How to Install Metal Roofing Over Plywood

How to Install Metal Roofing Over Plywood


Installing metal roofing over plywood is a fantastic way to protect your home from the elements while also enhancing its aesthetic appeal.

This type of roofing is known for its durability, longevity, and efficiency in energy conservation.

Whether you’re a seasoned DIY enthusiast or a first-timer, this guide will walk you through the basics of installing metal roofing over plywood, ensuring you have all the knowledge needed to get started.

Let’s dive into the steps and tips to make your roofing project a success!

Materials Needed

Installing metal roofing over plywood is a great way to protect your home. Before you start, make sure you have all the necessary materials. Here’s a list to help you gather everything you need:

  • Metal Roofing Panels: Choose the style and color that best fits your home.
  • Plywood Sheathing: Ensure it’s in good condition and at least 1/2 inch thick.
  • Underlayment: A synthetic underlayment is preferred for better moisture protection.
  • Screws: Use screws specifically designed for metal roofing, often called self-drilling or self-tapping screws.
  • Metal Roofing Flashing: This includes items like ridge caps, and flashing for valleys, chimneys, and vents.
  • Sealant: Use a high-quality, weather-resistant sealant for joints and edges.
  • Tools: Gather a measuring tape, chalk line, metal snips, screw gun, and a hammer.
  • Safety Gear: Safety glasses, gloves, and a hard hat are essential. Also, consider using a safety harness if you’ll be working at heights.

Tip: Always check local building codes and manufacturer’s instructions for specific requirements and recommendations. This will help ensure your roof installation is safe and compliant.

Preparing the Roof

Installing metal roofing over plywood requires careful preparation to ensure a long-lasting and secure installation. Here’s a step-by-step guide to get your roof ready for metal panels:

  1. Inspect the Existing Roof: Check the plywood decking for any signs of damage such as rot or warping. It’s essential that the base is in good condition to support the new roofing material.
  2. Remove Old Roofing Material: If there are any previous layers of roofing material, remove them completely to expose the plywood. This will help you start with a clean slate and prevent any issues related to layering materials.
  3. Clean the Surface: Sweep the plywood to remove all debris, dust, and loose particles. A clean surface ensures better adhesion of the underlayment.
  4. Install Underlayment: Roll out and secure a high-quality roofing underlayment over the plywood to create a barrier against moisture. Make sure to overlap the edges as specified by the manufacturer.
  5. Secure the Edges: Use a staple gun or roofing nails to secure the underlayment, paying extra attention to the edges to prevent wind uplift.
  6. Plan the Layout: Before installing the metal panels, plan the layout based on the size and shape of your roof. This helps in minimizing waste and cutting.
  7. Install Drip Edges: Fit drip edges along the eaves before you lay down the metal panels. This helps in controlling water runoff and protects the underlying materials.

With these steps, your roof will be well-prepared for a new metal covering. Make sure to follow each step carefully for the best results. Happy roofing!

Installing the Underlayment

Before you start laying your metal roofing panels, it’s crucial to install an underlayment over the plywood sheathing. This layer provides an extra barrier against water and helps your roof last longer. Here’s a simple guide to help you through the process:

  1. Choose the Right Underlayment: Opt for a synthetic underlayment for the best durability and moisture protection. It’s more resistant to tearing and can withstand high temperatures, which is ideal under metal roofing.
  2. Prepare the Roof: Make sure the plywood surface is completely clean and dry. Remove any debris, dust, or protruding nails that might damage the underlayment.
  3. Roll Out the First Row: Start at the bottom edge of the roof. Roll out the underlayment horizontally, keeping it taut. Overlap the edge of the roof by about an inch or two to ensure water doesn’t seep underneath.
  4. Secure the Underlayment: Use roofing cap nails or staples to secure the underlayment. Place them at 12 to 16-inch intervals along the edges and in a grid pattern in the center of the strip.
  5. Overlap Each Row: Overlap each subsequent row of underlayment by at least 6 inches over the previous one. This overlap is crucial for creating a water-resistant barrier.
  6. Seal Seams: Use a high-quality roofing tape to seal the seams between the rows of underlayment. This step is vital for preventing water leakage.
  7. Inspect Your Work: Once you’ve installed the underlayment, take a moment to inspect your work. Make sure there are no gaps or loosely attached areas that could let water in.

