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Is It Ok To Install A Metal Roof Over Shingles

Metal Roofs Are No Noisier Than Asphalt Roofing

Standing-Seam Metal-Shingled Roof Installation

Although it’s a common misconception that metal roofs are noisy when rain or hail falls on them, the reality is that when properly installed, metal roofing is no noisier than any other type. Metal roofing is typically installed over a solid substrate. Additionally, the attic and insulation provide a sound barrier. From interior living spaces, inhabitants rarely notice any increase in sound levels when a metal roof is installed.

Step : Lay Down Roofing Felt Over The Entire Roof

Your goal with the roofing felt is to make sure everything is as straight and as square as possible. To do this, you might need to put wood strips in place as well.

Also, keep in mind that flashing will need to be installed for dormers, chimneys or any possible seam where you are especially concerned about water. The key here is that you are aiming for a very square, symmetrical look without the risk of water damage later.

Severe Hail Can Ruin Metal Roofing

Although metal roofs are considerably more durable and maintenance-free than asphalt shingles and other forms of roofing, they are not indestructible. There is one weather condition in particular that bodes ill for metal roofing: large hail. Aluminum and copper, in particular, can be susceptible to denting when hailstones approach golf-ball size. Steel is harder and fares better in hailstorms, but if you live in a region where such catastrophic hail can occur, be aware of this when considering metal. Pea-sized or even dime-sized hail is rarely a problem, but hailstones larger than this have been known to ruin metal roofs.

Then again, large hail can also destroy an asphalt shingle roof, so if you make sure to have good homeowner’s insurance that covers such storm damage, there is no reason not to install metal roofing.

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Metal Roof Over Shingles Problems

While installing metal roofing over shingles is a convenient and cost-saving means of adding a new metal roof, it isnt without its pitfalls. In this section, well cover some of the problems youll encounter with this type of metal roof installation.

Roof sheathing is covered typically, the old shingles are removed before installing a new roof. This gives the homeowner a chance to inspect the roofs deckings for any problems such as rot to determine if structural repairs need to be made before proceeding with a new roof installation.

There is no thorough way to conduct this inspection when the roof is covered, which may lead to unwelcome surprises later if there are structural problems that are hidden beneath the shingles.

Complicates future roof repairs If there is a roof leak in the asphalt shingles, adding a metal roof will provide a patch for those leaks. However, if there is a leak in the metal roofing, water will run between the two roofs until it reaches the original leak, then leaks through the roof. This scenario can make the leak difficult to diagnose and fix.

Condensation The space between the original asphalt roof and the metal roof wont be airtight. This means damp air can get in between these two layers, causing condensation to form, which can lead to mold growth or rot.

What Is The Best Underlayment For Metal Roof


The traditional and most common material used for roof underlayment on a steep-slope metal roof is non-perforated, asphalt-impregnated felt underlayment. There are several types of felt underlayment including both organic reinforced and inorganic reinforced.

Does metal roof need drip edge?

A drip edge is a metal strip which extends beyond other parts of a roof and directs rainwater off the roof away from the fascia and into the gutter. This is important because a badly positioned drip edgeor no drip edge at all can cause overflowing of gutters, over front or back.

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No Longer A Novelty Metal Roofing Has Many Advantages

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The Spruce / Christopher Lee Foto

Metal roofing has now entered the mainstream and has become a viable option for nearly all homes, except those with very flat roof pitches. Nor do all metal roofs scream “metal.” There are now shingle-style metal roofing products that are almost indistinguishable from traditional asphalt shingle roofs. If you are wondering about the merits of metal roofing, here are 12 things to know.

Metal Roofing Installed Over Shingles

According to Union Corrugating, most roof types simply weigh too much to be installed over top of one another without adding additional structural support to the roof. Roofs are designed to support a predetermined amount of weight and the installation of subsequent layers of heavy roofing materials such as asphalt roofing shingles can cause structural damage. In these cases, removing the old asphalt roofing shingles is usually recommended, but this creates a large amount of landfill waste. In fact, asphalt roofing shingles make up over 3% of all municipal solid waste, or 6.8 million tons annually. Installing metal roofing over shingles can help solve these issues.

Because metal roofs are so light yet so strong, metal roofing panels can typically be easily installed over your existing asphalt roof shingles without the need to add structural reinforcement. The old asphalt roof shingles under the metal roof simply serve as an extra layer of insulation and water protection and pose no problems to the new metal roof. Of course, each metal roofing over shingles installation is different, so consult your licensed metal roofing contractor to confirm if your roof is suitable for a metal roofing over shingles installation.

metal roof, light yet so strong

· Tricounty Metals

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Metal Roof Vs Asphalt Shingles Repair Costs

Compared to common repairs on an asphalt roof on 100 square feet costing $250$500, because most asphalt shingle roof repairs can only be fixed by replacing the shingle, while common metal roof repairs cost$300$930.

