How to Install Metal Roofing Over Shingles

How to Install Metal Roofing Over Shingles

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James
March 5, 2022
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If you want to refresh your roof’s appearance, you might choose to install new roofing materials over your current ones.

This is an easier way to change how your roof looks, and strengthen it, than removing your existing roof before installing a new one. An example of this is to install metal roofing over your existing roof shingles.

What are the benefits of metal roofs?

Metal is a good choice for a roof because it’s lightweight, resistant to fire and mold, and gives your home a modern makeover. 

But, how should you go about installing metal roofing over shingles? Here’s everything you need to know. 

How To Install Metal Roofing Over Shingles 

How to Install Metal Roofing Over Shingles

One of the reasons why metal roofs are becoming so popular is because they don’t require tricky installation. They can be conveniently installed on your existing roof without a fuss.

Other benefits of metal roofs include lower labor costs because the existing shingles on the roof won’t have to be pulled off. This is also better for the environment because your shingles won’t end up in landfills.

In addition, if your home requires some extra insulation, putting metal roofing over your existing shingles is a good idea as it gives you an extra protective layer that insulates your home to make it more energy-efficient.

What To Know Before Putting Metal Roofing Over Shingles 

There are some important things to bear in mind before you go ahead and install metal roofing over your existing shingles

  • You have to check with local building and zoning departments to check that installing metal over your shingles is approved and allowed. 
  • If your shingle roof is not in the best condition, such as that it has leaks, you first have to inspect it and repair it before going ahead. 
  • If the weight of your roof has serious structural problems, such as sagging, you will need to ensure you repair it first. You can find out  more about sagging roofs by reading, “How To Fix A Sagging Roof.” 
  • You should add an underlayment on top of the existing roof shingles before applying the metal roof. This will prevent the shingles’ granules from making contact with the metal and corroding it over time.

How To Install Metal Roofing Over Shingles 

How to Install Metal Roofing Over Shingles

When installing metal over your existing shingles, you have two options. You can make use of metal panels or metal shingles.

Let’s look at how to install both of these. 

Steps To Follow When Installing Metal Panels Over Shingles 

Start by laying down roofing felt 

This has to be done so that you get a straight and flat foundation. Bear in mind you’ll have to install flashing for chimneys, dormers, or seams where the accumulation of moisture is a concern. 

This layer of underlayment is important because the metal roof will contract and expand according to temperature fluctuations. If there’s no protective layer between the asphalt shingles, which are rough, and the metal roof, this can damage the metal. 

Install the metal roofing 

Keep the edges straight when installing the metal panels. Check that the screws are running in a straight line. It’s a smart move to apply the screws on either the flat surface or the raised roof ridges. The screws need to secure the metal so they will have to be as straight and symmetrical as possible.

Install a 2×4 frame

How to Install Metal Roofing Over Shingles

Underlayment is important but it’s not enough. This is why installing a 2×4 frame of lumber parallel to the roof’s eaves is important. It will support the metal panels on the new roof.

Tip: Measure the length and width of both roof sides and ensure you have enough 2×4 frames that can run parallel to the roof eaves in increments of 24 inches. Start at the eaves and secure the 2x4s to the current roof with the use of screws or nails. 

Install your edging

Edging should be installed around the roof edges, with the use of metal flashing. The corner of the flashing needs to sit flush against the roof edge. You can secure the flashing with 1 ¼-inch nails. Corner pieces should be used to fit around bends on the roof.

If your eaves have gutters, the flashing needs to hang over the gutter lip by approximately ½ an inch.

Other Things To Know About Metal Panels

Metal panel roofing is easy and convenient to install. The panels come in sheets that are around three feet in width and 14 feet in length.

Here are some tips to bear in mind.