With the underlayment properly installed, your roof is now ready for the metal panels. This foundation will help ensure your roof performs well and remains leak-free for years to come. Happy roofing!

Laying the Metal Panels

Now that your plywood decking is ready and underlayment is securely placed, it’s time to start laying the metal panels. This step is exciting as you begin to see your new roof take shape! Follow these instructions to ensure your metal roofing is installed correctly and efficiently:

  1. Align the First Panel: Position your first metal roofing panel so that it overhangs the edge of the roof by about 1/2 to 3/4 of an inch. This is crucial for proper water runoff. Make sure it’s square to the roof line.
  2. Secure the Panel: Begin at the bottom of the roof, screw the panel into the plywood using roofing screws. Place screws at the pre-drilled holes or about every 8 inches along the panel’s vertical seam.
  3. Seal the Seams: Apply sealant along the overlapping edge of the next panel before laying it down. This helps create a water-tight barrier.
  4. Overlap the Panels: Place the next panel so that it overlaps the first by about one rib (the raised part of the metal panel). Check alignment and adjust as necessary before securing the panel with screws.
  5. Continue Across the Roof: Repeat the process, ensuring each panel is aligned and overlaps consistently. Use a level or chalk line to keep your lines straight across the roof.
  6. Trimming the Panels: If you reach the end of the roof and a full panel is too wide, you’ll need to trim it. Use metal snips or a metal cutter to cut the panel to size.
  7. Install the Ridge Cap: Once all the panels are in place, install the ridge cap along the peak of the roof. This not only adds a finishing touch but also prevents water from entering under the panels.

By following these steps, you’ll ensure that your metal roof is installed properly and will last for many years. Always remember to wear appropriate safety gear and take your time to achieve the best results.

Sealing and Finishing

Sealing and Finishing

Once you have installed your metal roofing panels over the plywood, it’s crucial to properly seal and finish the installation to ensure it is weatherproof and durable. Here are some straightforward steps to help you complete this phase of your roofing project:

  1. Inspect the Seams: Start by carefully inspecting all the seams between the metal roofing panels. Make sure they overlap correctly according to the manufacturer’s instructions, typically by at least one to two inches.
  2. Apply Sealant: Use a high-quality urethane or silicone-based sealant. Apply it along the seams where the metal panels overlap and at any joints or edges to prevent water infiltration. Be generous but precise with the sealant to avoid any gaps.
  3. Secure the Edges: Fasten the edges of the metal panels to the plywood using appropriate screws or nails. Ensure that these are spaced as recommended by the roofing manufacturer, usually about 12 inches apart.
  4. Install Flashing: Flashing is essential around any protrusions such as vents, chimneys, or skylights, and along the edges where the roof meets a vertical surface like a wall or a dormer. This helps direct water away from these vulnerable areas. Cut the flashing to fit and secure it with fasteners and sealant.
  5. Check for Holes or Gaps: After all components are installed, go over the roof one more time to check for any small holes or gaps in the sealant or between the fasteners and the metal. Apply additional sealant as needed.
  6. Final Inspection: Conduct a final inspection of your roof to ensure everything is securely installed and fully sealed. It’s a good idea to have this inspection on a clear day to ensure no water is currently leaking through any unsealed areas.

By following these steps, you can help ensure that your metal roof over plywood is well-protected against the elements, providing a safe and long-lasting cover for your home. Remember, taking the time to seal and finish your roof properly is crucial for its longevity and effectiveness.

