A typical shingle roof lasts approximately 25-50 years— but only if it is installed correctly. If your previous roofer has used improper materials, there is improper venting of your attic, or many other factors can contribute to a roof that doesn’t last as long as it should.
When roofs— and their partners like gutters and venting— are installed improperly it can cause a number of problems. If you have too little insulation, ice dams can form, which inturn can deform shingles. If you have too little venting in your attic, the heat in the summer can bake the shingles off of the roof, reducing their lifespan considerably. High winds or improperly trimmed trees can also damage shingles.
This is why we partner with Certainteed for our 25-50 year warranties. Only one percent of roofers in the US are select certified this way. This means we do our projects right, backed up by a company more than 100 years old, and even in the unlikely event Home Exteriors of Michigan were to go out of business, your warranty is still as good as the day you bought it.