A home’s roof is the first line of defense against rain, snow, cold air and harsh weather.

To keep it in top shape, experts recommend performing a roof inspection twice a year.

Look for missing shingles or deteriorated flashing — the metal that seals bends and joints on skylights and chimneys.

More than 90 percent of roof damage will occur in these two areas and catching it early can be key to preventing bigger and more costly problems.

Try these additional tips:

When to inspect — Check your roof in spring after severe weather hits, and then again in winter, before the worst weather sets in.

What to look for — Examine the roof edge for wind damage or damage caused by driving rain and ice dams.

The damage occurs when water freezes and backs up under the roofing system.

In addition, inspect for signs of mold, algae and mildew growth. Signs include dark spots and discoloration on the shingles.

Roof maintenance — Leaves, sticks and other debris can cause water to back up and flow under a roof, so be sure to clean out your gutters and roof drains regularly.

Be sure to also check that all gutters are securely fastened to the house and that downspouts are pointing away from your home.

If you spot damage — If your inspection reveals roof damage, be sure to work with professional roof contractors who are bonded, insured and use quality materials.

They can keep you from having to spend money on costly future repairs and prolong the life of your roof.