That simple marking told a big story.
Last week, after the snow and ice finally cleared here in Dayton, Cotterman & Company Inc. completed a roof evaluation on a large warehouse facility that had recently started experiencing leaks.
As part of the inspection, a date stamp was located on the membrane: DL ’99.
That simple marking told a big story.
The building is protected by a Duro-Last PVC roofing system that was installed in 1999. After 25 years of service, the system has performed well — a testament to proper installation, maintenance, and the long-term durability of PVC roofing systems in commercial applications.
However, even well-performing systems eventually reach the end of their service life. With leaks beginning to show and the roof now at the 25-year mark, the timing makes sense to begin planning for replacement rather than continuing reactive repairs.
Cotterman & Company Inc. has provided reroof options so the customer can evaluate what best fits their long-term goals and budget. A key part of the discussion is warranty coverage. Once a new roofing system is installed, the facility can secure:
- 20-year
- 25-year
- 30-year
Watertight material and labor manufacturer warranties — helping protect their investment for decades to come.
Finding a date stamp during an evaluation may seem like a small detail, but it provides valuable insight. It helps establish system age, guide realistic expectations, and support proactive planning instead of emergency decision-making.
If you manage or own a commercial facility and are unsure of your roof’s age or condition, a professional evaluation can provide clarity — and help you plan ahead before minor leaks turn into major disruptions.
Date stamp was located on the membrane: DL ’99.
View of the roof that's over 25 years old.

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