Lakeland Roofer Installing a Metal Roof Over Shingles
Lakeland Roofer Installing a Metal Roof Over Shingles

Installing a Metal Roof Over Shingles: Ultimate Guide

The allure of a metal roof is undeniable. Known for its longevity, durability, and sleek aesthetics, metal roofing offers a compelling upgrade for homeowners looking to enhance their property’s value and protection. However, the prospect of tearing off existing shingles can be daunting, both in terms of cost and labor. This is where installing a metal roof over shingles comes in as a potential solution.

But is installing a metal roof directly on shingles a viable option? The answer, like most things in construction, is “it depends.” This guide will delve into the intricacies of this installation method, exploring its advantages, disadvantages, key considerations, and the step-by-step process.

Why Choose a Metal Roof?

High angle beautiful wooden house with metal roof

Before diving into the specifics of installing a metal roof over shingle roofing, it’s important to understand why metal roofing is an attractive option in the first place. Here are some of its notable advantages:

Durability

Metal roofs have a significantly longer lifespan compared to traditional asphalt shingle roofs. While asphalt roofs may need to be replaced every 20-30 years, metal roofs can last 50 years or more.

Weather Resistance

Metal roofing is highly resistant to extreme weather conditions, including heavy rain, hail, wind, and fire. This makes it an ideal choice for homeowners living in areas prone to these types of weather events.

Energy Efficiency

Metal roofs reflect sunlight rather than absorb it like asphalt shingles do, which can help reduce cooling costs in the summer.

Environmentally Friendly

Most metal roofs are made from a high percentage of recycled materials, making them a more sustainable option for homeowners.

Numerous Options

Homeowners are not limited in choice when it comes to metal roofing. The market offers a wide variety of colors, finishes, and styles that can suit any home’s aesthetic. Whether you prefer the look of traditional shingles, tiles, or even a sleek, contemporary panel design, there is likely a metal roofing option that will match your home’s appearance. Additionally, metal roofs can be crafted from several types of metals, including aluminum, steel, copper, and zinc.

Pros and Cons of Installing Metal Over Shingles

Pros and Cons of Installing Metal Over Shingles

Before making any decisions, homeowners should understand the advantages and disadvantages of reroofing using metal over shingles.

Advantages

  • Cost-Effectiveness: Removing old shingles adds a significant chunk to the overall project cost of a new roof installation.  This includes not only the cost of labor for removing the shingles, but also the cost of disposal of the old material. Installing metal directly over existing shingles can potentially save a substantial amount of money.
  • Reduced Time: Tearing off shingles is a time-consuming process. This method offers a faster installation, minimizing disruption to your daily life.
  • Environmentally Friendly: Avoiding shingle removal reduces landfill waste, making this a more eco-friendly approach.

Disadvantages

  • Building Codes: Not all localities permit installing metal roofs directly on shingles. Consult your local building department to confirm regulations in your area.
  • Uneven Surface: Shingles create an uneven surface, which can lead to oil canning (wavy appearance) in the metal panels and potential issues with fastener tightness over time.
  • Hidden Damage: Existing problems like leaks or rot may go unnoticed and worsen under the metal roof. This can leave the structure of the roof or the roof decking in bad shape that can ultimate lead to serious issues.
  • Ventilation Concerns: Trapped moisture between the layers can lead to mold and wood rot. Proper ventilation is crucial with this method.

Key Considerations Before You Begin

Be sure to consider the following factors before you begin the process of installing a metal roof over shingles:

Shingle Condition

Your existing shingles should be in good condition, free of significant wear, tear, or leaks. Curled, cracked, or missing shingles are red flags and necessitate shingle removal before metal installation.

Roof Slope

Metal roofs perform best on pitched roofs with a slope exceeding 3:12. Flatter roofs may require additional considerations for drainage.

Metal Roof Type

Certain metal roof styles, like standing seam panels, are better suited for installation over shingles due to their ability to accommodate an uneven surface.

Ventilation

roof ventilation in Lakeland

Proper ventilation is paramount to prevent moisture buildup. Installing a vented underlayment or creating air gaps between the shingles and metal panels is crucial.

Warranty

Ensure the metal roof manufacturer’s warranty explicitly covers installation over existing shingles.

Roof Maintenance

Although metal roofs are relatively low maintenance, regular inspections are crucial to ensure its longevity.

Installing a Metal Roof Over Shingles

Because there are a number of factors to consider and steps involved, it’s generally best to leave the work of installing a metal roof over shingles to a professional roofing company. Here are the steps they will take:

  1. Inspection: A thorough inspection of the roof deck and shingles is essential. The contractor will assess the condition of the shingles, identify any underlying issues, and ensure the structural integrity of the roof can support the additional weight of the metal.
  2. Permitting:  The contractor will secure any necessary permits from your local building department.
  3. Shingle Preparation: In some cases, minor shingle repairs or partial tear-off of damaged areas might be necessary.
  4. Underlayment Installation:  A high-quality, breathable underlayment is installed directly over the existing shingles. This layer provides secondary waterproofing and improves ventilation.
  5. Creating Air Gaps (Optional):  Depending on the chosen metal roofing system and local building codes, battens or furring strips might be installed on top of the underlayment to create an air gap between the shingles and the metal panels. This further enhances ventilation and helps prevent moisture build-up.
  6. Metal Panel Installation:  The chosen metal roofing panels are then secured to the roof deck through the shingles and underlayment using specialized fasteners.  The contractor will ensure proper panel overlap and watertight seams.
  7. Trim Installation:  Drip edges, flashing, and other trim pieces are installed to ensure proper drainage and a finished look.
  8. Final Inspection:  A final inspection is conducted to ensure proper installation, ventilation, and watertightness of the entire roof system.

The Best Roofers in Lakeland and Sarasota

Whether you need a metal roof over or any other roofing services, the team of experienced Lakeland roofers at Stronghold Roofing & Solar is ready to help. Contact us today for a free roof estimate!

FAQ’s – Installing a Metal Roof Over Shingles

Is it always a good idea to install a metal roof over shingles?

It’s recommended that you consult with a professional roofing company to assess your individual situation and determine if this method is the best option for you. Factors such as the condition of your existing shingles, roof slope, and ventilation should all be considered.

Is installing a metal roof over shingles more cost-effective?

In some cases, it can be more cost-effective because it eliminates the need for shingle removal and disposal. However, it’s important to consider the potential hidden damage and any additional ventilation requirements which may impact overall cost.

Can all types of metal roofs be installed over shingles?

Not all metal roof styles are suitable for installation over shingles. Standing seam panels have been proven to be more adaptable to an uneven surface, making them a better choice for this method.

Is there a risk of trapped moisture causing damage?

Yes, if proper ventilation is not established between the shingles and metal panels, trapped moisture can lead to mold, wood rot, and other issues. It’s important to consider ventilation options when installing a metal roof over shingles. 

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