Metal Roof Over Shingles Furring Strips – The Smart Way To A Lasting

Roofing projects can feel like a monumental task, often accompanied by the daunting thought of a complete tear-off. You might be staring at an aging shingle roof, dreaming of the longevity and sleek look of metal, but balking at the labor and disposal costs. What if there was a smarter, more efficient way to achieve that upgrade?

This is where the technique of installing a metal roof over shingles furring strips comes into play. It’s a method gaining popularity among savvy DIYers and homeowners looking for a durable, cost-effective solution. We’re talking about extending your roof’s life, boosting energy efficiency, and giving your home a fresh, modern look—all without the intensive demolition.

In this comprehensive guide, we’ll walk you through everything you need to know about this intelligent re-roofing strategy. We’ll explore why furring strips are essential, what tools and materials you’ll need, and provide a step-by-step breakdown of the installation process. Get ready to transform your roof with confidence and craftsmanship.

Why Choose Metal Over Shingles with Furring Strips?

Deciding on a new roof is a big deal. Choosing to install metal roofing panels over your existing shingles, specifically with the aid of furring strips, offers several compelling advantages for the diligent DIYer.

This method isn’t just a shortcut; it’s a strategic choice for long-term performance.

Benefits of This Roofing Approach

The advantages extend beyond just avoiding a tear-off. You’re making an investment in your home’s future.

• Cost and Time Savings: Eliminating shingle removal saves significantly on labor, dumpster rental, and disposal fees. This directly translates into a more budget-friendly project.
• Enhanced Ventilation: The air gap created by furring strips between the old shingles and the new metal roof allows for continuous airflow. This helps dissipate heat in summer, reducing attic temperatures and lowering cooling costs.
• Moisture Management: This same air gap aids in drying out any potential condensation, protecting both the old shingles and the new metal from moisture-related issues. It’s a natural ventilation system.
• Improved Energy Efficiency: Beyond ventilation, metal roofs reflect solar radiant heat. Combined with the air gap, this can lead to substantial energy savings throughout the year.
• Increased Durability: Metal roofs are renowned for their longevity, often lasting 40-70 years. Installing them over existing shingles adds an extra layer of protection and sound dampening.
• Reduced Landfill Waste: By not tearing off the old shingles, you’re keeping tons of material out of landfills, making it a more environmentally friendly option.

Considerations and Potential Drawbacks

While beneficial, this method isn’t without its points to consider. Be aware of these factors before you start.

• Added Weight: While metal is lighter than many roofing materials, adding it over existing shingles does increase the overall load on your roof structure. Always ensure your roof framing can handle the extra weight.
• Increased Roof Height: The furring strips and metal panels will slightly raise the profile of your roof. This is usually negligible but can be a factor if you have specific aesthetic concerns or clearance issues.
• Potential for Trapped Moisture: If the existing shingle roof is severely damaged or allows significant water penetration, simply covering it without proper assessment can trap moisture. This is why a thorough inspection is paramount.
• Flashings and Transitions: Detailing around chimneys, skylights, and valleys becomes more complex due to the increased roof height. Proper flashing techniques are critical to prevent leaks.

Assessing Your Existing Shingle Roof

Before you even think about cutting furring strips, a thorough inspection of your current shingle roof is non-negotiable. This step is critical for the long-term success of your new metal roof.

Don’t skip this, as hidden issues can compromise your entire project.

Structural Integrity and Damage Inspection

Walk your roof carefully, looking for any signs of trouble. This isn’t just a quick glance.

• Soft Spots: Press down firmly with your foot (or a gloved hand). Any soft, spongy areas indicate rot or compromised decking underneath. These must be repaired before proceeding.
• Visible Leaks: Check for water stains on your attic ceiling or around flashing points. Pinpoint any current or past leak sources.
• Damaged Shingles: Look for curled, cracked, missing, or severely worn shingles. While you’re covering them, extensive damage can still signal underlying issues.
• Decking Condition: If possible, inspect the underside of your roof deck from the attic. Look for water damage, mold, or sagging plywood.

