Are you considering a metal roof for your home, but you’re not sure if it’s possible to install it over your existing shingles? The good news is that it is possible to install a metal roof over shingles, and it can be a great way to update the look of your home while also protecting it from the elements.
There are several reasons why you might want to consider installing a metal roof over shingles. Metal roofs are more durable than shingle roofs, and they can last for 50 years or more. They are also more resistant to fire, wind, and hail damage. Additionally, metal roofs can be more energy-efficient than shingle roofs, as they reflect the sun’s heat away from your home in the summer and help to keep it warm in the winter.
If you’re interested in installing a metal roof over shingles, there are a few things you need to keep in mind. First, you’ll need to make sure that your roof is strong enough to support the weight of the metal roof. Second, you’ll need to install a layer of underlayment between the shingles and the metal roof. This underlayment will help to protect the shingles from moisture and will also help to reduce noise from the metal roof. Finally, you’ll need to choose the right type of metal roof for your home. There are several different types of metal roofs available, so you’ll need to do some research to find the one that’s right for you.
Preparation of the Roof Surface
Inspecting the Roof Sheathing
Before installing metal roofing over shingles, it is essential to thoroughly inspect the underlying roof sheathing. This involves removing several shingles in various locations to assess the condition of the sheathing, including checking for any signs of rot, buckling, or moisture damage. Identifying and repairing any existing issues will provide a solid foundation for the metal roof and prevent potential problems down the road.
Removing Loose or Damaged Shingles
Once the roof sheathing has been inspected, it is crucial to remove any loose or damaged shingles to create a smooth and level surface for the metal roofing. This process can be time-consuming but is essential to ensure proper adhesion and prevent future leaks. Using a pry bar or shingle remover, carefully lift and detach the loose shingles, taking care to avoid damaging the underlying sheathing.
Installing Roofing Felt
After removing loose shingles, install a layer of roofing felt over the entire roof surface. Roofing felt, also known as tar paper, acts as a water-resistant barrier between the sheathing and the metal roofing. Unroll the felt parallel to the eaves, ensuring an overlap of at least 6 inches between each roll. Secure the felt using roofing nails spaced 6-12 inches apart. Proper installation of roofing felt will provide an additional layer of protection against moisture and help prevent leaks.
| Roofing Felt Installation |
|—|—|
| Roll Width | 36 inches |
| Overlap | 6 inches |
| Nail Spacing | 6-12 inches |
| Nail Size | 1 1/4 inches |
Removing Damaged or Loose Shingles
Before installing a metal roof, it’s crucial to remove any damaged or loose shingles from the underlying roof structure. This step ensures a smooth and secure installation, preventing water leaks and other potential issues down the road.
Materials Required:
| Item | Quantity |
|---|---|
| Pry bar | 1 |
| Hammer | 1 |
| Safety glasses | 1 pair |
| Work gloves | 1 pair |
| Ladder | 1 |
Safety Precautions:
- Wear safety glasses and work gloves to protect yourself from debris and sharp nails.
- Use a sturdy ladder and maintain proper footing while working on the roof.
- Be cautious of exposed nails and sharp edges of shingles.
Once you have assessed the roof and gathered the necessary materials, follow these steps to remove damaged shingles:
- Identify the damaged or loose shingles: Inspect the roof for any visible damage, such as cracked, missing, or curled shingles.
- Remove the loose shingles: Use a pry bar to carefully lift the loose shingles from the roof deck. If the shingles are nailed down, gently tap the pry bar under the nail and pry it up.
- Remove damaged shingles: For damaged shingles, you may need to use a hammer to break them into smaller pieces. Remove all pieces of the damaged shingle from the roof deck.
- Clean the exposed roof deck: Once you have removed all the damaged or loose shingles, use a broom or brush to clean any debris or dust from the exposed roof deck.
Installing a Roof Membrane
After the old shingles have been removed, a roof membrane should be installed to create a weather-resistant barrier between the decking and the metal roofing. This membrane typically consists of a synthetic material, such as ethylene propylene diene monomer (EPDM) or polyisobutylene (PIB), which is rolled out over the decking and secured with adhesive strips or nails. The membrane should overlap the edges of the decking by at least 6 inches and be sealed with flashing tape at any seams or penetrations.