To repair shingles on an asphalt roof, expect to pay $500, vs. $930 for metal roof replacement panel repairs. To seal leaks, tighten or replace fasteners, and caulk a metal roof, expect to spend between $300 and $500.

Install Underlayment Or Framing

Why you may want to consider installing a metal roof

Many people think you can simply slap metal roofing right over asphalt shingles. This would be a mistake. Most old asphalt roofs have shingles that are peeling upward or pooching. Even roofs in good condition will increase about 1/8 of an inch in height with each course, creating a surface that isnt flat.

This uneven surface makes it difficult, if not impossible, to lay the metal panels flat on the shingles. Framing between the two roofs is required to flatten the roof.

Not having a buffer between the two roof materials can also cause damage to your new roof. Without at least an underlayment, the shingles can also damage the metal roofing.

Asphalt shingles are gritty and rough. As metal expands and contracts in the heat, it will rub against that sandpaper-like surface, slowly wearing away the metal roofing over time. Underlayment acts as a buffer to prevent this from happening.

Before beginning installation of the roof itself, decide how youll prep the roof. You have two options: underlayment or framing.

Use Underlayment

Create a buffer between the two roofing surfaces by installing roofing underlayment right on top of the old asphalt shingles. Check building code to see which methods are acceptable in your municipality.

You can use felt or tar paper underlayment or a synthetic material. Roll the tar paper out over the roof and attach with 1-inch roofing cap nails or a staple gun. Make sure to overlap each course of roofing paper by about 2 inches.

Use a 4×4 Frame

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Can You Put A Metal Roof Over Three Layers Of Shingles

If you research how to install a metal roof over shingles, youll find that you cannot put a metal roof over three layers of shingles in most cases. A majority of local building departments will allow one or two layers over of shingles, but not three. Check with yours before you make any decisions or start your project.

Add Underlayer Or Not

Whether to install the underlayer is also an issue. Shingles have a rough texture, which can rub against metal and cause it to lose its protective coating. As the metal wears down, it can be more susceptible to corrosion, thinning, and scratches, reducing the roof’s lifespan.

An underlayment placed between the layer of shingles and metal can prevent these issues. Which type you use will depend on the type of metal you’re installing.

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Installing Edging Panels And Flashing

Youll need to install edging around the roof before you install your panels. Youll need to use corner pieces anywhere the roof bends, and make sure the edging extends about a ½ over any gutters that are installed.

Once its time to install your panels, its crucial that you follow the manufacturers guidelines for roof installation. Metal panels need to be cut and spaced and screwed in a very specific pattern, and that pattern will vary depending on how your home is oriented with prevailing winds and the type of panels youre using. Its also imperative that you use the screws or fastener clips that are recommended, and save your nails for a different project.

If the screws arent properly placed and fastened, they wont be able to withstand the load they are designed for. This placement varies depending on the type of roof. Panels with exposed fasteners and standing seam panels use totally different anchor systems. Aluminum roofing panels will require a much tighter screw spacing than heavier sheet metal.

Experienced roofers will be familiar with your local weather conditions. They also tend to be loyal to roofing materials that they trust and will know exactly how to safely and effectively install it over your old roof.

Labor Cost To Install Metal Roof

How Summer Heat Can Affect Your Roofs

Labor costs to install a metal roof ranges from $3.50 to $12 per square foot, with most homeowners paying about $5 per square foot to install metal roofing. Labor comes out to between $3,000 to install an ordinary roof, and closer to $8,000 for more substantial, thicker, high-end materials. The cost of labor is around 3 to 5 times the rate of the materials alone.

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Installing Metal Roofing Over Shingles

There are two primary methods implemented when installing metal roofing over shingles. The first is running new underlayment over an existing shingle roof, thus covering the old roof. This allows the new underlayment to act as a line of defense in the event that water somehow gets under the metal roof. The second benefit is that it acts as a buffer between the metal roof and the shingle roof. Over time, a metal roof without a buffer can cause the shingle granules to wear away against the back of the metal roofing panels.

The second method involves installing a metal roof over a shingle roof with purlins or battens. In this method, the purlins are screwed down to the roof deck, depending on how the metal roofing manufacturer has designed the panels. The metal is then installed on the purlins. This method gives the installer a nice flat surface to install the metal roofing panels down to without the many grooves and irregularities of the shingles.

Overall, it is up to you the homeowner to decide which installation method is right for you!

Can You Put A Metal Roof Over Shingles

Yes, its possible to put metal roofing over shingles. Before you get started on your project, though, you will need to check with your local building department to see if theyll allow you to. Some areas will only allow re-roofing over one layer of shingles while others will allow over two layers. There are also some disadvantages to installing metal roofing over shingles that youll want to know about before starting. Contact your local roofing company to learn more and see what they can do for you.