If you find significant rot, structural damage, or widespread leaks, a full tear-off might be the safer and more durable option.

Slope and Drainage Considerations

Metal roofs perform best on certain slopes. Most residential metal roofing requires a minimum pitch.

• Minimum Pitch: Generally, metal roofs need a minimum pitch of 3:12 (3 inches of rise for every 12 inches of run). Check the specifications of your chosen metal roofing panels.
• Drainage Paths: Ensure existing valleys and drainage paths are clear and well-defined. The added height of the furring strips will slightly alter water flow.

A well-drained roof prevents water from pooling, which is crucial for any roofing material.

Essential Tools and Materials for Your Metal Roof Over Shingles Furring Strips Project

Having the right tools and materials on hand makes all the difference in a smooth, safe, and successful installation. Don’t start without a complete inventory.

Think of it as preparing your workshop for a big build, but on your roof.

Must-Have Tools

These are the essentials you’ll need to get the job done right.

• Safety Gear: Fall protection harness and lifeline, sturdy work boots, gloves, eye protection, ear protection. Safety is paramount on the roof.
• Ladders: Extension ladder for roof access, possibly a step ladder for lower sections. Ensure they are stable and rated for your weight plus tools.
• Measuring and Marking: Tape measure, chalk line reel, carpenter’s square, straightedge. Accuracy is key.
• Cutting Tools:
  • Circular saw with a fine-tooth blade for cutting furring strips.
  • A good pair of tin snips (left, right, and straight cut) for metal.
  • Metal cutting shears or an electric metal shear for faster, cleaner cuts on panels.
  • Angle grinder with a metal cutting wheel (use with extreme caution and proper PPE).
• Fastening Tools:
  • Impact driver or heavy-duty drill for driving roofing screws.
  • Drill with various bits for pilot holes if needed.
• Miscellaneous: Utility knife, caulk gun, pry bar, hammer, brooms, magnetic sweeper for metal shavings.

Key Materials for a Durable Installation

Selecting the correct materials ensures your roof performs as expected.

• Furring Strips:
  • Typically 1×3 or 2×2 dimensional lumber.
  • Choose pressure-treated lumber (PT) for enhanced durability and moisture resistance, especially in humid climates.
  • Ensure they are straight and free of major defects.
• Metal Roofing Panels:
  • Corrugated, standing seam, or ribbed panels are common.
  • Consider the gauge (thickness) and coating (e.g., Galvalume, Kynar 500) for longevity and aesthetics.
  • Order extra for cuts and mistakes (usually 10-15% overage).
• Roofing Fasteners:
  • Self-tapping roofing screws with neoprene washers (gaskets).
  • Ensure they are long enough to penetrate the furring strips and securely anchor into the roof rafters.
  • Match the screw color to your metal panels for a cleaner look.
• Flashing and Trim: Ridge caps, gable trim, eave trim, valley flashing, pipe boots, and wall flashing. These pieces are crucial for weatherproofing.
• Closures: Foam or metal strips used to fill the gaps at the eave and ridge, preventing insects and wind-driven rain from entering.
• Underlayment: While optional over existing shingles, a synthetic underlayment can provide an extra layer of protection against moisture and act as a thermal break.
• Sealants: High-quality, UV-resistant roofing caulk compatible with metal for sealing critical joints and penetrations.

Preparing the Roof Deck and Installing Furring Strips

This is where the magic of “metal roof over shingles furring strips” truly begins. Careful preparation and precise installation of the furring strips are critical for a straight, well-ventilated, and long-lasting roof.

Take your time with this step; it sets the foundation for everything else.

Cleaning and Preparing the Existing Roof

Even if you’re not tearing off, a clean slate is essential.

• Clear Debris: Sweep off any loose granules, leaves, twigs, or other debris from the shingle surface. A leaf blower can be very helpful here.
• Address Protrusions: Remove any old vents, satellite dishes, or other elements that won’t be reused. Patch the holes properly with roofing cement and shingle fragments.
• Flatten Curled Shingles: If there are severely curled or lifted shingles, gently try to flatten them or secure them down with a dab of roofing cement. This helps create a flatter plane for the furring strips.

