Embark on a transformative roofing journey by seamlessly installing a metal roof over your existing shingles. Unlike traditional roof replacements that require extensive removal and disposal, this innovative technique preserves your existing roof while enhancing its durability and aesthetics. With meticulous planning and careful execution, you can elevate your home’s protection and curb appeal without the hassle and expense of a complete tear-off.
Transitioning to a metal roof offers a myriad of benefits that make it an investment worth considering. Enhance your home’s energy efficiency, as metal roofs reflect sunlight, reducing heat absorption and lowering cooling costs. Embrace peace of mind knowing that your roof can withstand extreme weather conditions, such as high winds, hail, and heavy snow loads. Moreover, metal roofs are virtually maintenance-free, eliminating the need for costly repairs or replacements down the road.
Before embarking on this roofing adventure, meticulous preparation is paramount. Ensure that your existing shingles are in good condition, as any underlying damage can compromise the integrity of your new metal roof. Clear away any debris or moss from the surface and inspect for any areas that may require additional repairs. By laying a solid foundation, you can set the stage for a successful and long-lasting metal roof installation.
Assessing Shingle Roof Compatibility
Before installing a metal roof over shingles, it’s crucial to determine if your existing shingle roof is compatible with the metal roofing system you intend to install. Incompatible shingles can compromise the performance and longevity of the metal roof, leading to potential issues down the line.
The following factors should be considered when assessing shingle roof compatibility:
- Condition of Shingles: Shingles should be in good condition, free from severe damage, cupping, buckling, or missing shingles. Loose or compromised shingles may not provide a stable surface for the metal roof, leading to potential issues with attachment and weather resistance.
- Type of Shingles: Certain types of shingles, such as fiber cement or rubber shingles, may not be suitable for installing a metal roof over. These shingles may have different properties and textures that can affect the adhesion and performance of the metal roofing system.
- Slope of Roof: The slope of the roof is also a factor to consider. Metal roofing systems typically require a minimum slope, usually around 1:12. If the roof slope is too shallow, it may not be able to effectively shed water and debris, potentially leading to leaks and other problems.
- Roof Structure: The structural integrity of the roof is crucial to support the additional weight of a metal roof. Ensure that the underlying roof framing is sufficient to handle the metal roofing system’s weight without causing excessive deflection or structural damage.
Inspecting the Roof Deck
Before installing a metal roof over shingles, it’s crucial to carefully inspect the existing roof deck to ensure its integrity and suitability for the new roofing system.
Here’s a step-by-step guide on how to inspect the roof deck:
- Clear the roof: Remove any debris, leaves, or objects from the roof deck. This will allow you to see the surface clearly and identify any potential issues.
- Look for soft or spongy spots: Walk over the roof deck and check for any areas that feel soft or spongy underfoot. This could indicate moisture damage or rot, which needs to be addressed before installing the metal roof.
- Examine the shingles and underlayment: Inspect the condition of the existing shingles and underlayment. Replace any missing, damaged, or curled shingles. Ensure the underlayment is intact and free of tears or punctures.
- Check the roof structure: Inspect the roof joists, rafters, and trusses for any signs of damage or decay. Look for cracks, loose joints, or sagging. If you notice any structural issues, consult a qualified roofing contractor.
- Pay attention to the flashing: Examine the flashing around chimneys, vents, and skylights. Ensure the flashing is in good condition and properly sealed to prevent water leaks.
- Document your findings: Take photos or make notes of any issues you find during the inspection. This will serve as a record of the roof’s condition before installing the metal roof.
Recommended Tools for Roof Deck Inspection:
| Tool | Purpose |
|---|---|
| Roofing ladder | Safe and stable access to the roof |
| Pry bar or flat shovel | Probing for soft spots |
| Flashlight | Illuminating dark or obstructed areas |
| Camera or notepad | Documenting inspection findings |
Installing Underlayment
The underlayment is a critical component of any roofing system because it provides additional protection against moisture, wind, and ice. When installing a metal roof over shingles, you must remove the existing shingles before installing the underlayment.
There are many different types of underlayment available, so choosing one that is appropriate for your climate and roofing system is essential. In general, thicker underlayment provides more protection but is also more expensive. A “breathable” underlayment allows moisture to escape while preventing water from penetrating the roof deck.
Step 1: Remove the Old Shingles
Use a pry bar to carefully remove the old shingles. Work in small sections, starting at the top of the roof and working your way down. Be careful not to damage the roof deck.
