Replacing your roofing is a big, expensive job, so do your homework to make sure you get the most out of your investment. Understanding the process and the types of roofing materials available is essential to making the right decisions for your home.

Unfortunately, knowing when to replace your roofing is the home improvement version of Russian roulette -- you'd like to squeeze as much service as possible out of your existing roof before it springs a leak. Once it does, however, it's already too late to avoid additional expensive repairs. Knowing the warning signs of an aging roof can help you time your replacement correctly.

Spotting potential trouble
Once every year, examine your roof. You don't have to get up on top of the roof to check it out; stand on a vantage point where you can see the entire roof -- possibly a neighbor's yard -- and scope it out with a pair of binoculars. Look for signs of wear that include shingles that are cracked, broken, curled and missing; rust spots on flashing; moss and lichen growth; and any discoloration and peeling paint under eaves.

Pay special attention to any branches that are touching or within five feet of your roof. In stiff winds even branches that are several feet from your roof can rub against roofing surfaces, wearing away the protective layers, lifting shingles or even puncturing the roofing materials. Trim back all branches.

Inside the house, look for dark spots on ceilings and walls -- sure signs that moisture is entering your home and that your roofing may have a leak.