Is there anyway to tell when inspecting a flat roof how many ply’s there are just by eyeballing. The new owner was told by the previous owner the roof was replaced 4 years ago however no permit for the work is on file. If the roof is a 2 ply then it would have a life expectancy of 5-10 years, if 5 ply i understand that it could have a life expectancy up to 15 years. Need to determine life expectancy for a Roof Certification I am doing on a home insured by Citizens of Florida. Thanks
Bob
Simply put…
NO
You would need to do core sampling or some sort of destructive testing if the roof is installed properly in order to determine the number of layers.
It is sad, and I have read throughout this message board how inspectors go way above any SOP’s, think they know everything, and end up complaining about litigation and lawsuits.
Wake up people. Your job is to observe accessible areas, recommend repairs, document what you see, inform the buyer, and let them decide where/how to proceed.
Read all of Joe Ferry’s blogs. http://joeferry.com/
You need to quit worrying about attorneys and lawsuits Scott did not tell him to take a core sample simply stated that core samples was the only way to determine thickness on a flat roof
If you are qualified to do roof certifications, shouldn’t you know? I don’t think you do. Do you have a good attorney? 
There are ways of seeing the ply but it is hard and the answer in 90 percent of the cases is no.
A roll of felt is 36inches wide.
The ply would be how many full overlaps.
I installed a photo image for you to understand.
On a normal residential roof " 4 PLY IS THE NORM." In my area. Zone 5 weather.
3 plys GO DOWN IN MOST CASES. ALTHOUGH THEY SAY 4 PLY EVEN ON THE CONTRACT. That is another story.
They should dry tack one full “dry ply”,( cheats count that ply ) after stripping the roof for a proper re-installation. On a " dry ply of starter ply " no tar is being used. It enables the next roofer to strip the roof without having difficulty. ( being moped to the roof deck ) makes the stripping of a roof a night-mere.
That is another story.Bad roofers. But I here it everywhere.
*If there is no gravel on bare spots you can count the ply with a tape measure. *
Expand your tape 36 inches. Count the laps or ply’s.
Even if you have 20 inches bare, do the math it takes to get how many ply if it was 36 inches wide.
I hope you are with me. I hope I am explaining it well.
Email me if you need more info. I am a roofer but have not plied my trade for 15 plus years now.( Thank God )
The photo is a 2 ply. It might be 4 or even 6 ply at the end. 2+2= 4 or 2+2+2 =6. It depends on many factors how the site foreman ( me at times ) wants to work that day and that roofing system.