What Damages Flat Roof

Roof alligatoring is a phenomenon that occurs as a flat roof age. In general, it’s caused by the sun. The bright UV rays eventually dry out the membrane or coating that tops your flat roof, causing it to crack. The older your roof gets, and the longer you leave alligatoring to its own devices, the worse it will get. Extreme temperature changes, from sunlight, snow, and even internal heating and cooling will cause new cracks to appear and will make existing cracks worse. Blistering and alligatoring are two problems that are common among membrane roofing systems. Alligatoring is a crazed cracking pattern in the roof’s surfacing. It looks a lot like alligator skin, which is where the name comes from. Blistering is a different phenomenon in which bubbles form underneath the roof’s membrane.

What Causes Blistering?

Blistering sometimes results in cracks, but unlike alligatoring, the cracks caused by blisters are usually follow the length of the blister rather than forming a pattern.

Blisters form when there are pockets of air or moisture trapped between layers of your roof’s membrane or between the membrane and the roof deck. As the sun heats the roof, those pockets expand and stretch the membrane. In severe cases, the membrane will actually crack when the pressure becomes too great.

Even if the roof membrane doesn’t crack, blisters are usually a cyclical problem. That is, once they form, the membrane stretches permanently, which allows for even more air or moisture to infiltrate the membrane layers. This causes even more expansion. Each time the sun heats your roof, there is the potential for the blisters to grow a little larger.

At some point, roof alligatoring can become a cause for replacement. If not taken care of quickly, cracks can continue to split down through the roofing material where they will eventually cause water damage. At this point, it’s better to simply replace the roof, rather than do a number of costly and extensive repairs. Here are a few signs that alligatoring has advanced to the point that you should replace your roof:

Water is seeping though the ceiling. If you’re noticing any kind of water damage due to the cracks in your roof, it’s time for a replacement. Ripples and blisters caused from probable saturation under membrane due to leaking.

Alligatoring has spread across the roof. Roof alligatoring usually starts in one spot, and then gradually expands as cracks widen and extend. If you’re noticing that alligator pattern across your entire flat roof, it’s time for a replacement.

Your roofer recommends a replacement. If your roofer is out for a routine inspection and recommends it might be time to replace your roof, don’t wait. The longer it takes you to get that roof replaced, the harder (and more expensive) the job will be.

Remove Debris: Depending on the roof’s location, it may be covered with leaves and other lightweight debris. It can be difficult to spot problems until you can see the roof. Therefore, use a broom or leaf blower to clean the roof. Watch for any debris that may be caught under the roof or protrudes into it. This is a sign that your roof is leaking or will leak soon.

Inspect the edge strip: Climb partway back down the ladder and inspect the edge flushing clear around the roof at eye level. It should be firmly attached to the roof. If pieces are missing or not securely fastened, then the roof may leak.

Look for signs of ponding: Grab the water hose and head back to the top of the roof. If you do not have a water hose that will reach the roof, you could also use a power washer. See if water puddles in some regions of the roof.

Check for weak spots: Walk over the entire roof. If you feel any spots that seem to give way under your weight, then something is causing the roof’s decking to be weak in that spot.

Scrutinize the flages: If you have any pipes or other objects protruding through the flat roof, flanges should surround them to keep the roof from leaking at these points. Be sure that they are all present. They should also be fastened securely to the roof. You may be able to repair very minor problems yourself. If you notice that these pieces are missing, bent or loose, then it is time to call in a professional.

Scan the Drains: If your flat roof has drains designed to remove water, make sure that they are not blocked. Pouring water down them allows you to see if they are working properly. If you notice the drain is not working or seems partially blocked, seek out a professional.

Look for Loose Gravel: Depending on the type of flat roof you have, there should be an even amount of loose gravel across its surface. While you will want to look while you are on top of the roof, check this by walking around your flat roof after a rain. If you see a bunch of it on the ground, then it is a sign that your roof is damaged. Discuss with a professional which type of flat roof meets your needs the best. Generally, flat roofs are built-up roofs, modified bitumen, or rubber membrance roofs, and they each have their advantages and disadvantages.