5 Most Likely Reasons Why Your Roof Is Leaking

By Juno Construction

The roofing system may seem complex, but there are specific areas that consistently leak when they are not waterproofed correctly. Juno Construction is an expert when it comes to waterproofing and we know where to look when calls come in for leaky roofs.

Listed below are the top 5 areas that we find leaks

1) Valleys

One roof element especially prone to leaks are the valleys where two different elevations meet. A roof valley, as shown in this image collects rain and moisture and moving it down and off the roof. This is a vulnerable area for leaks causing serious damage if the valley materials, underlayment, and surrounding elements are not installed correctly.
*This is an example of one problematic installation. NEVER install a plumbing boot in the valley.

2) Chimneys

Chimney leaks are one of the most common roof leaks. There are several installation errors that can cause a chimney to leak over time. One of the biggest issues Juno Construction sees is the failure to install a chimney saddle. Chimney saddles help move water away from the base of the chimney. Without one, water can pool around the base and eventually work its way behind the underlayment. 

The first picture below shows a chimney that had been leaking due to an absent chimney saddle which Juno Construction is now installing. A second installation failure causing chimney moisture intrusion is improper ice and water shield prep. If ice and water shield is not wrapped up the side of a chimney before the flashing installation, leaks can occur. 

The water staining on the second picture below shows how vital this waterproofing detail is.

3) Roof Openings

Any opening on your roof that prevents roof felting from being continuous is susceptible to leakage. This could be anything from plumbing boots, bathroom vents, furnace vents, skylights, radon and exhaust vents. 

Typically, the culprit for these leaks is reverse lap of the felts allowing water to flow under the shingles and compromising other roof elements’ performance. A good roofer, Juno Construction understands that shingles alone will not prevent water from entering a building. 

We know that water will eventually end up behind the shingles and why we invest energy into correct felting procedures. When felts are installed correctly, they will shed water off the roof. The following videos explain what reverse lap is on a basic level.


4) Ridge Vent

Ridge vent is an exhaust system that sits at the peak of a roof. It is becoming more popular for aesthetic reasons, but in reality, can lead to moisture intrusion. Juno Construction does not like to use ridge vent for 2 main reasons.


  1. Roofs with low slopes are most susceptible to leakage because wind driven rains can actually blow water up the roof and under the ridge vent.
  2. For ridge vent to be effective, it must have an equal amount of material on each side of the ridge and wide enough down each side of the peak to prevent water from getting underneath it. However, it is not always manufactured to meet either of these criteria, so water will often end up in the attic.
Ridge vent leak

5) Roof to Wall Intersections

Roof-to-wall intersections are areas where water travels on a roof. Because this area is susceptible to leaks, building codes exist to prevent moisture intrusion.  

Midwest building code dictates that ice and water shield must be run up the side of walls before flashing can be installed. This is because ice and water shield prevent water from leaking into your home while flashing is simply a “last defense”. 

Many roofers fail to install ice and water shield properly because it involves removing any existing siding. This adds significant time and labor to a job, so often times, short cuts are taken. Juno Construction takes the time and care to properly install the required elements.

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