In addition to providing weather resistance, a roof membrane can also act as a sound dampener, reducing the noise of rain or hail hitting the roof. It can also help to regulate the temperature in the attic, by reflecting heat away in the summer and retaining heat in the winter.
Here is a step-by-step guide to installing a roof membrane:
- Roll out the membrane over the decking, starting at the eaves and working your way up the roof.
- Overlap the edges of the membrane by at least 6 inches and secure them with adhesive strips or nails.
- Seal any seams or penetrations with flashing tape.
- Cut the membrane around any chimneys, vents, or other roof penetrations.
- Flash the penetrations with metal or plastic flashing and seal the edges with caulk or sealant.
| Material | Pros | Cons |
|---|---|---|
| EPDM | Durable, UV-resistant, and fire-resistant | Can be more expensive than other materials |
| PIB | Lightweight, flexible, and easy to install | Not as durable as EPDM |
Selecting the Right Metal Roofing Panels
When selecting metal roofing panels for your project, there are several factors to consider to ensure optimal performance and aesthetics:
Material Type:
| Material | Benefits | Drawbacks |
|---|---|---|
| Galvalume | Lightweight, durable, corrosion-resistant | Higher cost |
| Aluminum | Lightweight, corrosion-resistant, non-magnetic | Prone to denting |
| Copper | Durable, corrosion-resistant, aesthetically pleasing | Expensive, can oxidize over time |
| Zinc | Lightweight, corrosion-resistant, self-healing | Limited color options, can be brittle |
Profile:
Choose a profile that complements your home’s architectural style and provides the desired coverage and protection from the elements. Common profiles include standing seam, corrugated, and tile-style panels.
Finish:
The finish of your metal roofing panels will determine their appearance and durability. Consider options such as paint, Kynar 500 PVDF coating, or bare metal.
Thickness and Gauge:
Panel thickness is measured in millimeters or gauges. Thicker panels (e.g., 24 gauge) offer better durability, while thinner panels (e.g., 32 gauge) are more budget-friendly. Consult a roofing professional to determine the appropriate thickness for your climate and application.
Cutting and Installing the Metal Roofing Panels
1. Measure and cut the metal roofing panels to the desired length. Use a circular saw or a metal shear for this task.
2. Install the drip edge along the lower edge of the roof. Secure it with screws.
3. Install the underlayment over the drip edge and shingles.
4. Start installing the metal roofing panels from the bottom of the roof and work your way up.
Overlapping the Metal Roofing Panels
When installing the metal roofing panels, overlap the panels by 6 to 12 inches. The overlap should be in the direction of water flow.
Secure the panels to the roof with screws. Use a screw gun for this task.
| Screw Type | Recommended Length |
|---|---|
| Self-tapping screws | 1-1/2 inches |
| Hex-head screws | 2 inches |
The number of screws required per panel will vary depending on the size of the panel and the wind load in your area.
Once the metal roofing panels are installed, seal the overlaps with a roofing sealant. This will help to prevent water leaks.
Securing the Metal Roofing Panels
Once the underlayment is installed, it’s time to secure the metal roofing panels. This process involves several steps to ensure a sturdy and leak-proof installation.
6. Screw Down the Panels
The final step in securing the metal roofing panels is to screw them down into the purlins or roof sheathing. Use self-drilling screws that are specifically designed for metal roofing. Start at the bottom of the roof and work your way up. Align the panels and fasten them into place, making sure to drive the screws straight into the underlying material. Use a screw gun or impact driver to save time and effort.
Screw spacing will vary depending on the panel type and local building codes. Generally, it’s recommended to place screws every 4 to 6 inches along the side laps and every 12 to 18 inches along the end laps. For areas with high winds or snow loads, you may need to use closer spacing.
