A roof is almost more important for a house than a foundation; it gives you shelter. It protects you from the sun and redirects the rain. Without a roof, you don’t have a home. A standard roof will not last forever, though. It will need to be replaced about every 20 years. Depending on the climate and type of weather, some roofs will need to be replaced more often.

The quality of workmanship in installing a new roof matters too. Improperly nailed roof sheathing (the boards that lie under the roofing material) can fail during hurricanes or strong storms, so inspecting the roof for signs of trouble and addressing them with localized repairs could help you get a few more years out of your roof. The National Roofing Contractors Association suggests that you inspect your roof twice a year. If you haven’t replaced your roof since your first child—who is now going off to college—was born, you may want to evaluate it based on the five criteria below.

1. Water Damage or Leakage

If you have to dig out the Tupperware to set under the drips every time it rains, you will need to diagnose the problem. A small leak could turn into a drenching flow more quickly than you would expect. Even if you don’t see water, if you notice water damage on the ceilings or under the roof overhang on the exterior of your home, your roof may need to be repaired or replaced.

2. Changes in Utility Fees

If your heating or cooling bills inexplicably rise and stay high, you may need to replace your roof. Heat rises, and any openings in your roof, however small, act like a sieve to let that air escape. A roof may no longer be doing its job if your heating or cooling unit has to work harder to maintain the temperature within the house.

3. Missing or Damaged Shingles

When the tar seal beneath an asphalt shingle deteriorates, the shingle is more likely to fall off. In addition, asphalt shingles have a sand-like texture for added protection. If that coating wears away (you may begin to see a lot of it build up in your gutters), the shingles can crack and expose the roof beneath them. If the shingles begin to curl, they can easily break off. Blistering shingles are a clear indicator that the roof should be replaced. Water can easily seep below curled or blistered shingles, causing damage.

4. Mold

Mold or rot may indicate a problem with water leakage. Moisture may be more of a problem in humid climates, but any time mold is visible it indicates a moisture problem. Excess moisture trapped between the shingles and sheathing can even attract termites. The presence of termites is a definite reason to replace your roof.

5. Roof Buckling

The moist heat that gets trapped in the attic can cause the roof to buckle, damaging the structure of the roof and causing unnecessary shingle wear. When replacing the roof, your attic ventilation system will be evaluated and can be improved to prevent damage to your new roof.

If you’re planning on selling your home, a new roof is always a positive selling point. If you have had more than one roof inspector recommend that you get a new roof, you should probably pay attention. The longer you wait, the worse the potential damage could become. If your roof needs more than a minor repair, you don’t want to wait until a torrential rain finds its way through the weak spot and into your bedroom. Have it replaced before you really need to.