As home inspectors in Western Montana, we've walked thousands of roofs over the years. In those years, we've gained an understanding of the types of findings homebuyers should anticipate when it comes to roofing systems. In this article, we are going to share what we consider to be the top 10 most common roof inspection findings. However, the term "common" in this context should not be taken to mean something to be ignored. Many of these findings warrant immediate correction in order to avoid more significant issues in the future.

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1. Exposed Fasteners

This is one of the most common roof defects we document. On asphalt roofs, it often appears as exposed nail heads that were never sealed properly or the sealant has deteriorated. On metal roofing systems, it’s commonly caused by fasteners backing out over time due to thermal expansion and contraction.

The concern is fairly straightforward: exposed fasteners create potential moisture entry points. Sometimes the repair is simple maintenance. Other times, widespread fastener issues can indicate improper installation practices and may warrant further investigation.

The important thing for buyers to understand is that seeing a few exposed fasteners is extremely common. It’s not unusual, and it’s rarely a reason to panic. It is, however, something that should be addressed before it becomes a leak.

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2. Missing Kick-Out Flashing

This is one of the most important flashing details on a home, and it’s missing surprisingly often.

Kick-out flashing (or diverter flashing) is installed where a roof edge meets a vertical wall. Its job is to direct water away from the siding and into the gutter system. Without it, water can repeatedly run behind the siding, leading to hidden rot, moisture intrusion, and structural deterioration over time.

Modern building codes require kick-out flashing, but many older homes were built before the requirement became common practice. Even some newer homes are missing it.

For buyers, this is a good example of a defect that may not look dramatic from the ground but can create significant concealed damage if ignored long enough.

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3. Deteriorated Vent Boots

In many cases, the plumbing vent boots will fail before the shingles themselves.

These rubber or neoprene flashings surround plumbing vents that penetrate the roof. In Montana’s climate, UV exposure and temperature swings eventually cause the material to crack, split, or deteriorate.

The good news is that vent boot replacement is typically considered routine roof maintenance. The bad news is that neglected vent boots are one of the most common sources of roof leaks we encounter.

Buyers should understand that replacing a few vent boots on an aging roof is fairly normal and does not necessarily mean the entire roof has failed.

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4. Improperly Installed Chimney Flashing

Chimneys are one of the most leak-prone areas on a roof, largely because proper flashing installation takes skill and time.

A common issue we see is counter flashing that was never properly cut into the masonry. Instead, installers rely heavily on sealant or caulking to keep water out. The problem is that sealants eventually fail, especially in climates with significant freeze-thaw cycling.

Proper chimney flashing should include metal step-flashing integrated into the roofing material and counter-flashing embedded into the chimney mortar joints. Unfortunately, many installations cut corners.

This is one of those defects that buyers should take seriously because water intrusion around chimneys can remain hidden for long periods before interior signs appear.

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5. Asphalt Shingles Installed on Low-Slope Roofs

Asphalt shingles are not designed for every roof pitch.

Most manufacturers and building codes require a minimum slope of 2:12 for asphalt shingles, with additional underlayment requirements often needed between 2:12 and 4:12. Below those slopes, water drains too slowly, increasing the risk of moisture intrusion.

In Western Montana, we occasionally see shingles installed on roof sections that are simply too flat for the material. Sometimes this was done to save money compared to membrane roofing systems.

This doesn’t always mean the roof is actively leaking today, but it does mean the roofing material may not perform as intended long term.

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6. Ice Damming

Ice damming is incredibly common in Montana, but many homeowners misunderstand the root cause.

The issue usually isn’t the roofing material itself. Ice dams are primarily an energy-loss and ventilation problem. Warm air escaping into the attic melts snow on the roof surface. The meltwater then refreezes near colder roof edges, creating ice buildup that can force water beneath shingles.

In other words, the roof is often revealing a problem occurring inside the building envelope.

Improving attic insulation, air sealing, and ventilation is often more important than simply replacing roofing materials. Buyers should understand that a brand-new roof can still experience ice damming if the underlying energy issues are not corrected.

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7. Improper Ridge Cap Material

This is especially common on architectural shingle roofs.

Instead of using manufactured ridge cap shingles designed to bend and protect the roof peak, installers sometimes cut standard three-tab or flat architectural shingles and use them as ridge material. Over time, these improvised ridge caps tend to crack, lift, or deteriorate prematurely.

It’s a relatively common workmanship issue and often more of a maintenance concern than a catastrophic defect, but it can shorten the life of the roof system and increase the likelihood of wind or moisture damage.

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8. Multiple Layers of Roofing

Finding multiple layers of roofing is common on older homes.

Building standards generally allow a maximum of two roofing layers, provided the underlying roof structure can support the load and the existing roof surface is suitable for re-covering. While multiple layers are not automatically considered defective, they do come with tradeoffs.

Additional roofing layers add weight, make leak detection more difficult, trap heat, and can reduce the lifespan of new materials installed above them. They can also hide underlying sheathing damage.

For buyers, this is often more of a “future planning” consideration than an immediate repair item. A roof with two layers may still perform adequately today, but replacement costs are often higher when tear-off eventually becomes necessary.

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9. Advanced Granular Loss

Granular loss is one of the clearest signs that an asphalt roof is aging.

The granules on asphalt shingles help protect the material from UV degradation and weather exposure. As shingles age, those granules gradually wear away. Eventually, the underlying asphalt and/or fiberglass becomes exposed and more vulnerable to deterioration.

Some granular loss is expected over time. Excessive or widespread granular loss, however, often indicates the roof is nearing the end of its expected service life.

This is one of the most common conditions buyers encounter during inspections, especially on homes with roofs approaching 15–25 years old.

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10. Leaking Skylights

Sooner or later, skylights leak. That may sound blunt, but it’s often true.

Skylights are essentially intentional openings cut into a roofing system. Even when installed correctly, they introduce additional flashing transitions and seal points that become vulnerable over time.

Some skylight leaks originate from failed glazing seals. Others stem from deteriorated flashing, roof aging, condensation issues, or improper installation details.

That doesn’t mean skylights are inherently bad, but buyers should understand that they are statistically one of the more leak-prone components on many roofs.

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