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Can You Put Metal Roof Over Two Layers Of Shingles

Your Roofing Contractor Cant Inspect Your Roof Decking

Can You Put a Metal Roof Over a Shingle Roof?

Roof decking is the foundation of your entire roof system. When nailing over your old shingles, theres no opportunity to inspect the decking before installing your new roof.

If there is a problem with the decking and one of the boards breaks during installation, the contractor will take off the old shingles, replace the decking, put the old shingles back on, and start installing again. This adds to the time it takes to replace your roof and can even add to the final cost of the job.

On the other hand, your roof is taken down to its decking when getting a full roof replacement. This gives your contractor a chance to inspect the deckings integrity to see if it can handle your new roof.

If they find any problems with your decking, theyll replace it before installing your new roofing components.

How To Install Metal Roofing Over Shingles

Reviewed by Tomas Kalkys. President.Qualifications: More than 20 years of experience in residential and commercial exterior remodeling.Founding farther of Legacy Service.Written by LegacyUSA Team

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So, you need a new roof. You may have shingles now, but are shingles your best choice for the years to come?

Maybe, but have you considered your other options? Metal roofing is one of the best types out there for any building, including all kinds of homes. Not only are they visually appealing, but theyre also much more durable than shingles. If youre considering getting a metal roof, you may be wondering if you can install it over shingles. Were going to answer that question in this blog, so keep reading or give our Legacy Service team a call at 215-798-9790 if youre considering a metal roof replacement.

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.

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Install Underlayment Or Framing

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

How To Install A Metal Roof Over Existing Shingles

Install Metal Over Shingles?
  • Start with an underlayment over the existing shingles:You must put in a completely new underlayment over the existing shingles before you carry out any installation. This will help prevent water leakage and provide a buffer between the metal roof and the existing shingles. Shingle roofs are granulated, metals on the other hand contract and expand, with time, without an underlayment, the shingle granules would wear out.
  • Using purlins or battens:The purlins have to be screwed to the roof deck, the metal is then installed onto the purlins. The advantage of using purlins is that they provide the installer with a flat surface to install the metal roof panels without the issues that come with shingles. The metal has to be attached to three-quarters of the purlins and at least half of the plywood which helps in making the roof stronger. Purlins also create an air gap between the metal roof and the shingles. This gap acts as a buffer for these shingles below when the metal roof heats up during summer.
  • Also Check: Where To Buy Metal Roof Shingles

    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.

    Can You Put A Metal Roof Over 3 Layers Of Shingles

    An experienced roofing contractor will answer yes to the question: Can you install metal roofing over shingles?. The work may require additional steps, but you can build one layer of roofing on top of another and have a roof composed of various materials. One of our roofing providers will help you complete this installation from start to finish.

    Do the Shingles Need to be Removed?

    Its not necessary to remove a shingle roof first to install a metal roof. Any good roofer is willing to install a metal roof over an existing one. One reason why the metal roof is so popular is because the installation is fast, easy and affordable.

    How Many Layers Can Sit Under the Roof?

    One to two shingle layers can rest safely and securely under a metal roof. Any more than two layers could reduce the stability of your roof. Many building safety codes will not allow more than two layers, so check your local areas before making an installation.

    Another tip is to evaluate the current condition of your shingle roof. Poorly designed shingles make it more difficult to install a new roof. Removing or repairing the shingles may be the safer option than covering it with new materials.

    Our professional roofers will answer all of your questions and concerns about this unique installation. You dont want to install a new metal roof and still have to deal with leaks in the ceiling. Have us carry out a thorough inspection first.

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    How Long Does A Metal Roof Last

    metal roofroofMetalmetal roofsroofroofDIY metal roofing installations will require the following materials:

  • Ladder or scaffolding
  • Jigsaw or power metal shears.
  • Steel panels
  • Staple gun.
  • Drill and full assortment of drill bits.
  • 1 ¼ inch roofing nails.
  • Metal roofing screws.
  • Does Material Affect Metal Roofing Prices?

    • Aluminum – The material price range is $3.75 to $5.50 per square foot.
    • Steel – Galvanized steel is the most affordable.
    • Standing Metal Seam – The standing seam metal roof is more expensive at $4 to $6 per sq.
    • Copper and Zinc – The cost is $9 to $14 per sq.

