Signs of a Bad Roofing Job & How to Avoid It (Visual and Structural Problems)

Home remodeling projects can range from small to large, and a roofing job is definitely one of the more extensive and costly projects you can undertake. Depending on the severity of the weather in your area, you can generally count on your roof lasting two decades or longer. Unfortunately, not all roofing contractors install roofing systems correctly. When this happens, your roof will not perform as advertised.

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Let’s take a look at ways to determine if your roof was installed correctly and how to avoid getting into a situation where you choose the wrong contractor.

How to verify if your roof is installed properly

  • Take a quick visual roof inspection

    A quick, visual inspection from the ground should reveal any uniformity issues, which will include the roof aging differently in some sections than in others. Also, look for missing or cracked shingles. The presence of stains often indicates leakage, which could be a simple fix if it’s an isolated issue.

  • Inspect for structural roofing problems

    Finding structure problems on the roof is not as easy as seeing the outer portions of the roof that might have issues. The structural elements include roof decking, underlayment, drip edges and flashing. Structural problems will lead to premature leakage and other issues, which is why a thorough inspection is advised.

The appearance test: common visual signs of a bad roofing job

It’s actually quite easy to spot a poorly installed roof – you simply have to look up from the ground. Unfortunately, these signs usually don’t present themselves immediately, which means a new roof that is improperly installed might look perfectly fine at first, but after a year or so, the imperfections begin to stick out like a sore thumb.

The roof is not uniform in appearance

If your roof looks great on one side but completely different (poor) on the other, the job wasn’t done correctly. This could include mismatched shingles, which means the contractor could have cut corners to save on time and/or money, resulting in a subpar job.

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Here are a few things to look for in a uniform appearance:

  • Do you notice sagging rooflines?

    These are fairly easy to spot, as rooflines should all be as straight as an arrow. If you see a dip or a curve, the roof has a problem and it’s usually within the framing of the roof or could be associated with roof decking that should have been replaced.

  • Are some asphalt shingles different in color?

    If you spot shingles that are different in color, it’s usually an indication that the roofer ran out of your preferred choice and instead of ordering more they used whatever they had on hand at the time.

  • Is one section of your roof different from the rest in terms of material type?

    Again, this is an indication that your roofer ran out of your preferred material. Quality contractors never skimp on materials and will be sure to order the right type and the right amount so your roof will be installed on time and as promised.

The roof is missing shingles or has damaged shingles

The decision to replace a roof is often associated with wearing, damaged and/or missing shingles. A new roof with such issues is a sure sign that the contractor did an improper job of installing the new roof. All shingles should be new and pristine, not recycled or reused.

Reusing old flashing material

Flashing is the thin piece of sheet metal installed on a roof to prevent water leaking into the home at various angles and joints along the roof. Just because the roof wasn’t leaking before the new roof was installed doesn’t mean the flashing should be reused. While there is no code violation associated with reusing old flashing, quality roofing contractors know that the nails used installing the new roof won’t always go through the old holes in the reused flashing. The only way to ensure you’re not going to incur leakage is to replace the old flashing with new flashing.

Roofing materials were not attached correctly

One of the more common roofing mistakes is related to attaching materials with the wrong nail type, or the right amount of materials weren’t used, which will eventually lead to damage. This type of damage is completely preventable, but choosing the wrong contractor usually means that materials will be attached incorrectly because they don’t follow local and/or state building codes.

Stains on the roof

Stains, usually dark in color, are a sign that leakage is occurring. Be sure the check your attic, as the leakage, if severe enough, will show through to your surface of the attic. If the leak is isolated, it can usually be repaired. If you notice numerous stains, it’s a sign that there are more extensive issues that could require a roof replacement, including replacing the roof decking.


A properly installed roof will wear in a uniform fashion. In an improperly installed roof situation, you’ll see different colored shingles, missing drip edges or vents that have been reused instead of replaced. You’ll also notice a difference in how some sections of the roof age compared to other sections. Frequent visual inspections will help you notice issues before they become major hassles.

