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The 5 Most Common Causes of Roof Leaks

May , 2023 | 5 min. read

By David Toth

home with damaged chimney and roof

The realization that you have a roof leak tends to drop like a stone in your stomach.  Whether it's hidden behind your walls causing a slow creeping drip, or looks something like a bad replica of Niagra Falls, roof leaks are a pest. At some point in life, every homeowner experiences this dreaded feeling and learns that a roof leak couldn’t be anything less than a nightmare.

Regardless of the cause, roof leaks can lead to much bigger problems than just having to run for a bucket every time it rains. 

RoofCrafters has been repairing roof leaks since 1994, and we know that if a leak is neglected, what could've been a tiny solution can lead to bigger problems in a short period of time if not taken care of promptly. Not only can the water intrusion lead to structural damage, but it can also cause mold and mildew to spread throughout the house. Then there are other risks like water finding its way to electrical wiring and becoming a fire hazard.

Needless to say, roof leaks can be a cause of far greater concern than just a few drops of rainwater. Therefore, it is important that homeowners should always be on the lookout for the common causes of roof leaks. Finding the cause can help you determine if a quick fix would do or if you are in need of a roof replacement. So, without further ado, here are 5 common causes of roof leaks that you should nip in the bud before it's too late! 

1. Cracked Flashing


Flashing is the part of your roof that creates a water-resistant barrier. They are typically made of thin pieces of metal that are installed under shingles and on the joints of a roof. If they are exposed, they appear like long runs of sheet metal. On the other hand, if concealed, they have a rubberized coating on top. Broken flashing will feature large cracks.

rusted flashing at a brick chimney coming through a metal roof

Roofers usually use tar to seal the flashing together and to fill in the cracks, but over time, it can corrode, causing cracks or gaps in the flashing. Oftentimes, strong winds and rains cause the flashing to crack.

2. Broken Shingles


Shingles are the outer layer of a roof structure, used as a cover for the underlay which stands as a barrier to water intrusion. If your roof has a missing shingle, simply taking a look at your roof will indicate it. This is also the best tip for preventing further damage. A damaged or missing shingle exposes your roof to external elements. It also causes air to find its way into the ventilation part of your roof.

missing shingles

You might have noticed after a night of heavy storms, a few shingles or their pieces scattered across your yard. Bad weather conditions, especially thunderstorms and hurricanes can cause these materials to come loose and fall off your roof.

3. Poor Ventilation


Improper venting can be another common cause of roof leaks, and this could be in two different ways:

  1. Excess condensation in your attic
  2. Leaks in the vents themselvesdamaged vent-1

If your roof doesn’t have enough ventilation, it is likely that moisture will build up in your attic. This means that it will lead to the growth of mold and mildew throughout the structure as it has nowhere else to go but to stay in the attic.

As a result, this will not only weaken your roof structure but will cause roof leaks over time. Not to mention the damage from the condensation build-up. Similarly, vents that have not been sealed properly can also cause roof leaks. This could be cracks or gaps around the vent pipes or gaskets.

4. Shallow Roof Slope


Shallow roof slopes allow wind to lift shingles, which can cause roof leaks during rains. Generally, the measurement of a roof slope is taken as a ratio of its vertical rise, in inches, to a horizontal distance of 12 inches.


As a standard rule, the roof slope has to be at least 2:12 in order to get asphalt shingles. So, if the slope measurement falls between the ratios of 2:12 and 4:12, a double layer of underlay material should be used. Aside from the measurement, you must also ensure that your roofing materials are of high quality and are appropriately installed by a professional roofing contractor.

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5. Ice Dam Buildup


A ridge of ice that forms at the edge of a roof is usually referred to as an ice dam. It prevents the water or melting snow from draining off the roof. The accumulated water, as well as the weight of the ice itself, can damage the roof. Moreover, the water sitting on the roof’s surface can also lead to damage over time.  

Sometimes, the heat coming off your house causes some of the snow to melt on the roof even when the temperature outside is below freezing. As a result, the melted water flows between the roof’s surface and the snow and eventually refreezes back into ice once it reaches the roof’s exterior edge. If you live in a region where ice and water tend to overstay their welcome on your roof, find out if you need a simple repair or complete replacement by taking the quiz below.

Image call to action, take the repair or replace quiz

Do I Need a Roof Leak Repair?


As you now know, roof leaks damage the structure and cause mold and mildew to spread throughout your house. Not to mention the more serious dangers as a result of water getting to the electrical wiring. Thus, your best line of defense is to be always looking out for the causes of roof leaks so that you can take prompt action to mitigate the risks.

If you suspect or have a roof leak that needs inspection and repair, it's time to take the quiz above and give your local roofing contractor a call. At RoofCrafters, our specialists offer professional and affordable roofing services. So, whether your roof needs a simple fix or a roof replacement, we can get your roof back on track. Drop us a line on our contact page anytime, anywhere. 

In the meantime, if you believe you're experiencing a roof leak and need help in determining what attention your roof needs, check out our article, "Roof Repair vs Roof Replacement" so that you can better understand what steps to take next. 

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David Toth

My name is David Toth and I am the lead estimator in North Florida with RoofCrafters Roofing. Originally from New Brunswick, I have called Florida home for the past 47 years. I enjoy cooking along with traveling to different historical areas in Florida when I have free time.