I am also in FL, and I figure 30 to 40, based on my experience.
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I anyways say 35-40.
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There are too many variables. How close to the ocean is a big factor and quality of materials as well as installation. I have seen too many mistakes on roofs with valleys. 20 years is a sure thing. 50 years is possible with proper maintenance. New screws are a must and a painting half way through its life. Regular metal paint with primer is basic. Epoxy paint is so much better. Gako paint is supposed to be good for 50 years.
Bottom line is what is the condition today?
If rusty then maybe just a few more years….
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The table also displays more dumbness… Like clay/concrete roofs 100+ years
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The chart is incorrect. I can’t imagine many circumstances where a metal roof would only last 7-8 years longer than a 3-tab asphalt shingle (both being installed correctly).
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Compromise and say 17-50 years.
But, if you’re trying to determine remaining useful life, why does estimated useful life matter?
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Yeah, those are all messed up.
3 tab is 15-18, arch is 20-25, clay/concrete is 30-40, EDPM is 15-20, TPO is prob 20-25…
Whoever did this chart clearly was never an inspector in FL
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Agreed. You have done a better job getting to that point than I did.
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I think the main concern was relating to insurance companies, and the 4 point reports.
They want a basis to judge remaining life, because we are required to put an estimated number of years left on the 4 point.
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It all depends on the type of metal. My grandmother’s home had a metal roof that was older than she was. Alot of the old metal roofs in Deland are 100 years old and still in good condition. The difference between new metal and old metal is the metal. My son used to do metal roofing and did most of the schools and government building in South and Central Florida. Metal before 1990 was a better quality. The newer metal panels are not as thick and rely on the baked finish to extend the life of the metal. While there are guides and charts to help you know how long metal should last, they do not address things like engineering. thickness, and quality. This is something you pickup with experience.
I recently did a 12,000 sq ft home with a metal roof. The metal roof was 17 years old. It had large rust holes around the fasteners, in the valleys, and at the eaves of the roof. The metal roof coating was faded and had surface rust showing through.
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I understand. But what is the basis, an inspector’s experience or a generic chart? You said earlier “30 to 40 (years) based on my experience”. Is this your basis for ALL metal roofs no matter the current age and condition on the day of the inspection? Is a 15 year old poorly maintained metal roof going to last 5 more years or 25 more years?
I think my question got lost somewhere along the thread…
I really was only curious if everyone else thought the chart was as inaccurate as I thought or not.
For the record, I don’t go based off of any chart when determining remaining useful life, however, it is a good tool to use when I have to tell a customer they need a new roof. For some reason, homeowners will have a roof with half the shingles missing or rusted out metal and still give me a hard time when I say it’s time to replace it 
It always does. 
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No, point taken.
Just a starting point to judge, based on current appearance.
For example, I can look at an arch roof, and try to guess how old it is. And I am usually within a 1-3 years. If, however, I find out that the roof is newer than I thought it was, then I will reduce my original life span estimate, because it is wearing faster than normal.
Of course, this only comes with experience.
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It is also going to depend on the Gauge of the metal. Metal panels come in different gauges.
24 Gauge
26 Gauge
29 Gauge
and then also in different styles.
standing seam.
Ribbed panels.
Stone coated shingles.
Metal shake.
Metal slate.
Metal tile.
all of which have different life spans and warranties,
Ranging from 25 - lifetime warranties.
Some warranties are transferable some are not.
For more info you can visit Metal roofing
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They want a basis to judge remaining life, because we are required to put an estimated number of years left on the 4 point.
And what is the penalty if an inspector is incorrect on the RUL?
Hypothetically, what if an inspector continually states that there is 8-12 years left for the shingles and the insurance companies notice that they are replacing shingles after 2-5 years?
Do you know if the insurance companies keep tabs on all of the inspectors, regarding how accurate their data is? I would imagine they do but when do they start calling out the inspectors? If they are two years off, five years off, ten years off…?
I’m glad I don’t have to deal with that.
I’ve never heard of it being an issue before. I dont think they keep track, they just want a professional opinion on the condition.
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I have a cheat paper that states 40-80. Pretty sure I received it from InterNASHI
At install time there’s a difference between cuts by shears and cuts by grinders. In my area pros only use shears. They say the grinder edges boil off the zinc coating.
Hypothetically…nothing. Generally, most of us that perform these inspections find out when the roof was put on. Then, base the life expectancy on several factors onsite. Condition, presence of leaks, damaged wood, etc…
I inspected a roof, regular shingle that was 19 years old. It was perfect. On the other hand, I also inspected a tile roof which was poorly maintained, had several leaks, damaged wood, etc… and also 19 years old. Although it could have been repaired, good luck finding a roofer to do it.
In both cases, the insurance company required both clients to replace their roofs…
So, it doesn’t really matter what any inspector thinks…
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