Replacing your old shingle roof with a metal roof is an excellent way to improve your home’s appearance and durability. However, installing a metal roof over shingles can be a daunting task, especially if you’re not familiar with roofing work.
Fortunately, with the right tools and materials, you can complete this project yourself. In this detailed guide, we’ll walk you through every step of the process, from preparing your roof to installing the metal panels. We’ll also provide tips and tricks to help ensure a successful and long-lasting installation.
Assessing Roof Conditions: A Prerequisite
Before embarking on the process of installing a metal roof over existing shingles, it is imperative to thoroughly assess the condition of your existing roof. This critical step ensures that your new roof will be installed on a sound and stable foundation, maximizing its longevity and performance.
1. Inspection: A Comprehensive Evaluation
A thorough inspection of your existing roof should include the following steps:
- Visual Examination: Begin by conducting a thorough visual inspection of the roof from both the exterior and interior. Look for signs of damage, such as missing or damaged shingles, rusted flashing, and sagging or broken sheathing.
- Physical Examination: Next, physically examine the roof by carefully stepping on different areas of the roof. Pay attention to any areas that feel soft or spongy, which may indicate underlying structural issues.
- Probe Examination: Using a moisture meter or a simple screwdriver, probe various sections of the roof to check for moisture damage. If the screwdriver easily penetrates the roof, it may indicate rot or deterioration.
2. Condition Assessment
After completing the inspection, assess the condition of your roof based on the following criteria:
| Condition | Characteristics |
|---|---|
| Good | Minimal to no damage, sound sheathing, no signs of moisture |
| Fair | Some damage present, such as missing shingles or minor flashing issues, some signs of moisture |
| Poor | Significant damage, such as broken or sagging sheathing, extensive moisture damage, requires repairs or replacement |
3. Considerations for Metal Roof Installation
Based on the condition assessment, determine the feasibility of installing a metal roof over your existing shingles:
- Good Condition: If your roof is in good condition, it can typically support a metal roof installation without requiring extensive repairs.
- Fair Condition: Roofs in fair condition may require some repairs, such as replacing damaged shingles or fixing flashing issues, before installing a metal roof.
- Poor Condition: Roofs in poor condition may not be suitable for a metal roof installation and may require significant repairs or even replacement before considering a metal roof.
Removal of Existing Asphalt Shingles
To install metal roofing over existing shingles, the first step is to remove the asphalt shingles. This can be a time-consuming and labor-intensive process, but it’s essential to do it properly to ensure a long-lasting and durable metal roof.
Tools You’ll Need
- Roofing shovel or pry bar
- Hammer or nail gun
- Utility knife
- Safety glasses
- Gloves
- Ladder
Safety Precautions
- Wear appropriate safety gear, including safety glasses and gloves.
- Use a ladder carefully and have someone hold it for stability if possible.
- Be aware of sharp objects and nails.
- If possible, remove the shingles on a dry and windless day.
Step-by-Step Instructions
- Remove starter strip: Use a pry bar or roofing shovel to carefully remove the starter strip along the eaves. Avoid damaging the drip edge.
- Loosen the first row of shingles: Using a pry bar, gently loosen the bottom row of shingles and slide them up slightly to expose the nails.
- Remove nails: Use a nail gun or hammer to carefully pull out the nails holding the shingles in place. Be careful not to damage the underlying roof deck.
- Slide up and remove shingles: Once the nails are removed, slide the first row of shingles up and off the roof. Continue this process for the remaining rows of shingles.
Tips
- Start by working in the center of the roof and gradually move towards the edges to prevent the shingles from sliding down.
- Use a utility knife to cut through any stubborn shingles that cannot be pried off.
- Be patient and take your time. Removing shingles is a tedious process, but it’s important to do it carefully to avoid damaging the underlying roof deck.
Securing Metal Panels with Roofing Screws
Roofing screws are the primary method for securing metal panels to the underlying roof structure. These screws come in a variety of sizes and thread configurations to suit different panel gauges and applications.
