How to Install Metal Roofing Over Shingles?

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By George Taylor

Updated: Jan 25, 2024

8 min read

How to Install Metal Roofing Over Shingles

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    If you are thinking of installing a new metal roof over your existing shingle roof, then go all out as it doesn't require pulling apart your existing shingle roof, in turn saving the time and cost. Metal is very lightweight but a sturdy and durable material that weighs only a pound per square foot in contrast to shingles per square foot weight which is approx four pounds. Metal roof installation doesn't increase the load on your pre- existing shingles roof. Cost Saving, perfect insulation and heat reflectors, what you give to your home by putting a metal roof over your existing shingle roof.

    Importance of Metal Roofs Over Shingles

    Choosing a metal roof over shingles has many benefits to homeowners.

    • Durability- One of the most important advantages is the exceptionally long service life of metal roofs. They are extremely durable, withstand extreme weather conditions and can last for decades with little maintenance.
    • Energy Efficient: Metal roofs are energy efficient by reflecting sunlight and reducing heat absorption, which can lead to lower energy costs.
    • Variety: Metal roofing materials are available in a variety of styles and colours, providing homeowners with aesthetic options to enhance their homes curb appeal and potentially increase property
    • Long Lived: Shingles roofing lives 25 years whereas metal roofing has the longevity of 50 years.
    • Recyclable: Metal roofs are recyclable which doesn't happen in the shingles roofing as most of it goes as a waste.
    • Lightweight: Metal roofs are lightweight as compared to shingles, which is 50% heavier than the metal. This makes it a better advantage feature,when you add a metal roof over the shingles roofing than the stress is much lesser on the structure of your home.

    Factors to Consider When Installing a Metal Roof Over Shingles

    Whenever you decide to change your roof please consider below mentioned factors:

    Building Codes and Laws: Some parts in the US such as Florida have some of the strictest building codes in the United States. Fines for violating building regulations can be high. You may not be able to put new roofing materials over the old, no matter what building material you want. Before deciding on a roofing material, check local building codes for more information on roofing requirements.

    Condition of Your Existing Shingles Roof: Problematic older roofs cause problems with new roofing materials. If the roof is not uniformly square, straight and columnar, a metal roof will have waves and wrinkles in the metal materials, or oil prints that can be seen from your yard. This does not affect the structural strength of the roofing material, but can be an aesthetic problem.

    Adding weight to your existing roof can sometimes cause structural damage such as warping or weakening, which will only make your roof problems worse over time.

    Moisture Check: The reason why homeowners choose a metal roof is the durability and longevity of the building material. However, if moisture or condensation remains between the metal roof and the asphalt pavement, it will still cause mould, mildew and rot. An attic is your last defence against moisture. But when the integrity of this attic is compromised, new roofing material is placed on top of the old roofing material, which is likely to cause serious problems over time.

    Warranty: Metal roofing manufacturers may require you to install it directly on your home without old materials. Failure to follow the installation instructions may void the warranty of the roofing material.

    Cost Check: Installing a metal roof over shingles requires costs such as materials, labour and location. The key cost factors to help you take an wise decision:

    • Materials: One of the most important factors affecting cost is the type of metal roofing material chosen. Common materials are steel, aluminium, copper and zinc, each with its own price range. Steel and aluminium are usually more affordable, while copper and zinc are more expensive due to their durability and aesthetic appearance. The thickness and quality of the metal also affect the price.
    • Labour: Labor costs can also vary widely depending on the complexity of the project and the experience of the contractor. It is important to get multiple quotes from reputable installers to ensure you are getting a fair price for this job. Remember that professional installation will likely save you money in the long run by avoiding potential problems with improper installation.
    • Location: The location of your home can have a significant impact on the cost of installing a metal roof over your pre-existing shingles roof. Factors such as local building regulations, climate conditions and accessibility can affect the price. For example, homes located in areas with heavy snowfall may require additional structural reinforcement, increasing overall costs.

    Step by Step Process of Installing Metal Roofing Over Shingles

    Step by step process of installing metal roofing over shingles

    If you want to reduce the cost of pre-installing metal roofing over shingles, you need to take these steps.

