After gauge and color, the next choice on a metal roof order is the finish: the coating that protects the steel and gives the roof its look. The panels we order come in three:
- Bare Galvalume, the unpainted silver finish
- SMP, the standard painted finish
- PVDF, a premium paint system
All three start from the same place: steel coated with Galvalume, an aluminum-zinc alloy that protects it from rust. On the panels we order that coating is AZ50, a common weight for metal roofing. The difference between the three is what goes on top.
Bare Galvalume
This is the Galvalume coating with no paint over it. It has a bright, spangled silver look that weathers to a softer matte gray.
Good for: barns, shops, sheds and agricultural buildings where cost matters more than color.
Why people choose it: it's the least expensive option, and when it's new the bright surface reflects a lot of sun.
Watch out for:
- Wet concrete and mortar. They're alkaline and can damage the coating. Keep bare Galvalume from sitting in contact with them.
- Livestock buildings. Ammonia from manure is hard on the coating. Bare Galvalume isn't recommended for enclosed animal confinement buildings.
- Mixing metals. Water that runs off copper, or contact with lead, can corrode the coating. Tell us if the roof will be near either one.
SMP (silicone-modified polyester)
SMP is the painted finish on most exposed-fastener metal roofing, and for good reason. It holds its color well for the price and comes in a wide range of colors.
Good for: homes, porches, barns, shops and most everyday metal buildings.
Why people choose it: you get color, a long-lasting finish and good value in one. It's the most common choice for homes and farm buildings.
PVDF
PVDF is a premium paint system built on fluoropolymer resin. Its big advantage is how well it resists fading and chalking over the years.
Good for: commercial and architectural buildings, and any project where the color has to look right for a long time.
Why people choose it: it keeps its color longer than SMP, especially in hard sun. It costs more, so it makes the most sense where appearance really matters.
Side by side
| Bare Galvalume | SMP | PVDF | |
|---|---|---|---|
| Look | Silver, weathers to matte gray | Wide color range | Wide color range |
| Color life | No paint to fade | Good | Best |
| Cost | Lowest | Moderate | Highest |
| Typical use | Barns, shops, ag buildings | Homes, barns, shops | Commercial, architectural |
Things that matter here in Louisiana
Sun and heat. Every painted finish slowly fades and chalks under strong sun. Deep, saturated colors show it sooner than light, neutral ones. Lighter colors also reflect more heat, which can make a real difference in a shop or attic in August.
Salt air. If the building sits close to salt water, tell us when you order. Some warranties are limited near the coast, and it can change which finish we'd recommend.
Warranty. Coverage depends on the finish and the exact panel. Before you order, ask us for the written warranty on the panel you're buying so you know exactly what's covered.
Our take
For most homes and farm buildings, SMP is the sweet spot. For a working barn or shop where looks come second, bare Galvalume saves money. For a commercial front or a color you need to hold for decades, PVDF is worth the upgrade.
Ask us for a color chart. See the panel profiles and specifications we order, and if you're still choosing thickness, read 26 vs. 29 gauge metal roofing.