When selecting roofing screws, it’s important to consider the following factors:
- Panel gauge: Thicker panels require larger screws with higher thread counts.
- Roofing type: Screws for metal over shingles will be shorter than those used for other roofing types.
- Climate: Screws with protective coatings are recommended for areas with high moisture or exposure to salt or corrosive elements.
- Head style: The most common head styles are hex, flat, and pan head. Choose a head style that provides adequate contact with the drill driver and accommodates any trim or flashing.
Screw Placement and Pattern
The placement and pattern of roofing screws are crucial for proper panel attachment and structural integrity.
Side laps: Screws should be driven through the side laps of the panels, typically 12 inches on center.
Top laps: For panels with interlocking top laps, screws should be driven through the top crown of the panel.
End laps: Screws should be driven through the end laps of the panels, avoiding the inside ribs.
Valleys and ridges: Use larger screws with higher thread counts for valleys and ridges.
| Screw Size | Thread Count | Panel Gauge | Application |
|---|---|---|---|
| #12 | 14 | 29-26 | Side laps, thin panels |
| #12 | 17 | 24-22 | Top laps, valleys, ridges |
| #14 | 14 | 29-26 | Side laps, thick panels |
| #14 | 17 | 24-22 | Top laps, valleys, ridges |
Overlapping and Interlocking Panels for Weatherproofing
Overlapping and interlocking panels are crucial design elements in metal roof systems over shingles. They provide an extra layer of protection against moisture penetration and ensure the durability of the roof.
Overlapping Panels:
Overlapping panels are installed in a horizontal or vertical arrangement, with each panel extending over the previous one. The overlap area is typically several inches wide and is sealed with mastic, tape, or other weatherproofing materials. This creates a double layer of protection, preventing water from seeping into the roof structure.
Interlocking Panels:
Interlocking panels feature a unique design that allows them to fit together tightly, forming a nearly seamless connection. These panels have interlocking edges that engage with each other, creating a watertight seal. Interlocking panels provide enhanced weatherproofing compared to overlapping panels and are often used in areas with heavy rain or snow.
Weatherproofing Measures:
In addition to overlapping and interlocking panels, several other weatherproofing measures are employed during a metal roof installation. These include:
| Measure | Description |
|---|---|
| Sealants and Mastics | Applied between panel joints and seams to fill gaps and prevent water infiltration. |
| Flashings | Metal strips installed around chimneys, vents, and other roof penetrations to seal against moisture. |
| Underlayment | A waterproof membrane installed beneath the metal panels to provide an additional layer of protection. |
These measures work together to create a highly weatherproof system that protects your home from the elements for many years to come.
Caulking and Sealing for Optimal Waterproofing
1. Inspect the Metal Roofing System
Check the metal roofing system thoroughly for any penetrations, such as screws, bolts, or seams. These areas will need to be properly sealed to prevent water infiltration.
2. Clean the Surface
Clean the surface of the metal roofing system thoroughly using a mild detergent and a soft cloth. Remove any dirt, dust, or debris that could interfere with the adhesion of the caulking or sealant.
3. Apply a Primer
In some cases, a primer may be necessary to improve the adhesion of the caulk or sealant. Consult the manufacturer’s instructions to determine if a primer is recommended for your particular system.
4. Apply Caulk
Apply a bead of high-quality construction sealant around the penetrations and seams in the metal roofing system. Use a seal that is compatible with the type of metal used for the roofing.
5. Smooth the Caulk
Smooth the caulk using a caulk smoothing tool or your finger. Ensure that the caulk is evenly distributed and pressed into the gap between the metal and the penetration or seam.
6. Seal Gaps and Edges
Use a sealant that is specifically designed for sealing gaps and edges around skylights, vents, and other protrusions on the metal roofing system. Apply the sealant according to the manufacturer’s instructions.
