Various signs can alert you to the need for a roof replacement. Some are easy to spot, while others may require some more investigating:

• Old age: Once your roof reaches 20 to 25 years of age, it starts to deteriorate. When it gets to this point, you should start looking for a replacement. Check your home improvement records to see how old your roof is and what materials it contains. Some roofing materials will require replacements sooner than others.

• Curling and buckling shingles: Sunlight often causes curling and buckling shingles. Check your roof's slopes that get direct sunlight. You may need a replacement if they're showing signs of warping.

• Damaged roof valleys: Your roof valleys are significant parts of your home's structural integrity. They help with drainage, allowing rainwater to flow through them to gutters. When this area starts to break down, leaks become an issue. Examine those valleys for damage. If shingles are missing or broken, you may need a roof replacement.

• Old flashing: Flashing is another crucial part of your roof's drainage system. If you have flashing made of old materials like cement and tar, it may have started breaking down. Use an effective and durable alternative like metal flashing.

• Shingle granules are in your gutters: Old asphalt roofs will lose granules, which then fall into your gutters. A good sign that you need a roof replacement is if your roof's gutters are full of those granules. Dark or inconsistent colors are another signal that your shingles are losing granules.

• Daylight is streaming through the roof: Your attic is a great place to find out if you need a roof replacement. If you notice light streaming in, that's a clear sign you need a roof replacement.

• Sagging roof: One of the more serious signs that you need a roof replacement is a sagging roof, which indicates a structural problem that requires immediate action. There could be a problem with the foundation or attic decking. It's important to get this taken care of before the damage spreads to other parts of the roof.

• Your roof is covered in moss: Moss, mold and fungi can indicate that you may have trapped moisture on your roof. Aside from looking unappealing, this moss can spread and damage your roof. If your roof is covered with moss, it may be time to start looking at replacement options. Dark stains on your roof are also signs of algae — these growths are some of the basic warning signs you need a roof replacement.

Wood roofs are beautiful and often durable. When they're nearing the end of their life, however, it may be challenging to pinpoint when exactly you need a replacement. You can look for a couple of key indicators:

• Dark spots: Wood roofs with dark spots could be evidence of rot. When you spot that warning sign, it's better to get a replacement sooner rather than later.

• Curling shingles: Splitting, curling shingles are a crucial sign of wear on wood roofs.

When you discover signs of age and wear on your roof, you need to address those issues quickly. Your roof protects the rest of your home, so you'll want to ensure it's always in good shape.

Check out pictures of roofs that need to be replaced and compare them with your own roof, talk to your neighbors who are finding replacements and pinpoint warning signs to determine if you need a new roof. Getting started on your new replacement can help you manage any worries about what happens if you don't replace your roof.

If you do need a roofing replacement, that doesn't mean you immediately have to buy new shingles. You should still look at several different factors before getting a new roof.