Step 2: Inspect the Roof Deck
Once the old shingles have been removed, inspect the roof deck for any damage. Repair any damaged areas before installing the underlayment.
Step 3: Install the Underlayment
Roll out the underlayment over the roof deck, starting at the bottom and working your way up. Overlap the underlayment by at least 6 inches, and secure it with roofing nails.
Additional Tips for Installing Underlayment over Shingles
| Tip |
|---|
| To ensure a proper seal, overlap the underlayment along the edges of the roof deck. |
| Use a roofing nailer to secure the underlayment to the roof deck. |
| Avoid walking directly on the underlayment, as this could damage it. |
| If you are installing a metal roof over a steep-sloped roof, consider using a self-adhering underlayment for added protection against wind. |
Installing Drip Edge
Drip edge is metal flashing that is installed along the eaves and rakes of the roof to prevent water from seeping under the shingles and causing damage to the roof deck. It is typically made of aluminum or galvanized steel and is available in a variety of colors to match the roof shingles.
To install drip edge, follow these steps:
- Measure and cut the drip edge to the desired length.
- Place the drip edge along the eaves or rakes of the roof, making sure that it is flush with the edge of the roof deck.
- Secure the drip edge to the roof deck using roofing nails or screws spaced 6 to 8 inches apart.
- Overlap the drip edge pieces by at least 2 inches and seal the seams with roofing cement.
- Bend the drip edge up at a 90-degree angle at the corners of the roof to create a drip path for water. Use roofing cement to seal the corners and prevent water from leaking through.
| Material | Gauge | Width | Length |
|---|---|---|---|
| Aluminum | 0.032″ | 10″ | 10′ |
| Galvanized steel | 0.024″ | 12″ | 12′ |
Positioning Metal Roof Panels
Once you have installed the underlayment, you can start positioning the metal roof panels.
1. Start at the Bottom
Begin installing the panels at the bottom edge of the roof and work your way up.
2. Overlap the Panels
Each panel should overlap the previous panel by at least 1-1/2 inches.
3. Use Screws to Secure
Use roofing screws to secure the panels to the roof deck. Drive the screws through the top of the panel and into the deck.
4. Line Up the Panels
Make sure the panels are lined up straight and evenly before securing them.
5. Cut the Panels
If necessary, cut the panels to fit around obstacles such as chimneys or skylights.
6. Seal the Overlaps
To prevent water from seeping into the roof, apply a sealant to the overlaps between the panels.
| Type of Sealant | Application |
|---|---|
| Butyl tape | Applied to the underside of the overlap before installing the panels |
| Butyl caulk | Applied to the joint between the panels after installation |
| Silicone caulk | Used for areas that require a more flexible seal |
Securing Metal Panels
Once the underlayment is installed, you can begin securing the metal panels. Use 1-inch roofing screws to fasten the panels to the roof deck through the underlayment. Drive the screws into the high ribs of the panels to ensure a tight fit. Start at the eaves and work your way up the roof, overlapping the panels by at least 2 inches.
Use a chalk line to mark the location of the screws, ensuring that they are evenly spaced. Countersink the screws slightly below the surface of the panels to prevent damage to the paint finish.
At the gable ends, you will need to trim the panels to fit. Use a metal shear or circular saw with a metal cutting blade to cut the panels to the desired length. Be sure to wear safety glasses and gloves when cutting metal.
Once the panels are cut to size, secure them to the roof deck with 1-inch roofing screws. Overlap the panels by at least 2 inches and countersink the screws slightly below the surface of the panels.
At the ridge of the roof, you will need to install a ridge cap. A ridge cap is a metal piece that covers the joint between the two roof panels. Secure the ridge cap to the roof deck with 1-inch roofing screws.
Once the metal panels are secured, you can install the flashing. Flashing is a metal material installed around chimneys, vents, and other roof penetrations to prevent water leaks. Cut the flashing to fit around the penetration and secure it with roofing cement and 1-inch roofing screws.
Trimming and Adjusting
It’s important to cut the shingles so that the new metal panels can fit correctly and overhang the old shingles by 12 inches. To do this, use a chalk line to snap a straight line 12 inches from the bottom of the old shingles.
Next, use a utility knife (or roofing snips and shears) to trim the shingles along the chalk line. Keep the cut as straight and even as possible. If you need to make a curve cut, you can use a jigsaw or scroll saw.
Once the shingles are all trimmed, you can start installing the metal roof panels. Depending on the type of metal panel you are using, you may need to adjust them slightly to fit tightly together.