7. Flashings and Trim
Install flashing and trim components around chimneys, vents, and other protrusions to direct water away from the vulnerable areas. Use appropriate sealants and fasteners to secure these components and prevent leaks.
| Flashing Type | Purpose |
|---|---|
| Step Flashing | Seals the junction between roofing material and vertical surfaces |
| Counter Flashing | Prevents water infiltration at the top edge of flashing |
| Base Flashing | Provides a weatherproof seal at the base of walls or chimneys |
| Valley Flashing | Protects internal angles where two roof slopes meet |
Trimming and Flashing for a Finished Look
Cutting and Fitting Ridge Cap
Cut the ridge cap to the length of the roof ridge, ensuring it overhangs the edges by several inches. Use a metal shear or nibbler for precise cuts. Fit the ridge cap over the purlins, ensuring it is level and aligned with the roof peak.
Installing Ridge Flashing
Place ridge flashing over the ridge cap, overlapping it by at least 6 inches. Secure the flashing to the purlins using roofing nails or screws. Use a sealant to seal any gaps between the flashing and the ridge cap.
Trimming and Fitting Rake Flashing
Cut the rake flashing to fit the length of the roof edge. Overhang it by several inches at the bottom. Bend the flashing at a 90-degree angle to form a flange for nailing.
Installing Rake Flashing
Install the rake flashing along the roof edge, overlapping it with the ridge flashing by at least 6 inches. Nail or screw the flashing to the roof decking.
Inserting Collar Flashings Around Pipes
Cut a circular opening in the metal roofing around pipes or vents. Place a collar flashing around the pipe and secure it to the roofing with roofing nails or screws. Seal around the edges with a sealant.
Installing Valley Flashing
Cut valley flashing to fit the length of the valley. Overlap the flashing by at least 6 inches. Bend the flashing at a 90-degree angle to form a flange for nailing.
Installing Valley Flashing (Wrap Step)
Install the valley flashing along the valley, overlapping it with the ridge flashing and rake flashing. Nail or screw the flashing to the roof decking, being careful not to penetrate the underlying shingles.
Finishing Touches
Apply a sealant to all seams and overlaps in the flashing to ensure a watertight seal. Inspect the entire roof to ensure all trim and flashing is secure and professionally installed.
Maintenance and Longevity of the Metal Roof
Structural Maintenance
Metal roofs are known for their durability and longevity, lasting up to 50 years or more. However, proper maintenance is essential to ensure their optimal performance and lifespan. Regularly inspect the roof for any signs of damage, such as dents, punctures, or loose screws. Address any issues promptly to prevent further deterioration.
Corrosion Prevention
Metal roofs are typically made of corrosion-resistant materials like galvanized steel or aluminum. However, exposure to moisture and chemicals can cause rust or corrosion over time. To prevent this, regularly clean the roof with a mild detergent and water solution. Avoid using harsh chemicals or abrasive cleaners, as these can damage the protective coating.
Painting and Recoating
Over time, the paint or coating on a metal roof may fade or deteriorate. To maintain its appearance and longevity, consider repainting or recoating the roof every 15-20 years. Use a high-quality paint or coating specifically designed for metal roofs to ensure proper adhesion and protection.
Cleaning and Gutter Maintenance
Debris, leaves, and dirt can accumulate on the metal roof and in the gutters. Regularly clean the roof and gutters to prevent blockages and water damage. Use a soft brush or a leaf blower to remove debris and inspect the gutters for clogs or leaks.
Ventilation
Proper ventilation is crucial for a metal roof. Heat buildup under the roof can cause premature fading, corrosion, and damage to the roofing materials. Ensure adequate ventilation by installing ridge vents or soffit vents to allow air to circulate and dissipate moisture.
Snow and Ice Removal
In areas with heavy snowfall, it’s important to remove snow and ice from the roof to prevent excessive weight and potential damage. Use a snow rake or broom to carefully remove snow and avoid using sharp objects that could scratch the metal.
Professional Inspections
Consider scheduling regular professional inspections by a qualified roofing contractor. Inspections can identify any potential issues early on, allowing for timely repairs and maintenance to extend the roof’s lifespan.