Layout and Marking for Furring Strips

Accuracy here means a straight metal roof. Don’t eyeball it!

1. Establish a Baseline: Start at the eaves. Snap a chalk line parallel to the eave, marking the position for your first furring strip. This needs to be perfectly straight.
2. Locate Rafters: Use a stud finder to locate your roof rafters from inside the attic, if possible, or by careful measurement from the eaves/gable ends. Mark their locations on the shingle surface with chalk lines. These rafters are where you’ll secure your furring strips.
3. Determine Spacing: The spacing of your furring strips depends on your metal panel profile and local building codes. Typically, furring strips are installed horizontally (parallel to the eaves) at 24-inch on-center (OC) spacing for most ribbed or corrugated panels. For standing seam, they might run vertically. Always consult your metal panel manufacturer’s instructions.
4. Mark Subsequent Lines: Once your first line is set, measure up from it and snap parallel chalk lines for each subsequent furring strip. Keep these lines perfectly parallel.

Installing the Furring Strips

This is where the structure comes together. Secure each strip firmly.

1. Start at the Eaves: Install your first furring strip along the eave line you marked. Ensure it’s flush with the edge of the roof or slightly overhanging, depending on your eave trim plan.
2. Secure into Rafters: Drive long, corrosion-resistant screws (typically 2-1/2 to 3 inches) through the furring strip, the existing shingles, and deep into the roof rafters. Use two screws per rafter. The goal is a solid, unmoving attachment.
3. Maintain Straightness: As you install each strip, continually check its alignment with your chalk line. Adjust as needed. A slightly bowed strip will make your metal panels wavy.
4. Create the Air Gap: The furring strips automatically create the ventilation channel. Ensure this gap remains unobstructed.
5. Work Your Way Up: Continue installing furring strips, following your chalk lines, moving upwards towards the ridge.
6. Handle Obstructions: Carefully cut furring strips around chimneys, skylights, and vent pipes. Ensure they provide continuous support around these elements.
7. Ridge and Hips: Install furring strips along the ridge and any hip lines, ensuring they are properly supported to attach the ridge cap later.

Remember, the goal is a flat, stable, and well-supported grid of furring strips ready to receive your metal panels.

Installing Your New Metal Roofing Panels

With the furring strips securely in place, you’re ready for the exciting part: laying down the metal panels. This step requires precision and attention to weatherproofing.

Patience and a good helper will make this process smoother.

Underlayment (Optional but Recommended)

Even over existing shingles, an underlayment offers extra protection.

• Vapor Barrier: A synthetic underlayment acts as an additional vapor barrier and a secondary water shedding surface.
• Thermal Break: It can also provide a thermal break, further enhancing energy efficiency and reducing noise.
• Installation: Roll out the underlayment horizontally, starting at the eave, overlapping according to manufacturer specifications. Secure it with cap nails or staples.

Starting the Panel Installation

The first panel sets the tone for the entire roof.

1. First Panel Placement: Begin at one end of the eave. Align the first metal panel carefully, ensuring it has the correct overhang at the eave and gable end (typically 1-2 inches, consult manufacturer).
2. Secure the First Panel: Drive your self-tapping roofing screws through the designated fastening points on the panel (usually the low ribs for exposed fastener systems) into the furring strips, ensuring they penetrate the rafters below. Do not overtighten; the neoprene washer should be compressed but not squished flat.

Continuing with Panels and Fastening

Consistency is key to a watertight roof.

• Overlapping: Overlap subsequent panels according to the manufacturer’s instructions. This usually involves a side lap where one panel nests into the next.
• Fastener Pattern: Follow the recommended fastener pattern. Typically, screws are placed at every furring strip intersection along the side lap and often in the center of the panel for added rigidity.
• Straightness Check: Periodically check the squareness and straightness of your panels as you work across the roof. A long straightedge or chalk line can help.
• Trimming and Cutting: Use your tin snips or electric shears for precise cuts around hips, valleys, and penetrations. Always wear gloves when handling cut metal edges.
• Magnetic Sweeper: Keep a magnetic sweeper handy to pick up any stray metal shavings. These can rust and stain your new roof or cause punctures if left on the surface.

