This question finishes with no many nouns. I’ll break down some myths and facts about roofing today.
This is tough to tell, especially on architectural or rubber roofs. I’ll give a ball park estimate on homes I inspect. I’ll look to see when permits may have been pulled to do the roof as well. The main thing is what condition is it in. The typical 3 tab asphalt shingle lasts about 18-20 years. An architectural shingle can last 25-35 years depending on quality. A rubber roof can last 30-50 years.
There are things you can do to maximize it and things you can do to lower the lifespan.
The number one thing you can do for a long lifespan is a professional install right from day one. This includes strip all previous layers, repair sheeting, and install all new flashing. Did you know adding a second layer, although allowed by building code, voids your roofing warranty? It also drastically decreases the lifespan of the new roofing.
Next is proper maintenance of the roof. This meals clearing trees and vegetation from contacting the roof. Tree and shrub branches sway in the wind and destroy your roof. While you’re at it, cut them back from the siding too, but that’s another topic. Also proper lichen or moss removal. In these areas a roof, especially a shady one, can grow moss that will compromise the roof. There are treatments for removal. DO NOT POWER WASH YOUR ROOF!
The lifespan of roofing does decrease based on weather conditions sunlight, etc…it not a perfect science.
So this leads to the real question. How long will my roof last before it needs replacement?
Also tricky, and no estimate I may give you is a warranty, but there are signs of wear and tear that will allow me to help you determine an approximate lifespan.
Shingles that are badly cracked, broken or missing, or worn through have already failed.
Shingles that are curling or clawing. These are curled up or curled under are nearing the end of serviceability. Typically on the last 25% of the lifespan.
Shingles that have worn minerals. Minerals are the gravel like substance on the top. They protect the asphalt from the elements, when the minerals wear off the deterioration begins to speed up.
Some shingles will show some nail heads that have popped through the outer layer, this may be a failure, it will fail in this area soon.
Separation or break down of flashing. This, many times, is the first area to fail.
Shingles may have minor cracking and have significant life left.
The test for failure is testing areas, especially stained areas in the attic for moisture. With a GOOD meter. Older homes will usually have stains on the underside of roof sheeting and rafters. In many cases its from a leak many tears ago. That is what the meter tests. Cosmetic stain, or active leak?