    Can You Install A Metal Roof Over Asphalt Shingles

    Metal Roof Install Over Shingles

    People have been installing metal roofs over layers of asphalt shingles for decades in fact, it used to be common practice and likely would have been considered wasteful in terms of time and energy not to do it. This practice is done less and less with asphalt on asphalt shingles, yet many people still find it acceptable to bury a shingle roof under a metal roof.

    There are pros and cons to most methods for home improvements, and roof-overlays are no exception. On the positive side, not tearing off the old asphalt shingle roof when installing metal roofing can save time and money. It can also arguably increase the R-value of the roof and act as an increased sound barrier. On the flip side, not tearing off the additional layers of the current roof increases the load of the roof, void or reduce manufacturer warranties, may impact the aesthetics of the new metal roof, and keep serious construction issues hidden.

    Here are the benefits and disadvantages of installing a metal roof over an asphalt shingles roof, along with things you might not have considered and, ultimately, whether you should do it or not.

    Also Check: What To Know About Getting A New Roof

    Does A Metal Roof Lower Your Insurance

    Thats why having a newly installed roof can save you on insurance premiums. Insurance companies also look favorably on metal roofing because research has shown that homes with metal roofs receive less damage from storms and house fires, which means the company is much less likely to have to pay an insurance claim.

    Can You Install A Metal Roof On Top Of A Traditional Shingle Roof

    The answer to this question isnt as cut and dry as some people assume. Lets say that your home has a traditional shingle roof, and now you want a metal roof because its more durable. So, the question is, do you need to tear off all the shingles first? The answer is no, you dont need to tear all the shingles off the roof because metal roofing can be installed on top of them.

    The biggest advantage of metal roofing is that even though metal is generally seen as being heavy, metal roofing is light. Thats why metal is the perfect material, especially for roofing on top of shingles. That said there are a few considerations worth making.

    The most important being local building codes. Now before you have a roofing company pave over the Shingles with a Metal Roof, you will want to check with the local building department to see if they approve of it. However, you shouldnt have a problem with 60% of American municipalities.

    Also Check: How To Calculate Amount Of Shingles For Roof

    Ensure All Your Roof Flashing Is In Place

    Install flashing on every section of the roof where two parts of the roof meet at different angles or where the roof meets a wall or chimneys.

    Use roofing nails to lock the flashing down, Nail the edges and ensure that you leave the center free of nails, pins at the center or too close to the center of the flashing could lead to leaking of your roof.

    The Weight Of The Roofing System

    How to Install Metal Roofing Over Shingles

    Most buildings are designed to support the heaviest roofing systems. However, the combined weight of asphalt shingles and metal roofing may require additional support in the roofing structure. This is especially true if the structure is older and not designed for modern roofing materials. Before undertaking a residential or commercial metal roof installation, make sure the building can support both roofs long-term.

    Recommended Reading: Can You Claim A New Roof On Home Insurance

    Can I Diy A Metal Roof

    While most metal roofing styles can be installed as an advanced DIY project, metal roofing installation is complicated and can vary slightly based on the brand of panels or shingles that you select. We recommend that you install a metal roof with one or two helpers and fall protection equipment designed for roof work.

    Do I Need Underlayment When Installing Over Shingles

    All roofs need an underlayment. However, when installing a metal roof over shingles, the shingles may be able to act as an underlayment. Over time as the shingles deteriorate, you may need to replace them with a proper underlayment. That said, if you do not wish to remove the shingles initially, it is best to ensure an underlayment is installed over the old shingles.

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    Metal Panel Attachment Into Furring Or Lathing Strips

    In this scenario, wood purlins or sub-girts are used as furring strips on the old roof and attached to the structure below. This framing system can be installed directly over existing shingles or applied over existing decking or underlayment. The new metal roof panels are then attached to the framing system.

    The image above illustrates a general furring strip approach, although, as you might guess, there are numerous variations to this method. This method typically involves less mess than a complete tear-off.

