Common Architectural Shingle Fastening Mistakes That Cause Roof Leaks
What Causes Roof Leaks on Newly Installed Shingle Roofs?
Many roof leaks and shingle failures are caused by improper fastening during installation. When roofing nails are placed too high, too low, overdriven, or underdriven, the shingles may not be secured properly or the nail heads may become exposed. Even though a roof may appear perfectly installed from the7th ground, hidden fastening mistakes can eventually allow water to enter the roof system and cause leaks years later.
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Nails Installed Too High
When roofing nails are placed too high on the shingle, they may only fasten the top shingle and fail to penetrate the shingle beneath it.
Architectural shingles are designed so that nails pass through both layers of shingles, securing them to the roof deck. When nails are installed too high, the lower shingle is not properly fastened.
This can cause the shingles to lift during strong winds and may eventually result in shingles blowing off the roof during storms.
Nails Installed Too Low
Another common installation mistake occurs when roofing nails are placed too low on the shingle.
When nails are installed below the recommended fastening zone, the nail head may not be completely covered by the next shingle above it. This leaves the nail partially or completely exposed to the weather.
Exposed nails can allow water to slowly work its way around the nail head and beneath the shingles. In many cases, the leak does not appear directly below the exposed nail. Instead, water may travel beneath the shingles and roofing underlayment before finally appearing inside the home several feet away.
Overdriven Roofing Nails
Roofing nail guns must also be adjusted properly to drive nails at the correct depth.
If the nail gun pressure is set too high, the nails may become overdriven, causing the nail head to cut through the shingle. This weakens the fastening strength and can allow shingles to loosen over time.
Underdriven Roofing Nails
If nails are underdriven, the nail head may remain slightly raised above the surface of the shingle. As the roof heats up and the shingles begin to seal together, these raised nails can cause nail pops, which can eventually damage the shingles and allow water to enter.
Nails Installed in the Shingle Joint
Another serious installation mistake occurs when roofing nails are installed directly at the point where two shingles meet across the roof.
Architectural shingles are designed so that the nails are placed in a specific fastening area above the joint between the shingles. When nails are installed correctly, they are covered and protected by the overlapping shingle above.
However, when a nail is installed directly at the joint where two shingles meet, the nail head may be left exposed beneath the lifted edge of the shingle.
From the ground, the roof may appear perfectly installed. But if the shingle is lifted at the joint, the nail can often be seen exposed underneath.
This creates a direct entry point for rainwater. As water flows down the roof, it naturally follows the joints between the shingles. When the water encounters an exposed nail at the joint, it can work its way around the nail and into the roof system.
When this mistake occurs repeatedly across a roof, there may be dozens or even hundreds of exposed nails hidden beneath the shingles. Over time, rainwater can travel around these nails and eventually cause leaks inside the home.
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