How to Install a Metal Roof Over Shingles

Last updated on January 4, 2024

Discover the step-by-step process of installing a metal roof over shingles, ensuring you achieve a durable and efficient roofing solution for your home.

Are you tired of constantly repairing or replacing your old shingle roof? Upgrading to a metal roof can save you time and money in the long run. But what if you don’t want to go through the hassle of tearing off your existing shingles before installing a new metal roof? The good news is, it’s possible to install a metal roof over shingles! In this article, we’ll guide you through the process of installing a metal roof over shingles and provide tips on how to ensure that your new roofing system lasts for years to come.

So, grab a cup of coffee and let’s get started!

Benefits of Installing a Metal Roof Over Shingles

how to install a metal roof over shingles

First and foremost, it saves you the time and cost of tearing off your old shingle roof. This means less labor, disposal fees, and potential damage to your home’s structure during the removal process.

Metal roofing is more durable than traditional asphalt shingles. Metal roofs can withstand extreme weather conditions such as heavy rainstorms or hailstorms without sustaining significant damage.

They are also resistant to fire and pests like termites that can cause extensive damage to other types of roofing materials.

Metal roofs are energy-efficient too! They reflect sunlight instead of absorbing heat like asphalt shingles do which helps keep your home cooler in hot climates reducing cooling costs by up to 25%. Installing a new metal roof over existing ones increases insulation value which translates into lower heating bills in colder months.

Evaluating Old Shingles

If they are severely damaged or deteriorated, it may not be wise to install a new roofing system on top of them. Doing so could result in an uneven surface that can compromise the integrity and longevity of your new metal roof.

To assess whether your old shingles are suitable for installation under a metal roof, start by inspecting their overall condition. Look for signs of wear and tear such as cracks, curling edges or missing pieces.

Check if there is any moisture damage or mold growth underneath the existing shingle layer.

If you notice significant damage or deterioration in more than one area on your old roofing system, consider removing them before installing a new metal roof overtop. This will ensure that you have an even surface to work with and prevent future problems from arising down the line.

Choosing the Right Metal Roofing Material

One of the most important is durability. You want a roof that can withstand harsh weather conditions and last for many years without needing repairs or replacement.

Another factor is cost. Metal roofs can be more expensive than traditional shingle roofs, but they also offer long-term savings in energy costs and maintenance expenses.

The type of metal you choose will also affect its performance and appearance. Steel is a popular choice due to its strength and affordability, while aluminum offers superior resistance to corrosion in coastal areas.

Copper provides an elegant look with natural patina over time but comes at a higher price point compared to other metals like zinc or galvanized steel.

Ultimately, selecting the right metal roofing material depends on your budget, climate zone where you live as well as personal preferences regarding aesthetics.

Stone-Coated Steel Shingles Vs. Painted Steel Shingles

Two popular choices are stone-coated steel shingles and painted steel shingles. Stone-coated steel shingles offer the look of traditional asphalt or slate roofing but with added durability and longevity due to their metal construction.

They also come in a variety of colors and styles, making them an attractive option for homeowners who want both style and function.

On the other hand, painted steel shingles offer a sleeker appearance with solid color options that can complement modern architectural designs. While they may not mimic traditional roofing materials like stone-coated steel does, they still provide excellent protection against harsh weather conditions.

Ultimately, which type of metal roof you choose will depend on your personal preferences as well as factors such as climate considerations and budget constraints.

Differences Between Standing Seam and Exposed Fastener Systems

Both options have their pros and cons, so it’s important to understand the differences before making a decision.

Standing seam roofs feature interlocking panels that run vertically up the roof surface. The seams between each panel are raised above the level of the roofing material itself, creating a distinctive look that is popular in modern architecture.

This type of system is known for its durability and resistance to leaks since there are no exposed screws or nails.

On the other hand, an exposed fastener system uses screws or nails with rubber washers directly through each panel into your roof deck. While this method can be more cost-effective than standing seam systems due to less labor involved in installation; however they tend not last as long because over time these washers will dry out causing water penetration which leads rusting on your metal panels.

Necessary Tools and Materials

Here are some of the necessary items you’ll need:.

Tools:

  • Power drill
  • Circular saw with a metal-cutting blade
  • Tin snips or aviation shears
  • Chalk line
  • Tape measure
  • Hammer
  • Screw gun or impact driver

Materials: – Metal roofing panels (measured and cut to size) – Roofing underlayment (synthetic felt or self-adhering membrane) – Furring strips or lathing strips (if needed for ventilation purposes) – Screws, nails, and other fasteners specific to your chosen system.

