The roofing materials protect your home for the elements and are very important. If you have major issues due to material failure or improper installation this can destroy your home by allow moisture into the home.The roof covering materials need regular maintenance. Debris will need to be removed from the roof surface which is a minor problem if maintained, but can cause materials to deteriorate sooner than life expectancy so it's important to remove from the roof.I would have my roof inspected after any bad storms or around 10 years,because roof jacks can fail allowing moisture to enter. During the home inspection if it is safe to walk i will walk the roof area to get a much better view. Some common defects are improper installation, improper flashing or missing flashing, lifting flashing that will allow wind driven rains to entry the structure, missing shingles, damaged shingles, missing H clips, mastic repairs around fireplace, roof jack flashing, and shingles. Mastic repairs are not a permanent solution and will need monitored. It is allows a better practice to replace flashing and shingles for a more permanent repair.Most defects are serious at the roof, because if not repaired it allows for moisture to enter into the structure and moisture can destroy areas of your home. So any defects noted in the home inspection report by your home inspector should be repaired.

What's the roof look like

If the roof of the home looks like this at the home your about to buy than the roof is failing you and your family. This roof needs replaced and that's what I recommended in the report. Replacing a roof is a very expensive project make sure you know the condition of the roof before it fails you. Once the roof fails it can cause damage at many areas of the interior, structure damage costing you much more than just a new roof being repaired. Have a quality home inspector inspect your roof and don't get caught with extra expenses.

Raised shingles are an indication of lifting nails. They can damaged the shingle and cause a leak.

Raised shingles are an indication of lifting nails. They can damaged the shingle and cause a leak.

Mastic around roof jacks , chimneys, or at shingles is a good indication of a PREVIOUS roof leak. This type of repair is not a permanent solution. 

Mastic around roof jacks , chimneys, or at shingles is a good indication of a PREVIOUS roof leak. This type of repair is not a permanent solution. 

Example of a nail lifting.

Example of a nail lifting.