    • Remove obstructions such as vents or pipe seals.
    • Repair torn or split tendons Sweep the ceiling and remove any debris that may be a distraction.
    • Be aware of leaks or cracks in the ceiling that could cause further damage if not repaired before installation.

    Now Start the Step by Step Process:

    Clean the Roof: Before installing the attic, make sure the roof surface is clean and free of debris.

    Install the First Layer: Start by rolling the underlayment along the eave so that the bottom edge extends over the drip edge. Secure it with roofing nails or staples, making sure the underlayment is tight.

    Overlap Layers: Add a few inches of overlap between subsequent base layers for weather resistance. Pin each layer tightly, making sure the seams are properly sealed.

    Continue the Roof: Continue the roof and install the loft until you reach the ridge. Make sure each track is properly connected and overlaps the previous one.

    Properly Seal Around Protrusions: Cut holes in the base for pipes, vents and other protrusions. Use appropriate flashing materials to seal these areas and prevent water ingress.

    Attach the Top Layer: When you reach the ridge, cover the top layer of the base coat and pin it. This provides a protective barrier at the top of the roof.

    Check for Gaps or Tears: After installing the underlayment, carefully inspect the entire roof surface for gaps or tears. To troubleshoot, repair or replace the base cover as necessary.

    A metal roof is installed over your shingles roof.

    Disadvantages of Metal Roofs Over Shingles

    Despite the many advantages, metal roofs have some potential disadvantages.

    Affordability: Metal roofs can be up to two or three times more expensive than other roofing materials. Although a metal roof has a much longer lifespan, investing in a metal roof only makes sense if you plan to live in your home long enough to enjoy the cost benefits.

    Noisy: Metal roofs can be noisier than other products during heavy rain or hail, depending on the type of deck, used during installation. Adding attic insulation can sometimes solve this problem, but it can add to the cost.

    Wear and Tear: Expansion, contraction and fasteners. Assemblies of metal roofing materials attached as large panels are designed to expand and contract as they heat and cool. However, both visible and hidden fasteners have different lifespans. Depending on the climate, the neoprene washers and screws used in the installation may wear and loosen over time.

    Inconsistency in Colour Matching: When renovations or additions to the house are needed years later, finding an exact match for the existing metal can be difficult. presentation.

    Accumulation of Moisture: If water accumulates on the roof due to poor installation or repairs, it can eventually cause serious damage. Low-grade metals can also be thinner and less durable. Some metals rust in certain climates or damage more easily than others during a hail storm or during installation.

    Also Read: Shades Of Black Metal Roof


    Installing metal roofing over a roof is one way to maximise the longevity of your new roof while adding a layer of protection. There is also no need to wear out the old roof if the building code does not require it. Metal roofing can be made of steel, tin, copper or aluminium, but steel roofing is popular among people because of its performance. Several roof experts recommend that if your roof leaks, you should consider installing a metal roof because it is resistant to heavy rain, wind and hail, which can last more than 50 years with little maintenance.


    How Long Does a Metal Roof Over Shingles Last?

    Metal roofs last for 50 years in comparison to the shingles roof which only lasts till 25 years. A metal roof over shingles is an excellent option to give longevity to your home roof for fifty years and more.

    Is It Ok to Put a Metal Roof Over Shingles?

    Yes it is good to have a metal roof over shingles as it doesn’t need to dismantle the existing roof and due to its lightweight metal roof doesn’t disturb the overall structure of your home.

    Can You Put a Metal Roof Over 2 Layers of Shingles?

    Most metal roofs are light enough that they can be installed in two layers if the existing roof is in good condition.

    Do You Need Underlayment for Metal Roof Over Shingles?

    Yes, it is good to have a underlayment for metal roof over shingles especially when your area gets occasional thunderstorms or snow, you want to make sure there is a base layer. This underlayment creates a waterproof layer that prevents a metal roof from being installed over a wet tile. It also creates another layer of protection against the moisture.

    Does a Metal Roof Need an Air Gap?

    Creating an air space under the metal roof system increases energy savings in both summer and winter months.

    How Do You Know When It’s Time for a New Roof?

    The only way to be sure of your residential roof’s current condition is to have a licensed professional personally inspect it.

    Should I Install the Metal Directly on the Shingles?

    No,You should never install metal roofing directly on shingles without first installing a synthetic underlayment.

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