Ridge Caps and Flashing

These elements are vital for weatherproofing.

• Valley Flashing: Install valley flashing before laying panels in valleys. Overlap flashing pieces correctly and seal with appropriate caulk.
• Pipe Boots: Use specialized rubber boots for vent pipes, sealing them securely to the panel and flashing around the base.
• Chimney and Wall Flashing: Install step flashing and counter-flashing around chimneys and walls where the roof meets a vertical surface.
• Ridge Caps: Once panels are installed on both sides of the ridge, install the ridge cap. Use foam closures under the ridge cap to prevent pests and wind-driven rain. Fasten securely into the furring strips.
• Gable Trim: Install trim along the gable ends to finish the edges and protect them from wind uplift.

Proper installation of flashing is crucial. It’s where most roof leaks occur if not done correctly.

Safety First: Protecting Yourself on the Roof

Working on a roof, especially with metal panels, presents unique hazards. Your safety, and the safety of anyone helping you, must be your absolute top priority.

No roof is worth an injury. Always think safety before action.

• Fall Protection: This is non-negotiable. Use a full-body harness connected to a securely anchored lifeline. Have anchor points rated for fall arrest. Understand how to use the equipment correctly.
• Ladder Safety:
  • Ensure ladders are placed on stable, level ground.
  • Extend ladders at least three feet above the eave.
  • Maintain a 4:1 ratio (for every 4 feet of ladder height, the base should be 1 foot away from the wall).
  • Have someone foot the ladder when you ascend or descend.
• Footwear: Wear sturdy, non-slip work boots with good ankle support. Metal roofs can be slick, even when dry.
• Gloves and Eye Protection: Always wear heavy-duty gloves when handling metal panels to protect against sharp edges and metal shavings. Safety glasses or goggles are a must to protect your eyes from debris and sparks if using cutting tools.
• Tool Safety:
  • Read and understand all power tool manuals.
  • Keep power cords clear of your work area to prevent tripping.
  • Use appropriate blades for cutting metal.
  • Be especially cautious with angle grinders, as they produce sparks and hot debris.
• Weather Awareness: Never work on a roof during rain, high winds, or icy conditions. Wet or windy conditions significantly increase the risk of falls.
• Working with a Partner: Have at least one other person with you. They can help with heavy panels, watch your back, and assist in an emergency.
• Debris Management: Keep your work area on the roof clear of tools, scraps, and fasteners to prevent tripping hazards.
• Sun Protection: Wear appropriate clothing, a hat, and sunscreen, as you’ll be exposed to the sun for extended periods.

If you feel uncomfortable or unsure about any aspect of roof safety, it’s always best to consult with a professional or hire experienced help.

Troubleshooting Common Issues with Metal Roof Over Shingles Furring Strips

Even the most careful DIYer can encounter snags. Knowing how to troubleshoot common problems can save you headaches and costly repairs down the line.

Anticipate challenges and learn how to overcome them like a seasoned pro.

Leaky Fasteners

This is a frequent culprit for leaks in metal roofs.

• Overtightening: If screws are overtightened, the neoprene washer can be damaged, losing its seal. Replace damaged screws, ensuring proper torque.
• Undertightening: Screws that are too loose won’t compress the washer sufficiently, allowing water in. Tighten them until the washer is snug but not bulging.
• Misalignment: Screws driven at an angle or missing the furring strip/rafter can create entry points for water. Remove, seal the old hole with sealant, and re-drive a new screw correctly.
• Aging Washers: Over time, UV exposure can degrade neoprene washers. If your roof is older and leaking, consider replacing screws in affected areas.