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How To Install Corrugated Metal Roof Over Shingles

Ok, so you need a new roof. You may be tired of using shingles and want something else. Something more durable and aesthetically-pleasing than your traditional shingles. Metal roofing materials are always the best option.

But heres the thing, you need a more efficient and effective way to install the new metal roof that will save you time, without incurring extra expenses. You must have asked yourself a dozen times, can I still install my metal roof over this old shingles? The answer to this question and many more hows is what were about to unravel.

Galvanized Steel Shingles Roof Cost

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Galvanized Steel Shingles cost $3 to $3.50 per square foot and start at $7.50 per square foot installed for interlocking steel shingles. The two common types of galvanized steel used in roofing are G-60, which is a low-end product used for roofing on garden sheds or workshops, and G-90, which is used for residential roofing applications. During the manufacturing stage, the metal is treated with a thin coat of zinc oxide and painted with a resin-based architectural coating called Kynar 500 to preserve the finish.

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Cost Of Metal Roofs Vs Shingles

Metal roofing costs between $5.50 to $14 per square foot installed vs. an asphalt shingle roof which costs between $3.50 and $7 per square foot installed. Compared to an asphalt roof on a 1,200 square foot single-story home costing $4,200 to 8,500, metal roofs cost $8,400 to $19,000+.

Many homeowners would instead install metal roofs that look like shingles for a more residential look. Other than metal roof cost lying at 2 to 3 times to cost of asphalt shingles, metal roofs are an infinitely better investment because of their long life and low maintenance. Most metal shingles are made of galvanized steel or aluminum, but some companies offer copper and zinc shingles too.

Contact Legacy Service To Schedule An Appointment

At Legacy Service, we love just about everything about this type of roofing. When they are installed correctly using the right materials, they can withstand just about anything. And since it reflects heat from the sun, it can help you save significantly on energy costs. Its also 100% recyclable, making it eco-friendly. We have decades of experience when it comes to installing this type of roofing, and we can actually custom-make every panel for your project. We also offer a lifetime warranty, which makes for a sound investment. If youd like to learn more about metal roof replacement, contact our Legacy Service team today to schedule an appointment.

Posted on Oct 19, 2019 in Roof

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A lot of elements play a role in maintaining the integrity of the roof, but as a homeowner, the most important components to pay attention to are the underlayment, ventilation, and material.

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Classic Metal Roofing Systems

Classic has very good metal shingles line. The biggest issue is that they work on regional dealership basis. This means there is one contractor per region, no competition, expensive material pricing, and dealers also charge a premium price for installation. In some regions, dealers use pushy sales tactics, talk trash about competitors, but in reality their installation is no better than from small roofing companies.

In my region, the Classic dealer actually hires former Interlock Roofing installers by luring them for a couple more bucks an hour. This means that the quality of installation is on par across big dealerships. The problem with both dealers is that you speak with a pushy salesman and have no idea who your installer will be.

In different areas, these dealers use either subcontractors or directly employ the installers. Bigger dealers have multiple crews, usually subcontractors, who work on volume and want to finish your job as soon as possible, thereby sacrificing quality.

The company has been in business since 1980, and has been installing its US manufactured metal roofs around the globe. Its products are made from 95% recycled materials. They offer a number of beautiful aluminum shingles. They are designed to withstand even the harshest coastal climate conditions.

If you like the look of cedar, there is Rustic Shingle, which boasts a realistic wood texture and is available in 12 beautiful colors.

Will The Warranty On The Metal Roof Be Void If Installed Over Shingles

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The specifications of your metal roof warranty will vary depending on the manufacturer. You, or your installer, must check the metal roof warranty to make sure that you arent breaching the warranty terms by installing it over asphalt shingles. Doing so will leave you without any coverage on your brand new roof.

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Metal Roofing Does Not Attract Lightning

You might think that a metal roof will attract lightning, but this is not borne out by facts or statistics. According to a technical bulletin from the Metal Construction Association, “Metal roofing does not in any way increase the risk of a lightning strike.” Not only that but if metal roofing does happen to get struck by lightning, it is less combustible than conventional roofing materials such as wood shakes or shingles.

As the bulletin asserts, “Because metal roofing is both an electrical conductor and a noncombustible material, the risks associated with its use and behavior during a lightning event make it the most desirable construction available.”

The reason that metal roofs do not attract lighting is simple: lighting seeks a path to ground, which is why trees, telephone poles, and other such structures tend to attract lightning. Metal roofs are isolated structural components, with no direct path to ground inherent in their design. Hence, there is no scientific reason for lighting to strike a metal roof any more often than it strikes an asphalt shingle roof.


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