    However, with the added cost of the furring material and installation, the final price can be similar to tear-off. Although, it is undoubtedly more environmentally friendly since the shingles remain in place. This approach does add some weight to the roofing system, so its essential to determine if the structure can support the additional weight.

    For more on this technique, check out this white paper by the Metal Construction Association.

    When using this approach, its important to remember that the copper elements in pressure-treated wood may aggressively attack metal panels. Consequently, if using pressure-treated lumber for furring applications, a barrier of #30 felt or synthetic underlayment should be used between the wood framing and metal panels.

    Do I Need Underlayment For A Metal Roof Over Shingles

    Considerations When Installing Standing Seam Metal Over Shingles

    All roofs need an underlayment. If youre installing a metal roof over asphalt shingles, the shingles may be able to act as an underlayment for the roof. However, the shingles expanding and contracting can cause damage underneath the metal roof over time. For this reason, its usually recommended that you remove the shingles on your home before installing a metal roof.

    Read Also: Can I Pressure Wash My Roof

    Can I Have Metal Roofing Installed Over Shingles

    In short, it depends.

    You’ll need to know a bit about your roof’s history to determine if you can have metal roofing installed over your existing shingles. How many layers of old roofs lay beneath the surface?

    If you have two roof layers, most building codes will require you to remove and replace them with an entirely new one. However, if you have one layer of roofing only, then you could add another on top.

    You should check with Calgary roofing experts to see if your roof is a candidate for metal roofing, especially if you want it installed over the shingles you already have.

    Benefits Of Metal Roofs:

    Metal roofing has proven over the years to be a great selection for you as a homeowner. They are durable in comparison to shingles which means they can even last a lifetime.

    Due to their durability in nature, they tend to save you on money unlike with shingles as you have to keep replacing them. Metal roofs, on the other hand, need minimal to no repair.Metal roofs have over the years have become a household must-have. They have helped homeowners upgrade the look of their homes while giving their homes a lasting value. Some of the benefits of metal roofs include: They are extremely versatile and can match different styles. Metal roofs are fire-resistant. This means that you do not have to worry in case of any fire accidents. They are energy efficient and are great at keeping homes cooler. Metal roofs are lightweight in comparison to other types of roofing such as shingles. Metal roofs are durable. They can last a lifetime without the need for replacement. Their ability to withstand adverse conditions acts as an added advantage. They allow for maximum shedding of rain and snow as metal panels interlock with each other and their surface is slippery. They are wind resistant due to the nature of the panels interlocking with each other. They are made of recycled material and can also be recycled at the end of their lifespan which is technically a lifetime. This makes them very environmentally friendly. They are very adaptable and can fit into various designs.

    Recommended Reading: How To Stop A Roof Leak Temporarily

    Covers Up Unknown Problems

    The biggest reason not to do a roof overlay is that you never know exactly what you are covering up. Leaks in roofs can go undetected for years, resulting in rotten sheathing and even rotted rafters and trusses, not to mention mold. As a roofing contractor, due to these liability and warranty reasons, I will not ever do a roof overlay for a customer the risk is just too significant.

    If there is a leak issue present that is not resolved and continues to occur, to fix it, you will have to remove the metal and shingle layers to find the base layer that is the issue. This process can be costly especially if the metal layer is a standing seam. With standing seam metal, you cannot simply remove one or two panels because of how they are interlocked thus, the roof often must be torn off back to the edge of that plane of the roof.

    If you decide to do an overlay, be cautious about trapping condensation under the new metal roof. You might consider laying down furring strips to provide a gap between the two roofs for better airflow and ventilation.

    Can I Install A Metal Roof Over Shingles

    Can I Install a Metal Roof Over Shingles? ⢠Rare Manufacturing

    When it comes to replacing your roof, you may be considering a transition to metal instead of wood or asphalt shingles. After all, there are many benefits to metal roofs.

    The biggest question people have about metal roofs is if you can install this roofing over the top of asphalt shingles. The short answer is yes. In most cases, it is possible to place metal roofs directly over shingles without removing the existing roof. However, there are some situations where it wouldn’t be possible.

    Keep reading to learn all about installing a metal roof over shingles and the dos and don’ts of this roofing method, including metal roof over shingles problems you may experience during or after installation.

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