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Can You Put Metal Roofing Over Old Shingles

How Does Installing Metal Roofing Over Shingles Work

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Before even starting the process of installing metal roofing over shingles, you need to contact local building officials to ensure it can be done. The majority of areas allow for a re-roof over one layer of shingles, while some do allow for a re-roof over two layers of shingles.

Youll want to get this sorted out immediately before you invest in researching a new roofer or worse yet, investing money into a roof you cant have installed on your home.

Why Not Install A Metal Roof Over Shingles

While installing a metal roof on top of shingles seems like it makes the job easier, metal roofs are a challenging project. If you dont have experience in roofing, or skills with metal roof installation specifically, you should always call in a professional roofer with metal roofing experience to ensure the job is well done and damage is avoided.

When bringing in a roofing professional to install a metal roof over shingles, this is the process they typically follow:

First, the roofer creates a slat board base to support the metal roof on top of the shingles. This is created by laying lengthwise furring boards every two feet along the roof, and then attaching them to the roof with 3-inch wood screws from the bottom of your roof up.

Next, they install metal edging around the perimeter of your roof as well as metal sheets to the framing. Metal sheets need to be installed one at a time with screws spaced two feet apart. Each following sheet overlaps the sheet before it.

Once the roof is covered in metals sheets and attached with screws, the roofer will install metal trim along the roofs edge and top ridge. They should then use notching scissors to put a notch in the metal in the middle so it bends over the ridge.

Lastly, the roofer will install closures or a self-adhesive to seal any openings and prevent moisture, debris and pests from getting under your metal roofing.

This may seem like a fool-proof method.

Are There Problems With Your Previous Roof

If there are problems with your old roof, putting a new roof on is not going to fix them. In fact, it will eventually make them worse.

If your previous roof weighs more than the structure of your home can adequately handle, adding the additional weight of the metal roof will cause a bigger problem. Some warning signs of problems from the weight of your roof may include buckling trusses or sagging roof decking. Prior to installing a metal roof over an existing shingle roof fix any rotten wood sheeting or rafters.

If your asphalt shingle roof has leaks, those problems need to be addressed. Parts of the roofing system may have water damage, and these issues would have to be repaired or replaced. You may have already noticed water damage issues that led you to determine you need a new roof in the first place. Ignoring these issues will lead to a shorter lifespan for your new roof and more expenses in the future.

Read Also: Do I Need Permit For Roof Replacement

Can Metal Roofing Be Installed Over Shingles

Metal roofs offer the type of longevity and durability not often found in home building materials. In the humid and moist climate of Northern Florida, they can prove a far better option than traditional shingle roofs. Unfortunately, many people shy away from investing in a metal roof due to higher costs. Part of the high cost of metal roofs stems from installation best practices. After all, tearing off a shingle roof to install a metal roof can incur double the costs. This leads many to ask whether or not a metal roof can simply be installed over top of a shingle roof. Were here with your answer!

Metal Roofing Over Existing Shingles Applications

Classic Ribbed Metal Roofing

While recover options arent always the best solution for every roof, a roof recover system can be an ideal solution for many, and weve completed a lot of recover projects over the years. From schools to airplane hangers, you can check out some of our recover projects in our .

If youd like to learn more about the details of some of our roof recover applications, check out these resources:

Read Also: A Plus Roofing And Remodeling

Laying Metal Roofing Over Shingles Step

By laying metal roofing over the shingles of an existing roof you are protecting it from the weather and also from the effects of time.

A Serious Project

Overlaying a shingle roof with metal is a difficult project, one that really falls into the semi-professional category. If not done well, not only do you risk damaging the existing roofing materials, you may damage the entire roof. Care should be taken when attempting this sort of large-scale project to get the best materials and if possible enlist some help from others who have done this type of job before successfully.

Step 1:

Find the best way possible to get to the roof with the tar paper.

Step 2:

Starting at the bottom or at one end of the roof lay the felt across the entire length, and then work your way to the top or center with over laying sheets and as you overlay use the nails to pin this down. If you are working on a windy day, you will definitely need two people for this job.

Step 3:

When the felt is secured you can start laying the metal shingles. Again start at the bottom and nail the shingles into place. Then work your way up to the top or center of the roof. The shingles need to be offset in every space, so there are no valleys or blank spaces where a leak will start.

Step 4:

Make a chalk outline of the horizontal and vertical measurements so that you can lay the next set of shingles into place quickly.

Step 5:

If the roof is peaked, there will be a ridge. You will need to nail the ridge roll into place.