To adjust the panels, use a pair of pliers or tin snips to gently bend or crimp the edges. Be careful not to bend the panels too much, as this can damage them. Once the panels are adjusted, secure them in place with screws or nails.
Adjusting Panel Overhang
The overhang of the metal panels is important to ensure proper drainage and prevent water from leaking behind the roof. The overhang should be at least 12 inches, and it can be adjusted by trimming the panels.
To trim the panels, use a chalk line to snap a straight line 12 inches from the edge of the roof. Then, use a utility knife or roofing snips to cut the panels along the chalk line.
| Panel Type | Adjustment Method |
|---|---|
| Standing Seam | Crimp the seam to adjust the width |
| Corrugated | Overlap the panels and adjust the overlap width |
| Interlocking | Slide the panels together and adjust the interlocking position |
Sealing Laps and Seams
To ensure a waterproof seal, all laps and seams in the metal roofing system must be properly sealed. This involves using a high-quality sealant or mastic that is compatible with the metal and the underlayment.
Lap Sealants
Lap sealants are used to seal the overlaps between the metal roofing panels. These sealants are typically applied using a caulking gun.
Seam Sealants
Seam sealants are used to seal the seams where two or more panels are joined together. These sealants are typically applied using a brush or a roller.
Butyl Tape
Butyl tape is a self-adhesive tape that can be used to seal laps and seams. This type of tape is typically applied by hand.
Caulking
Caulking is a common sealant that can be used to seal laps and seams. However, it is important to use a caulking that is compatible with the metal and the underlayment.
Sealant Application
When applying sealants or mastic, it is important to follow the manufacturer’s instructions. This will ensure that the sealant is properly applied and will provide the desired level of protection.
Sealant Inspection
It is important to inspect the sealant regularly to ensure that it is still in good condition. If the sealant is cracked or damaged, it should be repaired or replaced.
Sealant Table
The following table provides a summary of the different types of sealants that can be used for metal roofing:
| Type of Sealant | Application |
|---|---|
| Lap Sealant | Overlaps between roofing panels |
| Seam Sealant | Seams where panels are joined |
| Butyl Tape | Self-adhesive tape for laps and seams |
| Caulking | Compatible with metal and underlayment |
How To Install A Metal Roof Over Shingles
Installing a metal roof over shingles can be a great way to add durability and value to your home. However, it’s important to note that this is a more complex process than installing a metal roof over plywood. Here are the steps on how to install a metal roof over shingles:
1. **Prepare the shingles.** Before you begin installing the metal roof, you need to prepare the shingles by removing any loose or damaged shingles. You should also check for any areas where the shingles are not properly sealed and apply sealant as needed.
2. **Install the underlayment.** The underlayment is a layer of material that is installed between the shingles and the metal roof. It helps to protect the shingles from moisture and wind damage. There are several different types of underlayment available, so be sure to choose one that is appropriate for your climate and the type of metal roof you are installing.
3. **Install the metal roof panels.** The metal roof panels are installed over the underlayment. They are typically attached to the roof deck with screws or nails. Be sure to follow the manufacturer’s instructions for installing the panels.
4. **Trim the metal roof panels.** Once the metal roof panels are installed, you need to trim them around the edges of the roof. This can be done with a saw or a metal shears.
5. **Seal the metal roof panels.** The final step is to seal the metal roof panels. This will help to prevent water from leaking into the roof. There are several different types of sealants available, so be sure to choose one that is appropriate for the type of metal roof you are installing.
People Also Ask About Installing Metal Roofing Over Shingles
What are the benefits of installing a metal roof over shingles?
There are several benefits to installing a metal roof over shingles including:
- Increased durability: Metal roofs are much more durable than shingle roofs and can last for 50 years or more.
- Lower energy costs: Metal roofs can reflect heat away from your home, which can help to reduce your energy costs.
- Increased fire resistance: Metal roofs are fire resistant and can help to protect your home from fire damage.
- Improved curb appeal: Metal roofs can give your home a more modern and stylish look.
### Is it difficult to install a metal roof over shingles?
Installing a metal roof over shingles is more complex than installing a metal roof over plywood, but it is still a doable project for DIYers with some experience. Be sure to follow the manufacturer’s instructions carefully and take all necessary safety precautions.
How much does it cost to install a metal roof over shingles?
The cost to install a metal roof over shingles will vary depending on the size of your roof, the type of metal roof you choose, and the complexity of the installation. However, you can expect to pay between $5 and $10 per square foot for a metal roof.
