Steel roofing is a durable, energy-efficient, and long-lasting roofing solution that offers superior protection against harsh weather. If you have an existing asphalt shingle roof that is nearing the end of its lifespan, you may be considering installing steel roofing over shingles rather than tearing off the old roof. This method can save time, reduce labor costs, and minimize waste.
In this comprehensive guide, we will walk you through how to install steel roofing over shingles, including the materials you’ll need, preparation steps, installation techniques, and expert tips to ensure a successful project.
Can You Install Steel Roofing Over Shingles?
Yes, in many cases, you can install steel roofing over shingles without removing the old roofing material. However, there are some key considerations:
✔ Local Building Codes – Check with your local building department to ensure that installing a steel roof over shingles is allowed in your area. Some codes restrict multiple layers of roofing.
✔ Roof Condition – The existing shingle roof must be in relatively good condition. If there are soft spots, rotting wood, or significant structural damage, a tear-off may be necessary.
✔ Weight Considerations – Steel roofing is lightweight, but if your roof already has multiple layers of shingles, consult a professional to ensure that your home’s structure can support the added weight.
✔ Flat and Even Surface – A layer of furring strips (battens) should be installed over the shingles to create a flat, ventilated surface for the steel panels.
Materials and Tools Needed
Before you start, gather the necessary materials and tools for a successful installation:
Materials
✔ Steel Roofing Panels – Choose a style that complements your home, such as standing seam or corrugated panels.
✔ Furring Strips (1×4 or 2×4 Lumber) – These create an even surface and allow for proper ventilation beneath the steel roofing.
✔ Fasteners (Screws with Rubber Washers) – These help secure the steel panels while preventing leaks.
✔ Synthetic Roofing Underlayment – Acts as a moisture barrier between the shingles and steel roofing.
✔ Ridge Cap – Covers the roof peak to provide a finished look and prevent leaks.
✔ Closure Strips and Sealant – Used to seal gaps and improve weather resistance.
✔ Drip Edge – Helps direct water away from the roof edges.
Tools
✔ Cordless Drill – For securing screws.
✔ Tin Snips or Metal Cutting Saw – To cut steel panels to size.
✔ Measuring Tape and Chalk Line – For precise measurements and alignment.
✔ Ladder and Safety Harness – Ensures a safe working environment.
✔ Roofing Gloves and Eye Protection – Provides safety during handling and installation.
Step-by-Step Guide on How to Install Steel Roofing Over Shingles
Step 1: Inspect the Existing Roof
Before you begin the installation process, it’s crucial to inspect the existing shingle roof to ensure it is in good condition. Walk around the house and look for any sagging areas, missing shingles, or signs of water damage. Use a ladder to get a closer look at the roof’s surface, paying particular attention to soft spots that could indicate rotting plywood underneath.
If you notice any structural damage, such as weak roof decking or deteriorated trusses, it’s best to repair these issues before proceeding. A solid and stable foundation is essential for supporting the additional weight of the steel roofing. If the existing roof is severely damaged, a complete tear-off may be necessary to prevent future problems.
In addition to physical inspection, check with local building codes to ensure that installing steel roofing over shingles is allowed in your area. Some regulations limit the number of roofing layers permitted on a home, so it’s important to verify compliance before moving forward.
Step 2: Install a Moisture Barrier
Even though asphalt shingles provide some level of water resistance, installing a synthetic roofing underlayment is a critical step in preventing moisture-related problems. Over time, condensation can form beneath steel roofing due to temperature fluctuations, which may lead to mold growth, rot, or rust.
To install the underlayment:
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Start at the lowest edge of the roof and unroll the synthetic underlayment horizontally.
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Overlap each row by at least six inches to ensure continuous coverage and prevent leaks.
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Secure the underlayment with cap nails or staples every 12 inches along the edges and every 24 inches in the middle.
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Smooth out any wrinkles or air pockets to create a flat surface, as bumps could affect the installation of the steel panels.
Taking the time to install a moisture barrier properly will help extend the life of your steel roofing over shingles and provide added protection against water infiltration.
Step 3: Attach Furring Strips (Batten System)
Installing furring strips, also known as a batten system, is essential to creating a level surface for the steel panels. Without this step, the steel roofing may conform to the uneven shape of the existing shingles, leading to an unprofessional appearance and reduced durability.
To install the batten system:
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Use 1×4 or 2×4 wooden furring strips, which provide the necessary support for the steel panels.
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Place the strips horizontally across the roof, spacing them 16 to 24 inches apart, depending on the panel specifications.
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Secure each furring strip using long wood screws that penetrate the roof deck and reach into the rafters for maximum strength.
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Double-check the alignment of the strips with a level and chalk line to ensure that the steel roofing will be installed evenly.
