Roof Leaks: The Most Common Causes

Roof leaks are a bummer but can happen to any roof. It is important to take immediate action to avoid any future damage to your home once you notice any leaks.  There are quite a few things that can cause these roof leaks. Here are some of the most common.


Roofing materials deteriorate with age. Therefore, they become less effective at keeping water out. Temperature fluctuations and weather may cause roofing materials to become brittle and crack. Exposure to direct sunlight can melt the tar that seals shingles together. Proper maintenance can help prevent these issues, but some roofs just need to be replaced. 

Roof Vents

Roof vents are the things that look like small pipes sticking out of the top of your roof. They are used to expel excess moisture from the inside of the house. It is important for any penetration through the roof to be sealed properly to prevent leaks. The flashing used to seal the roof vents can break or the roof can decay. 

Dark spots and mustiness are the best indicator that you have leaks in your roof vents.  Inspect the gaskets around the vent pipes for cracks or gaps and check for missing nails. Plastic vents may crack after years of exposure to the weather. 


If the roof slope is too shallow, wind can lift the shingles and drive rain underneath them. The International Building Code states that the roof slope must be at least 2:12 for installation of asphalt shingles. If the slope is between 2:12 and 4:12, there must be a double layer of underlay materials. Ensure that your roofing materials are appropriate for the roof pitch and are installed properly. 


Buildup of debris can trap water against the roof and allow it to slowly seep in. It is important to keep the roof clear to allow water to run off quickly. Trimming overhanging tree branches makes it easier to keep your roof free of debris. 


Flashings are thin pieces of metal that are installed under shingles and on the joints of your roof. It helps to seal roof transitions where large amounts of water run down. They place flashing where the roof joins a dormer, which is where a chimney penetrates the roof and around the edges of skylights. If exposed, they will look like long runs of sheet metal. If concealed, they will have a rubberized coating on top. 

Flashing sections may slide out-of-place if nails are missing and caulk may dry and crack. The tar used to seal flashing together can also corrode. Look for large cracks in your flashing to see if it is broken. 

To fix it, find the source of the leak. Pry up the nails used to secure the old flashing and lift any shingles out of the way. Remove the cracked segment and put a new run of flashing in its place. Fasten it in the same pattern as your old piece using roofing nails. Next, apply a coat of roofing sealant to the nail heads. 


Valleys are the area where two planes of a roof come together. This area is usually sloped, so if the valleys aren’t sealed properly, rainwater can get inside as it runs down the roof. This happens for a variety of reasons, such as sealing not being done properly in the first place, sealings being cracked, or erosion due to rain and ice.

It is best to call a roofer for this type of problem.

Gutter Backup

Gutters that are clogged with leaves or other debris can slow the water flowing off the roof, giving it time to soak through. When a blockage forms, the water stops and pools in one area of the roof. This gives it an opportunity to seep through the cracks. Therefore, it is so important to keep your gutters cleaned at all times. 

You can spot clogged gutters pretty easily with the naked eye. If you don’t see any problems, but notice the lack of water trickling out of a downspout during a storm, your gutters may have a clog in them. 

Gutter covers can help keep gutters clear of debris. This ensures water flows freely and quickly off the roof. Regular gutter cleaning, usually in the spring and fall, also helps to prevent this issue. 

Excess Moisture

Draining upper roof gutters directly onto a lower roof can lead to the lower roof becoming over-saturated. This causes leaks. Extend the downspout to the next gutter or down to the ground instead. 

Condensation can get into your attic, as well. If your attic shows signs of mold or mildew, or smells musty, water may have gotten inside. Because the attic is at the uppermost part of your home, indoor and outdoor temperatures meet in the middle. When those temperatures clash, condensation and moisture follow. 

If you notice mold growth, treat it right away. Make sure all of your roof vents are clear from the interior end and install a large ventilation system to prevent condensation from setting in. 

Missing or Broken Shingles

Strong winds and heavy rains can damage or rip shingles from the roof. This may expose an area of the roof that you cannot see. 

Shingles are usually easy to see when damaged or missing. Climb a ladder to inspect hidden areas and check for missing shingles. 

You should replace any missing or broken shingles as soon as possible to avoid problems. 

Ice Dams

An ice dam is a ridge of ice that forms at the edge of a roof and prevents water from draining off. The combined weight of the ice itself can damage the roof. Water sitting on the roof’s surface damages it as well. An ice dam forms when the heat in your attic is above freezing. This causes the snowfall on your roof to melt. The water will then run between the roof’s surface and the snow and will re-freeze into ice once it hits the roof’s exterior edge. 

Invest in a roof rake to remove the snow from the roof edge. If you see an ice dam forming, treat it with an ice melt product. 

Roof leaks are a sign of bigger damage or damage to come to your roof. If you notice any leaks, take immediate action and call us at 636-699-0449.