on a five-year-old roof: how the panels are handling expansion and contraction. Pinning errors don’t show up on the day the roof is finished.
Edward likes the control that comes with forming on site. “Roll forming on site gives you a big benefit because you can quality-control the panels and their length, making sure they’re coming out correctly with no deformation. You can stop production with the touch of a button.”
On a large commercial roof, Kathi pointed out, a 250-foot panel can eliminate maybe three or four splices. That cuts install time and removes one of the roof's weaker points: the panel lap.
On-site forming helps on residential jobs too. Factory panels sometimes get dropped in front of a homeowner’s house, and the homeowner worries when it starts raining on a stack of panels. Forming as the job progresses avoids that.
| On-site roll forming | Factory-formed panels | |
|---|---|---|
| Quality control | Crew checks length and deformation as panels come off the machine, and can stop production at the push of a button | Panels arrive ready to install |
| Panel length | Crew can measure and modify day of production | For long runs, McElroy can form panels on site up to 250' |
| Job site | Panels formed as the job moves; nothing sits in the yard | Panels delivered and stored on site until installed |
| When the spec decides | Works when the spec allows contractor-formed panels | Required when the spec names a manufacturer, an NDL warranty, or a weathertight warranty |
South Texas Metal Roofing buys much of its coil from McElroy and has used McElroy’s Maxima 2-inch standing seam panel on commercial buildings. The company also installed McElroy matte black mechanically locked standing seam across a subdivision that mixed metal and shingle homes. As Kathi noted, job-site production has advantages on certain projects, whether McElroy forms the panels or the contractor does.
FORTIFIED™ is a voluntary roof standard from the Insurance Institute for Business & Home Safety (IBHS) that calls for a sealed roof deck, stronger deck attachment, and stronger roof edges. Contractors must pass an application and a demanding test to install it. On the Texas coast, builders and vacation-home buyers ask for FORTIFIED™ roofs because they may lower insurance costs.
Edward says South Texas Metal Roofing is one of three FORTIFIED™ roofing companies working in the coastal area, and he expects the program to shape the next 10 years of the company’s work. Getting there took effort. “It’s somewhat like getting a certification from a manufacturer, but it’s really intense and requires a lot of studying. I’ll be honest, the test was not easy.”
The deck work is a big part of it. Edward’s crews ZIP tape the roof decks to keep water out of the home. According to IBHS, sealing the seams of a roof deck can reduce water intrusion by up to 95%.
Right now, the demand comes mostly from new construction. Builders want the system, and out-of-town buyers picking up vacation homes want it for the potential insurance savings.
The regulatory picture is still messy. Contractors in the Coastal Bend still need Windstorm certification, and it’s unclear whether FORTIFIED™ will eventually take its place. Edward hopes TWIA, FORTIFIED™, and Windstorm land on one plan for coastal homeowners within five years. For now, as Kathi put it, contractors are serving two or three masters.
FORTIFIED™ covers the deck and the edges. The metal roof over it still has to be installed to the manufacturer’s specifications and the project engineer’s clip and fastener plan, which is where the details in the sections above come back into play.
A metal roof in a coastal environment can last 50 to 70 years or more when the whole system is installed correctly. That includes proper flashings, the right waterproofing, and components that resist salt air. Edward Montemayor of South Texas Metal Roofing says a metal panel alone doesn’t guarantee that life, and an incorrect installation can fail far sooner.
South Texas Metal Roofing avoids zinc-plated screws and galvanized steel components on the Texas coast because high salinity corrodes them, even without a storm. The company pairs 316 stainless fasteners with aluminum or stainless steel roof jacks so every component holds up to the same salt exposure.
A galvanized roof curb is likely to fail before a properly specified and installed metal roof in a coastal application reaches its full service life. On weathertight warranty projects, McElroy Metal requires a .080-inch aluminum curb, even though some competitors allow galvanized. McElroy’s experience is that the aluminum curb holds up for a roof designed to last 50 to 60 years, while galvanized does not.
Roll forming on site gives contractors daily quality control, and long panels, up to 250 feet from companies like McElroy Metal, can remove end laps from the equation, which are the weakest part of any roofing system. South Texas Metal Roofing buys coil from McElroy Metal to form on-site and orders factory panels when the spec calls for them.
Over-tightened fasteners and improper panel pinning are common causes of oil canning and buckled panels on standing seam metal roofs. Both restrict the expansion and contraction the clips are designed to allow. The problem often isn’t visible at installation and shows up after a couple of years of thermal cycling, according to Kathi Miller of McElroy Metal.
A FORTIFIED™ roof may lower insurance costs, which is why builders and vacation-home buyers on the Texas coast often ask for it. FORTIFIED™ is a voluntary IBHS standard requiring a sealed roof deck and stronger deck attachment and edges. Contractors on the Texas Coastal Bend still need Windstorm certification as well, so homeowners should confirm requirements with their insurer and contractor.
Inspect flashings and penetrations first on an older metal roof: pipes, jacks, ridge, counter flashings, and step flashings. These areas expand and contract and can let water in if they were installed poorly. Next, check how the panels are handling thermal movement, then look for spots where debris has damaged the paint system and exposed the substrate.
Have a coastal project coming up? Contact us today, and we’ll help you work through the details.