Can You Put a Metal Roof Over Shingles?

Do you want to put a metal roof over your existing shingle roof? If the answer is yes, you must be aware of the disadvantages of doing so. This blog answers the question on can you put a metal roof over shingles, or not.

Although metal roofs are durable and long-lasting, installing them over a shingle roof is not always the best choice. Metal roofs, because of their heavy weight, can break the existing asphalt shingles and damage the structure of your home. Similarly, putting a metal roof over a shingle roof has many practical disadvantages. Read on till the end to know more about what happens when you put a metal roof over asphalt shingles, and be able to make better-informed decisions for your roof.

The Reasons Why You Shouldn’t Put A Metal Roof Over Shingles

No doubt, putting metal sheets over shingles provides an additional protective layer to your shingle roof, but is there any benefit of doing so at the cost of potential disadvantages? Putting a metal roof over shingles has many unavoidable drawbacks.

Potential Structural Issues

One of the main reasons to avoid installing a metal roof over shingles is the potential for structural problems. As metal roofing is much heavier than asphalt shingles, adding this extra weight to an existing roof structure can lead to sagging or even collapse of the roof structure itself.

This is particularly true if the structure is not designed to support the additional weight of a metal roof. In fact, many building codes even prohibit the installation of a metal roof over shingles due to the risk of structural damage. Therefore, it is important to carefully consider the potential structural implications of installing a metal roof over shingles before making a decision. Failing to do so can result in costly repairs and even pose a safety risk to you and your family.

It is important to note that reputable roofing contractors will not recommend installing a metal roof over shingles due to these potential structural issues.

Voiding Manufacturer Warranties

Before deciding to install a metal roof over shingles, it is important to check the warranties on both the metal roof and the shingles you currently have in place. Many manufacturers require that their products be installed according to specific guidelines, and installing a metal roof over shingles may not meet these requirements.

As a result, the warranties for both the metal roof and the shingles may be voided. This means that if you experience any issues with your metal roof down the line, your repairs may not be covered by the manufacturer’s warranty.

Therefore, it is crucial to thoroughly review the warranties and ensure that installing a metal roof over shingles will not void them. This can help to protect your investment and ensure that you are not spending money on something that may not work as intended.

Difficulty Of Installation

Installing a metal roof over shingles can be much more challenging and time-consuming than installing a metal roof on a bare roof deck.

This is because a new framing system has to be laid on top of the shingles for the metal roof to be installed, which can be a labor-intensive process. If you decide to simply remove the shingles before installation, this will also require careful attention to detail and a thorough understanding of roofing techniques to ensure that the job is done safely and efficiently.

In addition, the roof deck must be properly prepared for the metal roofing, including checking for any damage or rot. These steps can significantly add to the overall installation time and effort, making it more difficult for roofing contractors to complete their job.

Increased Cost

In addition to the potential structural issues and difficulty of installation, installing a metal roof over shingles can also be more expensive than a complete replacement of a shingle roof, or metal roof installation on a bare roof deck. Therefore, you must take into account the added costs of framing and labor that will go into installing a metal roof over shingles.

These additional steps can add significantly to the overall cost of the project, making it more expensive than installing a metal roof on a bare roof deck. In addition, the added weight of the metal roof may also require additional materials or reinforcement to ensure the roof can support the additional load.

All these factors can contribute to the increased cost of installing a metal roof over shingles. Therefore, it is important to carefully consider the budget for your roofing project and ensure that you have the necessary resources to cover the added expenses of installing a metal roof over shingles.

Trapped Moisture 

One of the key issues with installing a metal roof over shingles is the concern for trapped moisture. Water vapor and moisture can be trapped between the two layers of roofing, leading to the growth of mold and rot if not properly addressed.

Additionally, if the shingles are not removed, you will be dealing with different rates of expansion and contraction between the metal and shingle materials. Fluctuating temperatures cause this to happen, and you want to ensure that both materials have adequate space to expand and contract without breaking down. Therefore, it is essential to carefully consider the potential for trapped moisture, and temperature fluctuations, when deciding whether to install a metal roof over shingles.

Final Thoughts

In conclusion, installing a metal roof over shingles may seem like a convenient and cost-effective solution, but there are several significant drawbacks to consider. The added weight of the metal roof can cause structural issues, void the warranties of both the metal roof and the shingles, and make the installation process more difficult and expensive.

However, deciding whether to install a metal roof over shingles depends on many factors. To truly answer the question on can you put a metal roof over shingles, you must contact a trusted contractor for a roof inspection.

If you are considering a roofing project for your home, we recommend contacting Kickapoo Roofing for expert advice and professional asphalt shingle installation services. Our team of experienced roofing contractors is here to guide you through the decision-making process, and help you find the best choice for your home and budget. So don’t hesitate to contact Kickapoo Roofing today at (608) 247-5261, to find out if you should put a metal roof over your existing shingles.