Here are some tips to help decide whether the time has come to install a new roof:
How old is the existing roof? If installed properly and with good materials, an asphalt shingle roof should last 20 to 25 years, sometimes longer. It also depends on how many shingle layers you have and if it was properly ventilated. Are the shingle lines still straight or can you see sags or other irregularities? A sag would indicate that the sheathing underneath is rotting. Pay close attention to the valleys, which are one of the most important part of your roof because it's where snow and rain flow to the gutters