You might assume you don‚t need to think about installing a new roof until the old one starts leaking, but if you wait that long it will be more expensive. Because by the time you notice the leak, the structural damage will have already occurred.

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. If you‚ve lived there for many years and don‚t know when the roof was last replaced, consider having a roof inspection.

Go outside and look at the roof. 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 is one of the most important parts of your roof because it‚s where snow and rain flow to the gutters.

When you clean your gutters do you find a lot of asphalt granules in the gutter? That‚s a sign the asphalt shingles are starting to breaking down.

Do you see cracked, curled or misshapen shingles? As shingles age, they begin to deteriorate. Check to see if all of the tabs are intact.

Go up in the attic, preferably during or immediately after a good rain, and look for evidence of leaks or moisture. Also check to see if there‚s any daylight streaming through the roof boards.