Are you concerned about your roof rusting or fading faster than it should in Seattle's rainy weather? Have you heard of PVDF, SMP, or stone-coated finishes but don’t know the difference (or why it matters for your investment)?
In a wet climate like Seattle, picking the wrong paint system on a metal roof can mean premature repairs.
At RoofSmart, we help homeowners choose the right metal roof and paint system for their budget and preferences. It’s hard to tell which paint systems hold up and which aren’t worth the money.
In this article, we’ll explain the four main metal roof finishes (three paint systems plus stone-coated), how each one performs, and how to choose the right option for your home and climate.
Why does the paint system on a metal roof matter?
Steel roofs (and sometimes aluminum) need a factory paint system to protect the base metal. It prevents things like:
- Chipping, cracking, or peeling paint: Obviously, this kind of damage looks bad. It also means that your roof is exposed to the elements and prone to rusting.
- Chalking: This is when you notice that your roof has a dusty white layer over it. Chalking means the paint system has started to break down after too much sun exposure. The finish will slowly wear off, leaving your roof vulnerable to damage and rusting.
- Corrosion: In a wet, rainy area like Seattle, you need the right paint system to keep your roof from rusting. If rusting starts to happen, that means your roof isn’t protecting your home, and it needs to be replaced.
The paint system is what lets your metal roof last as long as possible. Without it, steel and aluminum roofs would have a much shorter lifespan.
Not only do damaged metal roofs look bad, but they also leave your home vulnerable to leaks or other issues. If you don’t choose a good paint system, you can end up paying to repair or replace an already expensive roof.
What are the 3 types of metal roof paint systems?
There are many brands and variations of metal roof paint systems, but they come down to 3 common types:
- PVDF
- SMP
- Polyester
There are pros and cons to each option. It's important to understand the full picture before making your final decision.
1. PVDF
PVDF stands for polyvinylidene fluoride. This is the strongest and longest-lasting metal roof paint system. It’s also the most widely available because it offers the best protection.
For best results, make sure the supplier’s paint system is at least 70% PVDF. Anything below 70% will not have as good protection and durability.
Big brand names like Kynar 500 have the right amount, but other brands might not. Make sure you check with your roofer to ensure that you’re getting the best roof protection possible.
Pros:
- Available on any gauge of metal
- Usually has 40-year warranty protection
- Large variety of color options
- Most resistant to chalking and fading
Cons:
- Most expensive option
- Easier to scratch or scuff than SMP
2. SMP
SMP means silicone-modified polyester. It’s a mid-level paint system with a polyester base, but it’s stronger and more durable than regular polyester because it has silicone mixed in.
Pros:
- Very scratch-resistant (the paint is harder than the paint on PVDF)
- Lower cost than PVDF, but still offers good protection
- Good for keeping out moisture
Cons:
- Chalks and fades faster than PVDF (but still lasts 10 to 20 years before chalking)
- Color fades quicker than PVDF
- Usually only available on thinner gauges
3. Polyester
Polyester-resin paint is less common. It gives some protection, but it isn’t as strong or long-lasting as the other paint systems.
Pros:
- Least expensive option
Cons:
- Very little UV resistance
- Best for indoor use
- Will start chalking in 5 to 10 years
- Only available on thinner, lower-quality metal
How does stone-coated metal compare to painted metal?
Most steel or aluminum panels get one of the three paint systems in this article. Stone-coated stamped panels have a stone-granule finish that looks different but still protects them from damage. It's used to protect the roof and elevate your home's curb appeal by imitating the look of tile.
The metal is first covered in a layer of glue, and then it gets dusted with shingle grit. This is similar to the granule layer used on asphalt shingles to protect them from breaking down.
This finish only comes on stone-coated stamped metal panels. It is not available on any other type of metal panel.
Here are the pros and cons:
Pros:
- Durable
- Very scratch resistant
- No chalking or fading
- Lasts 50+ years
Cons:
- Susceptible to growing moss or algae
- Collects debris easily
Which metal roof paint system is best for my Seattle-area home?
Choosing the right paint system comes down to your preferences and budget. You’re already spending plenty of money on the metal roof, so pick a paint system that lasts long enough to be worth the cost.
What to weigh when choosing a paint system:
- Longevity and durability
- Cost
- Corrosion resistance
- UV resistance
Choosing a paint system can be confusing. A good roofer should explain the options after looking at your roof. Make sure that you choose a roofing contractor who is trustworthy and experienced.
Not sure how to know if your roofing contractor is trustworthy and experienced? Download our Qualified Roofer Checklist and evaluate your roofer options with confidence.
What’s the Next Step After Choosing a Paint System?
Now that you understand the pros and cons of the main metal roof finishes (PVDF, SMP, polyester, and stone-coated), you’re in a much better position to protect your investment and extend the life of your roof.
But the paint system is only part of the picture. The next logical step is understanding the actual cost of installing a metal roof in the Seattle area, so you can align your budget with the level of protection you want.
Read our article “How Much Does It Cost to Install a Metal Roof in the Greater Seattle Area?” to see what pricing looks like and what factors impact it.
Whether you're still comparing materials or getting ready to book a project, you'll walk away knowing exactly what to expect, with no surprises.
To get a ballpark estimate of how much it will cost to install a new metal roof on your home, use our Instant Estimator tool.
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