Proper maintenance is essential to ensure a roof system warranty remains valid. On average, a roof installed with a 25-year warranty and no proactive maintenance will last just 10 years before a new roof system will be necessary to prevent damage to your property. That also means your warranty will be void due to lack of maintenance.

If minimal maintenance is performed, you can expect a 15-year service life (See above for definition) before a new roof is needed.

If a proper maintenance program is established and followed, along with a low-cost restoration,  the roof will last the full 25 years plus an additional 10 years.

In the above graphic, you can see an initial roof cost of $25,000 and three different “maintenance plans.”

With no maintenance plan, you will need to re-roof your property at year 10 at a higher cost due to inflation. At year 20, you must replace the roof again at an even higher cost.

With minimal maintenance, you will need to re-roof at 15 years, giving you 30 total years of life.

With a full maintenance plan, no re-roof is needed during the warranty period, but a low-cost restoration (coating of the roof, flashing repair, small replacements of membrane or insulation) should be performed at 15 years to extend the roof warranty and life to a total of 35 years.

https://www.roofingcontractor.com/articles/86719-why-roof-maintenance-pays

https://facilityexecutive.com/2016/08/roofing-maintenance-dollars-and-sense/