Make sure that all of your tools are in good working condition before starting the installation process. It’s also important to wear appropriate safety gear such as gloves, eye protection, and sturdy shoes with good traction.

Having all these necessary tools at hand will make your work easier while ensuring that everything is done correctly from start to finish.

Preparing the Roof Surface

This step is essential to ensure that your new roofing system adheres correctly and lasts for years without any issues. The first thing you need to do is inspect your old shingles thoroughly.

Look for any signs of damage or wear and tear, such as cracks, holes, or missing pieces.

If you notice significant damage on the existing shingle layer, it’s best to remove them entirely before proceeding with the installation process. However, if they are in good condition overall and only have minor issues like curling edges or small cracks here and there – then you can proceed with installing a metal roof over them.

Once you’ve assessed the state of your old shingles layer(s), clean off any debris from their surface using a broom or blower machine so that nothing interferes with adhesion between layers during installation.

Installing Furring Strips or Lathing Strips

This is where furring strips or lathing strips come in. These are thin pieces of wood that are attached perpendicular to the roof rafters and provide a level surface for the metal panels.

To install furring or lathing strips, start by measuring and marking out where they will be placed on the roof. The spacing between each strip will depend on the type of metal roofing you’re using, so consult with your manufacturer’s instructions before proceeding.

Next, attach each strip securely to the rafters using screws or nails that are long enough to penetrate through both layers of wood without splitting them. Make sure each strip is level as you go along.

Once all of your furring/lathing strips have been installed and checked for levelness, you can move onto laying down underlayment before finally attaching your metal roofing panels over top.

Installing Roofing Underlayment

One crucial step in this process is installing roofing underlayment. Underlayment acts as a secondary barrier against water infiltration and helps protect your home from leaks.

To install underlayment, start at the bottom of the roof and work your way up towards the peak. Overlap each row by at least six inches to ensure complete coverage.

Use a staple gun or nails with plastic caps to secure each section of underlayment in place.

It’s important not to skimp on quality when selecting an underlayment material; choose one that is durable enough to withstand harsh weather conditions over time.

Applying Metal Roofing Panels

Start at one end of the roof and work your way across, making sure that each panel overlaps with the previous one by at least an inch. Use a chalk line to ensure that each panel is straight and level.

To attach each panel securely, use screws or nails specifically designed for metal roofing installation. These fasteners should be long enough to penetrate through both layers of shingles into solid wood decking below.

When installing metal roofing panels over shingles, it’s important to avoid walking on them as much as possible in order not to damage them or create dents in soft spots beneath old shingles. Instead, use a ladder or scaffolding system for support while working on different sections of your roof.

Metal Panel Attachment Techniques

There are several techniques for attaching metal panels to a shingle roof, including exposed fastener systems and standing seam systems.

Exposed fastener systems involve screwing or nailing the metal panel directly onto the roof deck through pre-drilled holes in each panel. This method is relatively simple and cost-effective but can be prone to leaks over time if not installed correctly.

Standing seam systems involve interlocking seams that connect adjacent panels without any exposed screws or nails. This method provides superior weather resistance but requires more specialized tools and expertise during installation.

Whichever attachment technique you choose, make sure to follow manufacturer instructions carefully for proper spacing of fasteners or seams.

Trimming and Flashing Edges

This is a crucial step in ensuring that your new roof is watertight and secure. First, use tin snips or a circular saw with a metal-cutting blade to trim any excess material from the edges of your roof panels.

Next, install flashing along all of the exposed edges of your roof using roofing nails or screws.

Flashing helps prevent water from seeping under your metal roofing panels by directing it away from vulnerable areas like valleys and seams. You can choose between different types of flashing materials such as aluminum, copper or galvanized steel depending on what suits best for you.

It’s important to make sure that all seams are properly sealed with caulking before installing flashing over them. This will help prevent leaks around these areas in case there are any gaps left after installation.

Installing Ridge and Eave Venting

Without adequate ventilation, moisture can build up in your attic or crawl space, leading to mold growth and structural damage. Ridge vents and eave vents work together to create a continuous flow of air through your roof system.

Ridge vents are installed at the peak of the roofline and allow hot air to escape from the attic or crawl space. Eave vents are installed along the bottom edge of the roofline and allow cool air to enter into this area.

When installing a metal roof over shingles, it’s important not to cover existing ridge or eave venting systems with new materials. Instead, you’ll need to install new venting that works with your metal roofing panels.

