Quick Answer: You just power-wash the roof clean and apply additional coating.
Quick Story: I was manning our booth at the Ohio School Board Association in November 2025. Two different people saw a sample of a roof coating system sitting on our table:
And they asked me, “What happens when the coating wears away?”
The Complete Answer: When an elastomeric roof coating system is installed, the warranty is determined by the coating thickness.
- A 20-mil dry-film thickness will provide a 10-year warranty.
- A 25-mil dry-film thickness will provide a 15-year warranty.
- A 30-mil dry-film thickness will provide a 20-year warranty.
Let’s say that the 30-mil/20-year warranty system was installed.
In year 20, there should be a few mils of coating left.
The elastomeric coating is designed to wear away naturally over time.
Coating manufacturers have done extensive testing to determine how long a certain coating thickness will last. I’m not sure, but I bet if 30 mils are installed…there’s almost a 99.999% chance there will be coating left after year 20.
Now that we got that out of the way, what happens next…
When a coating system is installed, a maintenance contract may be included. This allows the installing contractor to visit the roof twice per year and look for many things, including:
- If drains are clogged
- If gutters are clogged
- If there’s any evidence of thin coating
- Any weather-related damages, such as hail damage
- Damage from animals
Amongst many other things.
The point is to ensure the coating system is functioning as intended and that nothing interferes with its performance.
Fast forward to year 20.
The roof is in good condition (it’s been maintained every Spring/Fall for the past 20 years) and has 3 mils of coating remaining.
The contractor simply powerwashes the roof clean at the specified PSI per manufacturer specifications, ensuring a clean membrane.
The membrane needs to be very, very clean so that the new coating being installed adheres to what’s already there.
The contractor then installs a new 30-mil-thickness of coating. And a new 20-year warranty is granted.
Conclusion
The simple answer is that the coating naturally wears away; when it’s almost gone, the roof is cleaned, and more coating is installed.
Hopefully, after this post, you’ve learned that there are other things involved, such as maintenance.
Want to learn more about roof coating systems? Here are some other questions property managers want to know about:
- Is my commercial roof eligible for a coating system installation?
- How much does a roof coating system usually cost per square foot?
- What common problems do roof coating systems have?
If videos are your thing, we have over 450 videos on our YouTube Channel. Many are 15-30-second clips of roof-coating installations.
