When your roof has caved in or a good amount of shingles have blown away due to a recent storm, you typically know it's time to call a roofing contractor and get the roof repaired or replaced. However, you don't want to wait until the signs that you need a new roof or some repair work are that obvious. Note when you might consider calling a roofing contractor to at least evaluate your current roof, and then discuss with them the possibility of repairs or a new roof altogether.

1. Bald shingles

The shingles on your roof may be in place but if they're bald, meaning the top surface is now smooth rather than rough, they typically need replacing. This balding happens from exposure to the elements; rain, snow and high winds can cause abrasion to the shingles and wear them down so they're smooth. This is not a problem to ignore; when shingles are bald, they are not protecting your home from outside temperatures as well, and they may be allowing your inside heating and cooling to escape. In this case, they usually need to be replaced.

2. Sagging

If you look at your home from across the street and you can see that your roof is sagging, you need to speak with a roofing contractor right away. Sagging is typically a structural issue, but it can be caused by water leaks that have softened the building materials under the roof. You may want to replace the roof beams and other such materials and then also the roof itself. It might even be good to update your home to a metal roof; the long, single pieces of metal might offer more protection against water damage than shingles. Metal is also more lightweight than many other roofing materials, so if the structural damage is caused by weight issues with your roof, metal might be a good choice for a replacement. 

3. Mold or algae growth

In some cases, mold or algae can be a cosmetic issue and you can have the roof cleaned to remove it. However, if the mold or algae is excessive, this can mean that the roofing shingles are pulling away from the flashing or roofing paper and allowing water to collect underneath their surface. Mold then grows, and this can continue to push the shingles away from the roof. In turn, they may have come loose and are at risk of falling off, so it's good to have them replaced as needed.