Is Roof Underlayment The Same As Vapor Barrier

This question isnt as simple to answer, because it depends on the type of material. There are a variety of products used as underlayment when a new roof is being installed. Some are waterproof, some are water resistant. And for areas that get extreme cold and dam formation is common, waterproof underlayment rather than simply water resistant products are highly recommended. There are also parts of a roof like eaves and valleys where waterproof underlayment should be used, even if the rest of the roof has a water-resistant product on it.

There are no hard and fast rules for metal roofing installation, because each home is different. We will work with you to come up with the absolute best solution for your new roof, whether that includes tearing off the old roof or leaving it on. And well suggest what we believe is the right underlayment and/or vapor barrier. We want you to be absolutely satisfied with your new metal roof, and its our goal that it will provide exceptional performance for decades. For a free quote, please call or text us at 763-785-1472.

Read Also: How Can You Tell If Your Roof Is Leaking

Cost To Install A Metal Roof

Metal roof installation is a labor intensive task, requiring a competent, skilled roofer with a great deal of experience to manage this type of installation project. When youre using a more expensive material, the cost to install a metal roof can be on the higher end of the scale. However, the benefits that come with a metal roof are worth the investment.

Putting A Metal Roof On Top Of Shingles

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Installing metal roof over shingles can be done in two ways. The first phase entails applying new underlayment to the shingles. In the event that water migrates underneath the metal roof, the underlayment will provide an efficient line of protection. The underlayment can also serve as a barrier between the shingle and metal roofs, preventing granules from corroding the metal over time.

The second approach involves installing the new metal roof with battens or purlins. Depending on the configuration of the roofing panels, the contractor screws purlins into the roof deck with this process. The purlin framing is then covered with the metal roof. This approach allows the contractor to create a smooth surface for roofing panels without dealing with the numerous grooves and other irregularities that come with shingles.

A reliable roofing contractor at ReRoof America will assist you in determining which installation method is best for your home. We as a commercial roofing company will also advise you about whether or not a metal roof is a good fit for your home.

Recommended Reading: How To Fix A Leaking Roof

You Wont Get To Replace Crucial Roofing Materials

When you get a metal roof-over, you bypass the tear-off process of getting a new roof. This will save you money, but you miss out on replacing crucial materials that are included in a full roof replacement.

For example, one of these crucial materials is the underlayment. Its your roof systems last line of defense for keeping your decking dry. When you roof over your asphalt roof with a metal roof, you have to rely on the underlayment from your old roof. You also wont get the proper kind of underlayment specifically designed for a metal roof.

Roofing materials arent meant to last forever. Thats why if youre already going to invest in a metal roof, I recommend starting from scratch with clean decking.

To learn more about the crucial materials that are replaced when you get a new roof, read this article on the 9 materials included in your roof replacement.

The Cons Of Installing A Metal Roof Over Shingles

Some significant problems may appear after installing a metal roof over shingles. Next, we will show you in detail the reasons why you should remove your old shingles before installing a metal roof.

  • It is difficult to inspect Your new metal roof will need a solid foundation. This base will be the wooden deck under your old roof. So, if you install a new metal roof over the shingles, your roofer will not be able to check your roofing deck condition.
  • Only by completely removing the old shingles you will know if there are issues like rotten wood. If problems like those exist in the deck, you will have to rebuild the entire roofing system.

  • It can generate an uneven surface: The furring boards the roofer place over the old shingles may create an uneven surface. These boards can absorb humidity from the environment and get bend over time. So, it may deform your metal roof with the pass of time.
  • It can reduce your metal roofs useful life: Installing a metal roof over shingles may not be the best decision. But, to do that without laying a wooden base where to build on is even worse! And some non-professional roofers do that.
  • When affixing metal roofing panels directly to shingles, the asphalt granules will wear the metal roofing coating reducing its lifespan.

    In conclusion, the best you can do is to remove the existing shingle roofing system. Later, you can install your new metal roof correctly.

    Read Also: How To Keep Squirrels Off Your Roof

    Laying Steel Roofing Over Shingles The Right Way

    • Written by Robert Miller on Apr 20, 2010To ensure our content is always up-to-date with current information, best practices, and professional advice, articles are routinely reviewed by industry experts with years of hands-on experience.Reviewed by

    Steel roofing offers many benefits over slate tiles or asphalt shingles. Metal roofing is resistant to fire, rot, and termites. Manufacturers provide 30-year warranties on metal roofing products. Installing steel roofing over existing roofing materials is fairly simple. Use furring strips to build a slat board on the roof, then mount the steel sheets to the slat board. Some consideration for vent stacks and chimneys is required during the design process. Installing a steel roof will cost approximately $60 per square foot.

