PVDF vs SMP metal roofing comes down to how long the paint keeps its color and reflectance: 70% PVDF (polyvinylidene fluoride) finishes resist chalking and fading best and cost more, while SMP (silicone-modified polyester) finishes are harder, cost less and hold up well, but chalk and fade more over the years. Because an energy-efficient metal roof depends on its surface reflecting sunlight, the finish decides whether the roof stays efficient for decades or slowly loses performance. For help choosing a finish, call NEMA Roofing at 866-631-3366.
What is the difference between PVDF and SMP finishes?
Both are factory coil coatings: the steel or aluminum is cleaned, pretreated, roll-coated and oven-cured before it is formed into panels. The difference is the resin that binds the pigments. One coil coating maker, Sherwin-Williams, rates its own products this way:
| Property | SMP (silicone-modified polyester) | 70% PVDF |
|---|---|---|
| Chalk resistance | Very good | Excellent |
| Fade resistance | Very good | Excellent |
| Dirt resistance | Very good | Excellent |
| Hardness (scratch resistance) | Very good | Good |
| Flexibility | Good | Excellent |
| Relative applied cost | Lower | Higher |
PPG, another coil coating maker, describes PVDF as best with intense sun exposure and offering color stability for decades, and SMP as a popular choice for residential, industrial and agricultural buildings because of its price-to-performance ratio. Both can be made in solar-reflective (cool) colors. Chalking is the powdery residue left as a paint film breaks down; fading is the color shift that goes with it.
Why does the finish decide how efficient the roof stays?
A cool metal roof works by reflecting sunlight and shedding the heat it does absorb. The Cool Roof Rating Council rates roofing products when new and again after three years of weathering at an approved outdoor test farm. California’s Energy Commission uses the aged values for Title 24 compliance.
That gives you a practical test. In the CRRC Rated Roof Products Directory, look up the colors you are considering and compare the initial solar reflectance with the three-year aged value. A small drop means the finish resists chalk and dirt; a large drop means the roof will run warmer as it ages. Comparing the same color in a PVDF line and an SMP line shows you the difference for the exact product, not in general.
Pigments matter too. Sherwin-Williams notes that organic pigments give brighter, higher-chroma colors but are less stable in sunlight and heat than inorganic (ceramic) pigments. The U.S. Department of Defense roofing criteria (UFC 3-110-03) specify 70% PVDF resin with 100% inorganic pigments for exterior metal roofing. For the reflectance numbers the code requires in each climate zone, see the guide to energy efficient metal roofing in every climate.
Which finish suits which home?
- Hot, sunny inland valleys: PVDF, which PPG describes as best with intense sun exposure.
- Deep or bright colors: PVDF with inorganic pigments; bright colors often depend on organic pigments, the kind Sherwin-Williams notes are less stable in sun and heat.
- Near the ocean: PVDF, ideally over aluminum or a coastal-grade system; Sherwin-Williams offers a heavier 70% PVDF system specifically for coastal and corrosive settings. The military criteria prefer aluminum panels with a PVDF coating in corrosive environments.
- Sheds, barns, workshops and budget-driven projects: SMP, which gives good service at a lower cost.
- Roofs that see foot traffic or tree limbs: SMP is the harder film, though a scratch on either finish should be touched up.
- Light cool colors on a house: either can work; compare the aged reflectance of the specific products.
Which metal to put under the paint is a separate choice, covered in the best metal roofing material for each climate.
How do you confirm which finish you are getting?
Quotes often say only “painted steel” or name a color. Ask for these in writing:
- The coating’s product name and resin. For PVDF, the resin share should be 70%. Arkema, which makes Kynar 500 PVDF resin, requires its licensees to use at least 70% by weight and points specifiers to the AAMA 2605 performance standard.
- The pigment type, especially for dark or bright colors.
- Film thickness. The military criteria call for at least 1 mil of dry film: a 0.2 mil primer and a 0.8 mil finish coat.
- The CRRC product ID with initial and three-year aged reflectance and emittance for the color.
- The finish warranty: what it covers for chalk and fade, how each is measured and what happens if the limits are exceeded.
- The metallic coating under the paint (for steel, aluminum-zinc such as AZ50), which protects the steel where the paint is cut.
How do you keep a metal finish performing for decades?
- Follow the panel maker’s care instructions; mild washing is enough for most roofs.
- Avoid abrasive pads, wire brushes and harsh solvents, which remove the finish they are meant to clean.
- Rinse salt from areas rain does not reach if you live near the coast; the coastal metal roof maintenance guide explains how.
- Touch up scratches with the maker’s matching paint so the metallic coating underneath is not left exposed.
- Keep trees trimmed back so branches do not scrub the surface in wind.
Choosing a long-lasting finish with NEMA Roofing
NEMA Roofing’s crews install metal roofs in every town of Los Angeles, Ventura, Santa Barbara, San Bernardino and Riverside counties, working out of five locations in Downey, Tarzana, Woodland Hills, Oxnard and Santa Barbara, so both salt-air coastal towns and the hottest inland valleys are covered; see the full list on our service areas page. Compare systems on our metal roofing service page, or call 866-631-3366 for an estimate that names the coating, its resin and its aged reflectance.