Panel Misalignment and Wavy Appearance

A perfectly straight roof is the goal, but sometimes panels can appear wavy.

• Uneven Furring Strips: If your furring strips weren’t perfectly level or straight, the metal panels will follow their contour. This is why careful furring strip installation is crucial. Minor waves might be cosmetic; significant ones could affect drainage.
• Improper Fastening: Panels pulled too tight or fastened incorrectly can warp. Loosen affected screws, realign the panel, and refasten.
• Thermal Expansion: Metal expands and contracts with temperature changes. Ensure panels have proper allowance for movement, especially at overlaps, as per manufacturer guidelines.

Condensation Issues

The air gap from furring strips helps, but condensation can still be a concern.

• Insufficient Ventilation: If your attic has poor ventilation, warm, moist air can rise and condense on the underside of the metal panels, even with the furring strip gap. Ensure adequate soffit and ridge ventilation for your attic space.
• Air Leaks: Seal any air leaks from your living space into the attic (e.g., around light fixtures, plumbing stacks) to reduce moisture-laden air entering the attic.

Noise Reduction

Metal roofs can sometimes be noisy during heavy rain or hail.

• Underlayment: A good quality synthetic underlayment can help dampen sound.
• Insulation: Adding insulation in the attic can further reduce noise transmission.
• Proper Fastening: Securely fastened panels are less likely to rattle. Ensure all screws are snug.

Addressing issues promptly prevents them from escalating into bigger, more expensive problems.

Frequently Asked Questions About Metal Roof Over Shingles Furring Strips

Here are some common questions DIYers ask when considering this roofing method.

Can I install metal roofing directly over old shingles without furring strips?

While technically possible with some metal panel systems, it’s generally not recommended. Installing directly over shingles eliminates the crucial air gap that provides ventilation, prevents condensation, and allows the roof to dry. Without furring strips, you also lose the perfectly flat plane needed for optimal metal roof performance and risk moisture issues.

What type of furring strips should I use?

Most DIYers use 1×3 or 2×2 dimensional lumber. Pressure-treated (PT) lumber is highly recommended for its resistance to rot and insects, ensuring the longevity of your substructure. Always ensure the lumber is straight and free of major defects before installation.

How much ventilation space do I need with furring strips?

The space created by 1×3 or 2×2 furring strips (approximately 3/4 inch or 1-1/2 inches, respectively) is usually sufficient for a ventilation channel. The key is ensuring this channel has clear entry (at the eaves, often through a vented drip edge) and exit points (at the ridge, through a vented ridge cap) to allow for continuous airflow.

What’s the typical lifespan of a metal roof installed this way?

A properly installed metal roof over shingles with furring strips can last 40 to 70 years, often outliving several shingle roofs. The longevity depends on the quality of the metal panels, the fasteners, the installation technique, and proper maintenance. The furring strip method enhances this lifespan by improving ventilation and reducing moisture exposure.

Do I need a permit for this type of roof installation?

Yes, in most jurisdictions, any major roofing project, including installing a new metal roof over existing shingles, requires a building permit. Always check with your local building department before starting work. Permits ensure your project meets local safety and structural codes and can prevent issues when selling your home.

Ready for a Roof That Lasts?

Upgrading to a metal roof using the furring strip method is a smart, strategic choice for any dedicated DIY homeowner. You’re not just putting a new covering on your house; you’re investing in superior longevity, enhanced energy efficiency, and a robust defense against the elements. The “metal roof over shingles furring strips” approach, when done correctly, delivers incredible value.

Remember, the success of this project hinges on careful planning, meticulous execution, and unwavering attention to safety. Don’t rush, measure twice (or thrice!), and always prioritize your well-being on the roof. With the right tools, materials, and a commitment to quality craftsmanship, you’ll soon be enjoying the many benefits of your new, durable metal roof. Stay safe, stay confident, and enjoy the satisfaction of a job well done!

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Jim Boslice

Jim Boslice is a power tool enthusiast who tests, reviews, and shares practical guides to help DIYers and professionals choose the right tools for every project.

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