  1. You have to place the first sheet so that it hangs over the roof’s edge by about half an inch. The panel has to be square to the roofline, so hold the panel in place while someone else measures both of its ends to the drip edge
  2. Now you can install roofing screws through the metal panels into the existing roof. If you’re making use of a 2×4 frame, you have to check that the roofing is attached to the ribbing at intervals of about 20 inches along the rib. 
  3. Place the next metal panel so that it can overlap the first panel you’ve installed. Attach it in the same way. 
  4. As you make your way to the peak of the roof, ensure that the panels that are higher up overlap with the ones lower down so that the rain will have a proper runoff. 
  5. As you make your way up the roof, you will need to use a saw to cut the metal panels so that they can properly fit around vents and chimneys. 

How To Install Other Types Of Metal Roofs 

How To Install Other Types Of Metal Roofs

How To Install Metal Shingles 

Metal roof shingles come with a strip that gets installed along the eave which can replace edge flashing. Your first course of metal shingles will be secured onto this strip. 

What’s great about metal shingles is that they’re smaller in size as compared to metal panels so you can make adjustments to them to accommodate differences in the roof. 

  1. Lay down a starter row of shingles at the roof’s drip edge. Secure them with roofing nails that will attach the shingles to the sheathing. 
  2. Start installing shingles at the lower corner and make your way up from the roof eave to ridge. 
  3. Metal shingles have a locking system to keep the shingles together, so check the manufacturer’s instructions to be sure you’re using them correctly. 

How To Install Standing Seam Metal Roofing 

This type of roof gets installed from one gable to another. 

  1. Start by installing an eave piece that goes over the eave flashing. 
  2. Then, install the first panel of the metal roof – every panel will run from the eave to the peak of the roof. 
  3. Make sure you plan ahead so that the panels on both roof sides will be the same width, so you can cut them to the correct size. 
  4. You will need a special bending tool for the first piece of metal as it requires a bend-up on its cut side to produce a lip at the gable edge that will direct water to the eave.
  5. Fasten the panel to the roof with the use of metal screws on the tab that is found along the panel’s length. 
  6. The next panel will be secured to the first panel by locking its hem onto the first panel’s tab. Secure it with metal screws. 
  7. After every panel, hand benders need to be used to clamp down the eave cap and the ends of each panel.
  8. When you get to the other gable, measure the width for the last panel piece. It should be the same width as the other gable piece. Cut it to size and use the bending tool so you can bend up the cut edge about one inch and then install the last piece. 
  9. Apply metal flashing. This needs to be installed to direct water away from the seams between the joints where two planes of the roof make contact. 
  10. Install the flashing by covering the roof peak with it. Bend it into a “v” shape. 
  11. Fit it over the top of the roof ridge, and use fasteners to attach it. 
  12. Make sure that the flashing has a one-inch overlap on the roof panels. This ensures that the water will be directed away from the seams. 
  13. Cut your flashing and install it for other joints, wherever two surfaces of the roof connect. 

Note: you will have to install flashing on your metal roof, whether you have shingles, panels, or a standing-seam roof installed. 

Related Questions 

What should you know about installing metal roofing over shingles in wet conditions?

If your region is susceptible to thunderstorms or snow, it’s a good idea to ensure that your roof has underlayment. This is waterproof and prevents the installation of metal roofing material over wet shingles from being problematic in future. 

How much does metal roofing cost?

You can expect to pay between $1.50 and $2 per square foot of metal roofing. As for metal shingles, these cost around $4 to $6.50 per square foot.  

Conclusion 

If you want to save some money and give your roof a makeover, you can simply install metal roofing over your existing shingles.

In this article, we’ve looked at the different types of metal roofing you can use and how to install them.

Sources:

James

James Weldon is a professional roofing contractor with many years of experience on the job. He does not only handle large projects and provide excellent services for his company’s many clients; James Weldon also dedicates his spare time to teaching others useful tricks of the trade. Using BuildCampus as an avenue to reach many roofers and aspiring roofing contractors, James Weldon continues to provide high-quality educational posts and buying recommendations for anyone who visits the website.