Maintenance Tips: How to Install Metal Roofing Over Plywood

Installing metal roofing over plywood is a great way to protect your home from the elements while providing a durable and long-lasting roof. Here are some easy-to-follow tips to help you with the installation process:

  1. Check Local Building Codes: Before starting your project, make sure to check local building codes to ensure compliance with all requirements regarding roofing installations.
  2. Prepare the Roof: Ensure the plywood decking is in good condition, securely fastened, and free of any moisture or damage. Replace any compromised sections of plywood to avoid future problems.
  3. Install Underlayment: Lay a high-quality roofing underlayment over the plywood to provide an extra layer of protection against water penetration. This is crucial for preventing leaks and extending the life of your roof.
  4. Begin at the Bottom: Start installing your metal roofing panels at the lowest part of the roof. Overlap each panel according to the manufacturer’s instructions to ensure a tight seal.
  5. Secure the Panels: Use appropriate screws or nails to secure the metal panels to the plywood. Make sure to fasten them at the prescribed intervals to keep the roof secure in all weather conditions.
  6. Seal the Edges: Apply a sealant along the edges and joints of the metal panels to prevent water ingress. Pay special attention to any areas that are particularly exposed to the elements.
  7. Inspect Regularly: After installation, regularly inspect your metal roof, especially after severe weather conditions, to ensure that it remains in good condition and that there are no signs of damage or wear.

By following these tips, you’ll be well on your way to successfully installing a metal roof over plywood that will last for many years. Remember, taking the time to do the installation correctly will save you time and money on maintenance in the long run.

Common Mistakes to Avoid When Installing Metal Roofing Over Plywood

Installing metal roofing can be a rewarding project that improves the durability and weather resistance of your home. However, certain common mistakes can undermine the effectiveness of the installation. Here’s what you should watch out for to ensure a successful installation:

  • Not Using a Moisture Barrier: Always install a moisture barrier between the plywood and the metal roofing. This prevents condensation which can lead to wood rot and metal corrosion.
  • Incorrect Fastener Length: Using fasteners that are too short can prevent them from securely attaching the metal panels to the plywood. Conversely, too long fasteners can pierce through the roof entirely. Ensure the length is just right.
  • Ignoring Manufacturer’s Instructions: Different metal roofing systems may have specific requirements for installation. Always follow the manufacturer’s instructions to avoid any potential issues.
  • Improper Overlapping: Metal panels need to be overlapped correctly to ensure water doesn’t seep through the joints. Make sure to overlap the panels as specified by the manufacturer.
  • Poor Alignment: Starting the first panel incorrectly can throw off the alignment of the entire roof. Take extra time to ensure the first panel is perfectly aligned.
  • Not Sealing Edges and Joints: Apply sealant to edges and joints to prevent water penetration, which can lead to leaks.
  • Skipping Safety Measures: Metal roofing installation can be hazardous. Always use safety gear like gloves, safety glasses, and non-slip shoes. Ensure ladders and scaffolds are secure.

By avoiding these common mistakes, you can ensure that your metal roofing installation is secure, effective, and long-lasting. Take your time and don’t rush the process to achieve the best results.


Installing metal roofing over plywood is a practical and rewarding project that can enhance the durability and efficiency of your home. By following the steps outlined, you can ensure a successful installation.

Here are a few actionable tips to keep in mind:

  • Preparation is Key: Ensure the plywood decking is in good condition and properly secured. Any damage or rot should be repaired or replaced to provide a solid foundation for your metal roof.
  • Measure Accurately: Take precise measurements of your roof to avoid material shortages and ensure that your metal panels fit perfectly.
  • Use Quality Materials: Invest in high-quality metal panels, fasteners, and sealants. This will greatly enhance the longevity and performance of your roof.
  • Safety First: Always prioritize safety by using proper protective gear and following safe working practices, especially when working at heights.
  • Seek Professional Help if Needed: If you’re unsure about any step of the process, consulting with or hiring a professional can prevent costly mistakes and ensure that your roof is installed correctly.

By keeping these tips in mind, you’ll be well on your way to successfully installing a metal roof over plywood that will protect and beautify your home for years to come.