Here’s a table summarizing the recommended screw spacing:
| Panel Type | Side Lap Screw Spacing | End Lap Screw Spacing |
|---|---|---|
| Standing Seam | 4 inches | 12 inches |
| R-Panel | 6 inches | 18 inches |
| Corrugated | 4 inches | 12 inches |
Note that these are general recommendations, and you should always follow the manufacturer’s instructions for specific panel types and installation conditions.
Trimming and Finishing the Roof Edges
Once the metal panels have been installed, it’s time to trim and finish the roof edges to complete the installation. This involves adding trim pieces to cover any exposed edges of the panels, as well as installing gutters and downspouts to manage rainwater.
Fascia
The fascia is a horizontal trim piece that runs along the eaves of the roof, covering the exposed ends of the metal panels. It also provides a base for the gutters.
Soffit
The soffit is a trim piece that covers the underside of the roof overhang, between the fascia and the roof deck. It helps to improve ventilation and prevents pests from entering the attic.
Drip Edge
The drip edge is a strip of metal that is installed along the eaves of the roof to prevent water from dripping behind the fascia and into the attic. It also helps to direct water away from the foundation of the house.
Ridge Cap
The ridge cap is a trim piece that covers the peak of the roof, where two roof surfaces meet. It helps to keep water out of the roof system and prevents leaks.
Gutter and Downspouts
Gutters and downspouts are essential for managing rainwater and preventing water damage to the home. The gutter is a horizontal trough that collects rainwater from the roof, while the downspout is a vertical pipe that carries the water away from the house and into the ground.
Installing Gutter and Downspouts in Detail
| Step | Description |
|---|---|
| 1 | Determine the gutter size and number of downspouts needed based on the roof size and slope. |
| 2 | Mark the location of the gutters and downspouts on the fascia and roof. |
| 3 | Install gutter hangers to the fascia, spacing them evenly apart. |
| 4 | Place the gutters on the hangers and snap them into place. |
| 5 | Install downspout brackets to the side of the house. |
| 6 | Place the downspouts on the brackets and secure them. |
| 7 | Connect the downspouts to the gutters using downspout elbows and extensions as needed. |
| 8 | Extend the downspouts down to the ground and install splash blocks to direct the water away from the foundation. |
Sealing and Weatherproofing the Roof
1. Applying Sealant Tape
Apply high-quality sealant tape along the joints between the metal roof panels and the shingles. This will prevent moisture from penetrating the roof and causing leaks.
2. Installing Eave Flashing
Install eaves flashing along the lower edge of the roof where it meets the fascia. This will prevent water from seeping under the metal roof.
3. Using Roofing Cement
Seal any gaps or exposed nails with roofing cement. This will create a watertight barrier and prevent leaks.
4. Install Valley Flashing
Valley flashing is installed at the intersections of roof slopes. It directs water away from the valley and prevents it from seeping into the roof.
5. Install Pipe Flashings
Install pipe flashings around any pipes that penetrate the roof. These flashings will prevent water from leaking around the pipes.
6. Install Vent Flashings
Vent flashings are installed around roof vents to prevent water from entering the attic.
7. Sealing Around Chimneys
Seal the area around chimneys with high-temperature silicone sealant. This will prevent water from leaking around the chimney and damaging the roof.
8. Inspect and Maintain Regularly
Regularly inspect the roof for any signs of damage or leaks. Clean gutters and downspouts to prevent water buildup. Promptly repair any issues to maintain the roof’s integrity and prevent costly damage.
| Inspection Points | Frequency |
|---|---|
| Check for loose nails or screws | Annually |
| Examine sealant tape for damage | Every 2-3 years |
| Inspect flashing for cracks or tears | Every 5-7 years |
Proper Ventilation for the Metal Roof
Proper ventilation is crucial for a metal roof over shingles to prevent moisture accumulation, corrosion, and premature roof failure. Here are some essential considerations:
1. Intake Vents
Intake vents allow air to enter the attic space at the eaves or soffits. This creates an airflow path and draws outside air into the attic.
2. Exhaust Vents
Exhaust vents expel warm, moist air from the attic through roof vents, such as ridge vents, gable vents, or turbine vents. These vents create a negative pressure that draws air through the intake vents.