In addition to leveling the roof surface, the furring strips create a ventilation gap between the steel panels and the existing shingles. This ventilation helps reduce heat buildup during summer and prevents condensation from forming beneath the metal roof.
Step 4: Measure and Cut Steel Panels
Before securing any panels, take accurate measurements of the roof to determine how many steel roofing panels are needed. Use a measuring tape and chalk line to mark the correct dimensions on each panel.
To cut the panels to size:
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Use tin snips for small cuts or a metal cutting circular saw for larger sections.
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Always wear protective gloves and eye protection, as cutting steel can produce sharp edges and flying debris.
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Cut the panels on a stable, flat surface to ensure accuracy and prevent damage to the material.
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Label each panel according to its placement on the roof to avoid confusion during installation.
Properly measured and cut panels will ensure a smooth installation and prevent the need for unnecessary adjustments later.
Step 5: Install the First Steel Panel
Installing the first panel correctly is crucial, as it sets the foundation for the entire roof.
To begin:
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Start at the lowest edge of the roof and place the first panel in position, ensuring it overhangs the edge by at least 1 inch to allow for water runoff.
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Align the panel carefully with the edge of the roof to keep it straight. Use a chalk line to guide placement.
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Secure the panel using roofing screws with rubber washers to prevent leaks.
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Place the screws along the raised ridges of the panel, spacing them every 12 to 24 inches to ensure a firm hold.
Be sure not to overtighten the screws, as this can warp the metal. A snug fit is ideal to allow for natural expansion and contraction.
Step 6: Overlap and Secure Additional Panels
Steel roofing panels are designed to overlap for added protection against water infiltration.
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Align each new panel so that it overlaps the adjacent one by at least one ridge.
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Secure the overlapping panels with screws along the seam to create a watertight seal.
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Work methodically across the roof, checking alignment regularly to prevent any shifting or misalignment.
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Continue installing panels until the entire roof is covered.
Ensuring proper panel overlap will improve the longevity and performance of your steel roofing over shingles.
Step 7: Install the Ridge Cap
The ridge cap is installed along the peak of the roof to seal the top and prevent water from entering.
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Lay the ridge cap over the peak, ensuring it overlaps both sides of the steel panels evenly.
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Use closure strips and sealant to fill any gaps and prevent wind-driven rain or pests from entering.
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Secure the ridge cap with screws placed every 12 inches along both edges.
Proper installation of the ridge cap is essential for maintaining a leak-free steel roof.
Step 8: Install Flashing and Drip Edge
To ensure complete water protection, install flashing around roof penetrations such as chimneys, skylights, and vents.
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Cut the flashing material to fit around the obstacle.
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Use roofing sealant to create a waterproof barrier between the flashing and the steel panels.
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Secure the flashing with screws or nails, ensuring a tight fit.
The drip edge should also be installed along the eaves and gables to direct water away from the roof’s edge and prevent damage to the structure.
Step 9: Perform a Final Inspection
Once all panels, flashing, and trim pieces are installed, conduct a thorough final inspection.
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Walk around the property and examine the roof from different angles.
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Look for loose screws, misaligned panels, or gaps that need sealing.
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Ensure all fasteners are properly secured but not overtightened.
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Remove any metal shavings or debris that could cause rusting over time.
After confirming that everything is properly installed, your steel roofing over shingles is complete and ready to provide years of durable, weather-resistant protection.
Benefits of Installing Steel Roofing Over Shingles
✔ Cost Savings – Avoids tear-off labor costs, making installation more affordable.
✔ Reduced Waste – Keeps old shingles out of landfills, making it an environmentally friendly option.
✔ Improved Energy Efficiency – Reflects solar heat, reducing cooling costs in summer.
✔ Increased Home Value – Adds curb appeal and enhances durability, increasing property value.
✔ Weather Resistance – Protects against wind, rain, hail, and snow for decades.
Common Mistakes to Avoid
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Skipping the Furring Strips – Without a batten system, steel panels may conform to uneven shingles, reducing longevity.
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Overtightening Screws – This can warp the panels and compromise their waterproofing ability.
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Improper Overlaps – Incorrect panel overlap can cause leaks and reduce wind resistance.
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Neglecting Roof Ventilation – Poor airflow can lead to moisture buildup and damage.
Final Thoughts
Installing steel roofing over shingles is an excellent way to upgrade your home without the hassle of removing the old roof. By following the proper installation steps, using high-quality materials, and ensuring proper ventilation, you can enjoy a long-lasting, energy-efficient, and durable steel roof.
If you’re unsure about any step of the process, consulting with a professional roofing contractor can help ensure a safe and efficient installation. Investing in a steel roof today means enjoying superior protection and cost savings for decades to come.