Structural problems of a bad roofing job you should know about

There are several factors that impact the integrity of the roof. Using the wrong materials will lead to a prematurely aging roof, which means leaks will occur long before they can usually be expected. The following are some of the more common structural problems that occur in improperly installed roofs.

roofing problems

Wrong nails or improper nailing techniques are used

To ensure the roof won’t leak, the right type of nails must be used. This includes correct type, grade and size of nails, which will differ depending on what materials they’re being used. It’s also important that the nails be driven into the materials correctly. For example, an under driven nail will not penetrate through to the deck, increasing the risk of leakage or missing shingles. An over driven nail will cut into the shingle, increasing the risk of leaks. A nail that is driven in crook will also increase the likelihood of damaged shingles and leaks.

Hardware mistakes

The roof is about more than just shingles – it requires the right hardware, which includes flashing, vents, drip edges, nails, underlayment and decking. They all work in concert to ensure a healthy, uniform, leak-proof roofing system. Also, different hardware requires different nail types, which is a vital component in a properly installed roof. Making hardware mistakes is a sure sign that the roofing contractor is off the mark and needs to be following best practices, codes and material installation specifications.

The roof is missing a drip edge

Drip edges are important, because they keep the water moving in the right direction – toward your gutters, which carry the water away from the house. Drip edges are made of galvanized steel and are installed above the underlayment but below the singles at the edges of your roof. When you experience high winds, the drip edge will keep the water from moving up under your roof. A missing drip edge will result in mold and/or rot in your roof decking or within your home. It will also cause staining, soil erosion around your foundation and a potential for a flooded basement.

There is missing underlayment

Underlayment plays a big part in your roofing system, as it is a felt-like material installed below your shingles and above your roof decking. It’s an added layer of protection, so if it’s missing, you could experience premature aging of the roof and will most likely experience leaking. By some accounts, missing underlayment will make a roof that is only 10 years old appear to be at least four to five times its actual age.

Roofer mistakes: avoid a bad roofing job before it happens

With due diligence, you can avoid a bad roofing installation. Make sure your contractor performs a thorough inspection of the roof before they install the new one. The following are some common mistakes they make, which can be completely avoided:

  • The roofer didn’t check the roof decking

    The roof decking is essentially the foundation of your roof, upon which all the other pieces of the roofing system are attached. Over time, roof decking will become compromised by the elements and need to be replaced. An experienced roofing contractor will check the integrity of the decking and make repairs or complete replacement as needed.

  • The roofer didn’t replace the old vents with new ones

    Roof vents are part of what helps your home to “breathe.” Circulation throughout the home prevents moisture from collecting, which when allowed to happen will result in mold and rot. Some vents are there to release exhaust, such as from a hot water heater or gas from sewer lines. Don’t allow your roofer to reuse old roof vents, because just like your old flashing, the nails driven into the roof vents might not line up with the old holes, which can lead to leaks, and that’s why replacing old vents with new ones is a requirement.

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How to avoid unscrupulous roofing contractors

You have options in which the contractor replaces your roof. While many will be reputable, some will cut corners and do a poor job. It’s important to do your research and find the one that will do a quality job for you.

Here are the things to look for in a roofing contractor:

  • License and registration

    Roofers are required to have a roofing license issued by the Department of Professional Regulation.

  • Experience

    There are many different types of roofing materials, and you want your contractor to have ample experience with all of them.

  • Insurance

    Make sure your contractor has insurance with property protection, general business liability and clearly stated limit and minimum coverage.

  • Communication

    It’s important in any home remodeling project that the contractor be a clear communicator who updates you frequently with the status of the job.

  • Reputation

    Bad reputations are earned, as are good ones. Check around and see what former clients have to say about your prospective contractor’s reputation.

Be sure to ask for references. You can even ask your friends and neighbors who they chose to replace their roof and follow up with those contractors to ensure they have the above qualifications.

Do you suspect signs of a bad roofing job?

At VIS Exterior, we’ve assisted many clients who have had a bad experience with their previous contractor. You often get what you pay for, and if you choose the least expensive roofer, they probably cut many corners to make their profit. Unfortunately, you’re left with a roof that won’t last. VIS can fix that for you. If you suspect a bad roofing job, we’ll do a thorough inspection and get to the bottom of any issue that might come up. Contact us today and let’s schedule an appointment.

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Val Slajus
Owner / Author
Val Slajus

My journey began with a passion for home improvement, and I established VIS Exterior because I firmly believe that everyone deserves to live in a beautiful home. With years of experience in the roofing and siding craft, I'm dedicated to helping you enhance the protection and aesthetics of your home. Through this blog, I'm excited to share my knowledge and insights, empowering you to make informed decisions when planning your next exterior renovation project.

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