3. Roofing Underlayment
Roofing underlayment with moisture-wicking properties helps to prevent moisture from penetrating the attic space and reduces the risk of mold growth.
4. Air Gaps
Maintaining a 1- to 1.5-inch air gap between the metal roofing and the underlayment allows air to circulate and carry away moisture.
5. Ridge Vents
Ridge vents are continuous vents that run along the ridge of the roof and allow air to escape. They are highly effective in releasing hot air and moisture.
6. Gable Vents
Gable vents are installed in the gable ends of the roof and draw air upward from the soffits to the ridge vent.
7. Turbine Vents
Turbine vents are powered by the wind and rotate to expel air from the attic. They are highly efficient but can be noisy.
8. Soffit Vents
Soffit vents are small vents installed in the soffit of the eaves and allow air to enter the attic.
9. Air Intake to Exhaust Ratio
The ratio of intake to exhaust vents should be balanced. For every square foot of intake vent area, there should be two to three square feet of exhaust vent area. This ensures proper airflow and ventilation throughout the attic space.
| Type of Vent | Description |
|---|---|
| Intake Vent | Allows air to enter the attic space |
| Exhaust Vent | Expels warm, moist air from the attic |
| Roofing Underlayment | Protects the attic from moisture |
| Air Gap | Allows air to circulate between the metal roof and underlayment |
Maintenance and Inspection of the Metal Roof
Maintaining and inspecting your metal roof regularly ensures its longevity and performance. Here are crucial steps:
1. Annual Inspection
Schedule an annual inspection to check for signs of damage, corrosion, or loose components. Inspect all areas, including seams, flashings, and fasteners.
2. Check Drainage
Debris can accumulate in gutters and downspouts, obstructing proper drainage. Clean them regularly to prevent water pooling and potential leaks.
3. Remove Debris
Use a soft brush or leaf blower to remove leaves, dirt, and other debris from the roof surface. Accumulation can trap moisture and promote corrosion.
4. Seal Leaks
If you detect any leaks, promptly seal them using appropriate sealant specifically designed for metal roofs.
5. Touch Up Paint
Minor paint damage can lead to corrosion. Touch up any scratches or scuffs with a high-quality metal roof paint matched to the original color.
6. Inspect Flashings
Flashings around chimneys, vents, and valleys are crucial for preventing water infiltration. Check for any loose or damaged flashings and repair them immediately.
7. Check Fasteners
Fasteners gradually loosen over time. Regularly inspect them and tighten any loose screws or nails to prevent leaks or wind damage.
8. Inspect Seams
Seams are vital points of vulnerability. Check for any loose or detached seams and reseal them using an appropriate sealant.
9. Check for Rust
Rust is an early sign of corrosion. Inspect the roof for signs of rust and promptly address any issues to prevent further damage.
10. Pet Precautions
Pets can scratch or puncture metal roofs. Keep them off the roof or use protective measures such as mats or barriers to minimize damage.
How To Put Metal Roof Over Shingles
It is possible to install a metal roof over shingles, but it is important to note that this is not a common practice. Metal roofs are typically installed over plywood or OSB decking, and installing them over shingles can create a number of problems. Nevertheless here are the steps:
- Remove any loose or damaged shingles.
- Install a layer of roofing felt纸毛毡纸 over the shingles.
- Install the metal roofing panels over the roofing felt.
- Secure the metal roofing panels with screws or nails.
- Apply a sealant around the edges of the metal roofing panels.
People Also Ask
Can you put metal roofing over shingles?
Yes, it is possible to install a metal roof over shingles, but it is not a common practice. Metal roofs are typically installed over plywood or OSB decking, and installing them over shingles can create a number of problems.
What are the challenges of installing a metal roof over shingles?
One of the biggest challenges of installing a metal roof over shingles is that the shingles can create an uneven surface, which can make it difficult to install the metal roofing panels properly. Additionally, the shingles can trap moisture, which can lead to corrosion of the metal roofing panels.
What are the benefits of installing a metal roof over shingles?
There are some benefits to installing a metal roof over shingles, such as increased durability, energy efficiency, and fire resistance. However, it is important to weigh these benefits against the challenges before making a decision.