Warranty Coverage
Most metal roofs come with a manufacturer’s warranty. Familiarize yourself with the warranty terms and conditions to understand the coverage and limitations. If any issues arise within the warranty period, contact the manufacturer or a certified installer to file a claim.
Life Expectancy
The life expectancy of a metal roof varies depending on the type of metal, thickness, and maintenance practices. On average, metal roofs can last for 50 years or more, with proper care and regular maintenance. By following these tips, you can ensure the longevity and performance of your metal roof, protecting your home from the elements for decades to come.
Enhancing Curb Appeal with Metal Roofing
Metal roofing offers a number of benefits that can enhance the curb appeal of your home, including:
1. Durability: Metal roofing is extremely durable and can last for 50 years or more. This means that you won’t have to worry about replacing your roof for many years to come.
2. Low maintenance: Metal roofing is also very low maintenance. Unlike other types of roofing, metal roofing doesn’t need to be painted or stained. Just washing with water is enough.
3. Energy efficiency: Metal roofing can help you save money on your energy bills. The reflective surface of metal roofing helps to keep your home cooler in the summer and warmer in the winter.
4. Fire resistance: Metal roofing is fire resistant, which can help to protect your home in the event of a fire.
5. Variety of styles: Metal roofing is available in a variety of styles, so you can find the perfect look for your home.
6. Increased property value: Metal roofing can increase the value of your home. This is because metal roofing is a durable and attractive material that can make your home more appealing to potential buyers.
7. Environmental friendliness: Metal roofing is an environmentally friendly option. Metal roofing is made from recycled materials and can be recycled at the end of its lifespan.
8. Noise reduction: Metal roofing can help to reduce noise pollution. The thick panels of metal roofing absorb sound, which can make your home more peaceful and quiet.
9. Algae resistance: Metal roofing is algae resistant, which means that you won’t have to worry about unsightly black streaks on your roof.
10. Lightweight: Metal roofing is lightweight, which can make it easier to install and can reduce the load on your home’s structure.
| Metal Roofing Types | Description |
|---|---|
| Standing seam | Metal panels that are attached to the roof deck with vertical seams. |
| Corrugated | Metal panels that have a wavy pattern. |
| Metal shingles | Metal panels that are designed to look like traditional shingles. |
How to Put Metal Roof Over Shingles
Installing a metal roof over shingles can be a cost-effective way to extend the life of your roof and improve its curb appeal. Here are the steps involved:
1. **Inspect the Shingles**. First, inspect the existing shingles for any damage or deterioration. If the shingles are in good condition, you can proceed with the installation. If there are any damaged shingles, they should be repaired or replaced before installing the metal roof.
2. **Install Roofing Felt**. Next, install roofing felt over the shingles to provide a barrier between the shingles and the metal roof. Roofing felt is a water-resistant material that helps to prevent leaks.
3. **Install Battens**. Battens are narrow strips of wood that are installed over the roofing felt. They provide a solid surface for the metal roof to be installed on.
4. **Install Metal Roof Panels**. Starting at the bottom edge of the roof, install the metal roof panels one by one. Overlap the panels slightly and secure them with screws or nails.
5. **Trim and Seal**. Once the metal roof panels are installed, trim any excess material around the edges of the roof. Seal any gaps or openings with caulk or sealant.
People Also Ask
How much does it cost to put a metal roof over shingles?
The cost of installing a metal roof over shingles varies depending on the size of the roof, the type of metal used, and the complexity of the installation. On average, the cost ranges from $7 to $12 per square foot.
Can I install a metal roof over shingles myself?
Installing a metal roof over shingles is a complex process that requires specialized tools and skills. It is not recommended to attempt this project yourself unless you have experience in roofing.
How long does a metal roof last?
Metal roofs are durable and can last for 50 years or more. They are resistant to fire, wind, and hail, and they do not require as much maintenance as other types of roofing materials.
