Are you concerned about your roof rusting or fading faster than it should in Seattle's rainy weather? Have you heard of roof coatings but don’t understand the difference between PVDF, SMP, or stone-coated finishes (or why it even matters for your investment)?
If you live in a wet climate like Seattle, picking the wrong metal roof coating can mean thousands of dollars in premature repairs.
At RoofSmart, we’ve helped hundreds of Seattle-area homeowners choose the right type of metal roof and coating to best meet their budget and preferences. We understand that it’s hard to tell which coatings work best and which ones aren’t even worth the money.
In this article, we’ll explain the four main types of metal roof coatings, how each one performs, and how to choose the right option for your home and climate.
Why do metal roof coatings matter?
Steel roofs (and sometimes aluminum) need a coating to protect the base metal and the paint. 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 is an indication that the roof’s protective coating has started to break down after too much sun exposure. The coating will slowly wear off, leaving your roof vulnerable to damage and rusting.
- Corrosion: In a wet, rainy area like Seattle, you need the right coating to protect 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 coating is what allows your metal roof to be durable for 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-quality coating for your roof, you’ll be stuck paying thousands of dollars to repair or replace an already expensive roof.
What are the 3 types of metal roof coatings?
There are many different brands and variations of metal roof coatings, but this can all be narrowed 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 type of metal roof coating. It’s also the most widely available because it offers the best protection.
For best results, make sure that the supplier is using a coating that is made of 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 is a mid-level roof coating 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 roof coating is a less commonly used coating. It provides some protection for your roof, but it is not a strong or long-lasting as the other coating options.
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 other metal coatings?
Most steel or aluminum metal roofing panels will get one of the three coatings covered in this article. However, stone-coated stamped panels have a special coating 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 coating is only available if you specifically want 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 coating is best for my Seattle area home?
Choosing the right coating to protect your roof means considering your preferences and budget. You’re already spending plenty of money on the metal roof, so make sure that you pick a coating that can last long enough for the cost to be worth it.
Factors to consider when choosing a roof coating:
- Longevity and durability
- Cost
- Corrosion resistance
- UV resistance
Choosing a metal roof coating can be confusing, but your roofing contractor can help you pick one. 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 Metal Roof Coating?
Now that you understand the pros and cons of the main types of metal roof coatings (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 understanding coatings is only part of the puzzle. 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—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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