    Step 1 Work Safely

    Choose a day with calm weather to work on the roof. Metal roofing is very slippery when wet. Brace your extension ladder correctly when climbing onto the roof. In some cases, you can lean the metal sheets against the roof surface on the ground and lift them up from the roof while working. This is preferable to carrying large stacks of sheets up a ladder.

    Step 2 Measure Roof

    Step 3 Install Slat Board

    The furring strips are 1×4 pine boards. Secure them to the roof with wood screws at every 4 to 6 inches. Install the slat board as described above.

    Step 4 Install Edging

    Bend the metal edging to your needs if necessary and fasten it to the roof with nails at every 4 to 6 inches.

    Does The Building Code Allow For A Metal Roof To Be Placed Over Shingles

    Metal roof installed over 2 shingle layers last October ...

    The choice is easy when there isnt a decision to be made. Local building code can make your decision simple if it specifies that the existing shingles have to be removed first.

    Its common to find building codes that will allow for two layers of roofing on a structure, but that is not always the case. Check your local building codes to see what is allowed in your area. Not complying with building codes can result in expensive fines.

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    Can Architectural Shingles Be Installed Over Architectural Shingles

    Several readers have recently asked me if they can have architectural shingles installed over existing architectural shingles during a re-roofing project. With the growing number of architectural shingles being used today its no wonder the question keeps coming up. So in this article Ill go over this issue and some of my thoughts on the subject.

    Roof Plan Or Roof Scam

    Q: My friend has a new 9,000-square-foot home and has had problems with the roof leaking. The roofing man and two painting guys have told her that the caulk on her roof was the source of the problem. They told her that she should have it checked every six months for cracking and possible replacement because the caulk doesn’t last long. I have never heard of this before and was wondering if they are pulling her leg or if this is a real problem?

    Shari, Park Hills, Mo.

    A:Tom Silva replies: I’ve got to tell you, it sounds like they’re pulling your leg. You shouldn’t need any caulking on a roof with proper flashing. You need a second opinion.

    Also Check: How Much Does A Roof Cost On A House

    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

    The Importance Of Roof Pitch

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    Q: Everything being equal , which roof will last longer: one with a steep pitch or one with a shallow pitch? Seems to me a steep hillside erodes more quickly than a low slope, so I’d think that roof shingles would wear out more quickly on a steeply sloped roof.

    George, Oglesby, Ill.

    A:Tom Silva replies: It’s difficult to say. On one hand, a steep roof is less likely to collect leaves and other debris that hold moisture against the shingles and invite the growth of moss and algae. On the other hand, that same roof in an unshaded area facing due south will take the full brunt of the sun, which is hard on any roof.

    Actually, factors other than pitch have a greater effect on shingle durability. The side facing your worst weather typically fares worse than the leeward side. Likewise, a roof system that isn’t vented properly and allows heat to build up beneath the roofing has a shorter life than one that is vented.

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    Installation And Repair Usually Requires A Professional

    DIYers have been known to install and repair metal roofing, but it is generally not advised. Metal roofing is generally available only through select retailers, and the techniques for installation and repair are specialized skills. If you opt for metal roofing, you will likely be calling a specialist should problems occur. Fortunately, such problems are rare with metal roofs.

    Three Ways To Install A Metal Roof Over Shingles

    Metal Roofing Info, New / Media

    There are three ways to install a metal roof over shingles. In this article, I will go over the three different ways and what their pros and cons are. The local building department should always be consulted with because each department might have their set of requirements for doing a replacement roof in their county or city.

    1) Remove the Shingles before Installing the Metal Roof The first way to install a metal roof over shingles is by completely removing the old shingles before installing the new metal roof. A benefit to doing it this way is that you can see if there is any rotten plywood that needs to be replaced before installing the new roof. Most roofers can walk around the roof and feel for soft spots, which indicates rotten or deteriorating plywood. However, this technique is always fool proof either. If you have a bad leak in your roof for a long time, it might be best to get into the attic and look up at the roof to see if you notice any plywood that needs to be replaced. You will have a much stronger metal roof if it is being installed into good wood as opposed to rotten wood.

    Here are the Pros and Cons to Removing the Shingles


    • Get a good look at the overall condition of the roof before installing a new metal roof
    • Have the opportunity to nail off the plywood to new and more stringent Florida building codes


    Here are the Pros and Cons to Installing the Metal Roofing Right over the Shingles


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