It is best to hire someone who is trained properly to assess the condition of a roof? However, you can take the binocular and check few things to see if your roof needs a replacement. You can examine if the shingles are curled or buckled in the edges and tried to located bald spots where granules are missing. It may not be easy to locate the missing granules. Take a look in your gutters to see if there is excessive amount of granules. Shingles lose more granules toward the end of their life cycle. Inconsistency of a roof color is another sign that granules are missing on the roof. You can also check chimney flashing is cracked.