Adding Ridge Caps

Ridge caps are essential for sealing off the roof’s peak and preventing water from seeping in. To install ridge caps, start by measuring the length of your roof’s peak and cutting a piece of metal flashing to that length.

Then, fold each side of the flashing down at a 90-degree angle so that they form an L-shape.

Next, place the L-shaped flashing over your roof’s peak with one leg on each side and secure it with screws or nails every few inches along both sides. Make sure to overlap each section slightly as you work your way up towards the top.

Cut another piece of metal flashing into small sections (about 6-8 inches long) and bend them into a U-shape before placing them over each screw or nail head along both sides of your ridge cap installation area. This will help prevent any potential leaks from occurring around these areas.

Safety Tips and Precautions

Before you begin the installation process, make sure that you have all the necessary safety equipment and tools on hand. This includes sturdy work boots with good traction, gloves to protect your hands from sharp edges and debris, eye protection such as goggles or glasses with side shields, and a hard hat to protect your head from falling objects.

It’s also important to use caution when working at heights. Always use proper fall protection equipment such as harnesses and lanyards when working on steep roofs or near edges.

Never attempt roofing work during inclement weather conditions like rain or wind.

If you’re not comfortable working at heights or don’t have experience with roofing installations in general – consider hiring a professional contractor who has both the expertise and equipment needed for safe installation of metal roofs over shingles.

Common Installation Mistakes to Avoid

One of the most common mistakes is failing to properly prepare the roof surface before installing underlayment and metal panels. This can lead to leaks and other issues down the line.

Another mistake is using incorrect attachment techniques or fasteners that are not compatible with your chosen metal roofing material. This can cause damage to both your new roof and existing shingles underneath.

It’s also essential not to overlook proper ventilation during installation, as inadequate venting can result in moisture buildup, which may lead to mold growth or rotting wood decking beneath your new roofing system.

To ensure you get it right when installing a metal roof over shingles, take time for careful planning beforehand and follow manufacturer instructions closely throughout every step of the process.

DIY Vs. Hiring a Professional

If you’re not confident in your abilities or don’t have the necessary tools and equipment, it may be best to hire a professional roofing contractor.

A professional roofer will have the knowledge and skills needed to properly evaluate your existing roof structure, choose appropriate materials, install them correctly while adhering to safety standards. They also carry insurance that protects both themselves and their clients from any accidents or damages that may occur during installation.

On the other hand, if you are experienced with home improvement projects and feel comfortable working on roofs at heights above ground level then doing it yourself could save money on labor costs. However keep in mind that there is still some risk involved when working at heights so make sure you take all necessary precautions such as using proper safety gear like harnesses or scaffolding.

Ultimately whether you decide to do-it-yourself or hire a professional depends on your comfort level with roofing work along with budget constraints.

Maintenance and Upkeep

While metal roofs are durable and long-lasting, they still require some attention to ensure their longevity.

One of the most critical aspects of maintaining a metal roof is keeping it clean. Dirt, debris, and leaves can accumulate on the surface of your roof over time.

If left unchecked, this buildup can trap moisture against the panels or shingles leading to corrosion or rusting.

To prevent this from happening regularly sweep off any debris that accumulates on top of your roofing system using a soft-bristled broom or leaf blower. You may also consider hiring professional cleaning services for more thorough cleaning at least once every year.

Another essential aspect is inspecting for damage after severe weather events such as hailstorms or heavy winds which could cause dents in the panels/shingles leading to leaks if not addressed promptly.

FAQ

Can I install metal roofing directly over shingles?

Yes, you can install metal roofing directly over shingles due to its lightweight nature, making it an ideal material for this purpose.

Do you have to remove shingles before installing a metal roof?

No, you do not have to remove shingles before installing a metal roof, as metal roofs can be installed over existing roofs if local building codes permit it.

Can you put metal roof over shingles without furring strips?

No, it is not recommended to install metal roofing over shingles without furring strips, as it can cause corrosion and reduced moisture venting.

What is the proper method for installing a metal roof over shingles to ensure adequate ventilation?

The proper method for installing a metal roof over shingles is to install it on a batten system or use shingle ventilation with appropriate underlayment, allowing for adequate airflow and ventilation.

What are the potential drawbacks of installing a metal roof over existing shingles?

Potential drawbacks of installing a metal roof over existing shingles include increased weight on the building’s structure, trapped moisture, and potential voiding of the metal roof’s warranty.

How does the installation of a metal roof over shingles impact the overall roof weight and structural integrity?

Installing a metal roof over shingles increases the overall roof weight but generally does not compromise structural integrity due to metal’s lightweight nature and durability.

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