Let's dive into a few signs that could indicate that it’s time for a replacement.
Have a look inside your attic. Your attic should be sealed with no light piercing through; if you notice a light source, it could be a sign that the structure is shifting. Also, if you notice any stains or streaks then it could be an indication of water leaks.
For older roofing, missing shingles are a common sign, and, over time, the UV rays from the sun and the cycle from hot to cold then back to hot again can wear away the shingles. With the temperature fluctuating and dropping the asphalt can become brittle, and break or crack. Some might even blow clean off due to high winds.
Chimney flashing and flashing in the valleys are two areas that will need repair as soon as possible to prevent damage or leaks.
The purpose of flashing is to keep water from seeping into areas where it tends to collect or where the roofing is more vulnerable. Not attending to your flashing will leave the vulnerable areas unprotected.
Problems with flashing are usually due to age. Gradually, metal flashing can rust and will also need to be replaced. If you live in an area with frigid winters, the freeze and thawing cycle can loosen the flashing slowly over time.
Damaged flashing does not necessarily indicate that you need an entire replacement. In many scenarios, it’s possible to simply replenish the damaged flashing and keep the roofing intact.
Patchy granules on shingles:
Shingles are covered with small granules, these granules usually consist of mineral fibers and minerals, and in some cases, the metal granules manufacturers will mix metal granules to minimize algae growth.
Patchy granules can also be a problem for new roofing as well. If there is nearby a tree or a hanging branch that scrapes against the roofing the granules can be patchy and the asphalt below can be left vulnerable.
If your roofing is approaching 20 years old then it's beginning to cross the threshold of replacement.