How to install metal roofs over shingles (yes you can)

It is inevitable that your roof will fail at some point. This part of your home is constantly exposed to natural elements, damaging even the most resistant material. Although asphalt shingles have proven to be perfect for this job, they even need to be replaced. Maybe it’s time to replace it with a metal roof, and contrary to your opinion, you don’t have to remove your current roof for it to work. If you want to know how to install metal roofs over shingles, you’ve come to the right place.

When it comes to metals, many alternatives are perfect for waterproofing the roof, such as copper, aluminum or even zinc. Steel is the most popular, which is why manufacturers have decided to give it different shapes to make it more attractive. Once you’ve found the perfect metal roof, it’s time to learn how to install it.

No additional costs required

Metal is a material that has the advantage of being light so that it can rest on the existing structure of asphalt and tiled roofs. Installing a metal roof over shingles is more common than you think. Many homeowners choose this alternative to reduce installation costs.

Although it sounds obvious, you can get extra insulation if you put a layer of metal over your tiled roof. Another positive aspect of installing metal over the existing roof is that you don’t have to remove the old tiles, which in turn leads to lower costs.

One problem with metal ceilings is that they are very loud. That is why it is used in factories where they do not interfere, but in homes it is not acceptable. However, since there is brick and asphalt under the metal roof, these will dampen the sound and drastically reduce the noise generated.

Just because this is possible does not mean that you can start the project immediately. There are some things you need to check before starting it. The first is that your city’s building codes allow it. In most states, you can’t have more than two roof layers. As soon as this limit is reached, you can only remove the existing ones.

Another important aspect is that it is not recommended to install a metal plate on a roof in poor condition. Rotten or broken ceilings do not support the replacement of a shingle roof with a metal roof. Since the sheets are screwed together, any excessive force can put them in place.

If you’ve already checked these points, you can learn how to install metal roofs over shingles. First, however, you should know the benefits.

Advantages of installing a metal roof over shingles

Image source: Whitten Architects

Even though people hated once Installation of metal roofsit has now become a common choice among people. Thanks to new technologies, some of the negative points that the metal had compared to asphalt and tiled roofs, such as. B. the appearance, are eliminated. The manufacturers have managed to hide the material perfectly.

Some of the advantages of metal ceilings are:

• Metal is the lightest roofing material on the market, so the integrity of the structure of your home is not compromised.
• Thanks to their weight, they can be installed over other ceilings.

Image source: Smith & Vansant Architects PC

• Those who already have a previous roof enjoy additional protection from the weather and noise. This is particularly useful to avoid leaks.
• The metal roof has a noise level similar to that of brick when installed together.
• The materials used for metal roofs do not attract lightning and are therefore safe. They are also fireproof and cannot be pierced by insects.
• The metal price is lower than for other materials.
• Unlike a tiled roof, metal can last up to 50 years before it needs to be replaced.
• The metal roof can be recycled at the end of its useful life.

How to install metal roofs over shingles: different methods

Image source: Dan Nelson, designs northwest architects

Although there are several methods, the basic idea of ​​installing a metal roof over shingles is the same in all cases. You need solid support over your current shingles to screw the metal plates on.

For this reason, there can be no loose, rotten or perforated leaves. If your current roof has any of these properties, you must first replace the damaged areas.

Also note that your roof may not be prepared for additional weight. If you notice signs of kinking or other deformation of the ceiling in your home, it is best to contact an expert for advice on the feasibility of the project.

Now you can learn the two methods of installing a metal roof over shingles.

Use a synthetic base

The first method requires the installation of an insulating layer between the tile roof and the sheets. This layer generally consists of plastic derivatives and papers such as tar paper (although their use has been replaced by other options).

This layer is required to protect the metal from the shingles, otherwise it can corrode and rust. Since the metal constantly contracts and expands due to heat, the friction generated can quickly damage both roofs.

The process is simple. The paper sticks to the bricks like a new asphalt coat, and later the metal roof is placed over it.

This method has several advantages that need to be highlighted. This base between the bricks and the metal not only allows the metal to slide without damage, but also acts as an additional layer of insulation against possible leaks in the roof. It will also act as an additional insulator for weather and noise.

With purlins and slats

There is an alternative in which it is decided not to use the additional insulating layer for the installation of the metal roof. Straps or purlins are used, which are screwed along the ceiling and serve as support for the metal plates.

The use of purlins as the base for the metal enables a more practical installation because it offers a stable floor to lean on.

The straps also keep the metal roof away from the old tiles and asphalt, so that corrosion is completely avoided.

The purlins offer much more resistance than the first method, since a band and a plywood board carry the metal. However, the process can be a little more complicated than installing a synthetic layer. It is therefore recommended that a professional do this.

Final thoughts on how to install metal roofs over shingles

Knowing how to install metal roofs over shingles is only part of the process. After you have the knowledge, you should anticipate some aspects. The most important thing is your safety. The roof is one of the most complex work areas due to its height and the lack of lateral protection. Therefore extreme caution is required.

In addition, the installation of metal roofs over shingles poses material risks. You need suitable protective equipment to avoid accidents during work.

If you want to install a new roof over an existing one at the construction level, there must be openings through which hot air can escape and cannot accumulate. If your ceiling is a flat sheet, the purlins or synthetic sheath must be placed at an intermittent speed to create these vents.

Certain rooms, such as B. drip edges must be insulated with foam so that no water penetrates into the ceiling. The same applies to other construction elements that come out of the ceiling, such as. B. fireplaces. Instead of foam, you should use flashes.

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