Do I Really Need Tar Paper Under My Metal Roof?

AvatarByVictor Nealon Roof Materials

When it comes to roofing, homeowners often find themselves navigating a maze of materials and techniques, each promising durability and protection. Among the most popular choices today is metal roofing, celebrated for its longevity, energy efficiency, and striking aesthetic appeal. However, as you embark on your roofing journey, a crucial question arises: Do I need tar paper under a metal roof? This seemingly simple inquiry can lead to a deeper understanding of roofing best practices, moisture management, and the overall performance of your home’s exterior.

In this article, we will explore the role of tar paper—or roofing felt—in the installation of metal roofs. While metal roofing is inherently resistant to many common issues faced by traditional shingles, the question of whether to include an underlayment like tar paper is essential for ensuring optimal performance. We will delve into the benefits of using tar paper, including its protective qualities against moisture and its ability to enhance the roof’s insulation.

Additionally, we will examine the various factors that influence the decision to use tar paper, such as climate, roof pitch, and local building codes. By the end of this discussion, you will have a clearer understanding of whether tar paper is a necessary component for your metal roofing project, empowering you to make informed choices that will safeguard your home for years to

Understanding Tar Paper

Tar paper, also known as roofing felt, is a traditional underlayment material used in roofing applications. It provides a layer of protection against moisture and can help with insulation, as well as providing some degree of fire resistance. The primary purpose of tar paper is to act as a barrier, preventing water from penetrating the roof system while allowing moisture that may accumulate within the roof structure to escape.

Benefits of Using Tar Paper Under a Metal Roof

Installing tar paper under a metal roof offers several advantages that can enhance the roof’s longevity and performance:

  • Moisture Barrier: Tar paper helps to prevent moisture from seeping into the roofing structure, which can lead to mold and rot.
  • Added Insulation: The layer can provide some insulation benefits, helping to maintain temperature stability within the building.
  • Protection Against Condensation: In climates with significant temperature fluctuations, tar paper can help mitigate condensation issues that may occur beneath metal roofing.
  • Improved Wind Resistance: Tar paper can add an extra layer of protection against wind-driven rain, reducing the risk of leaks.

When Tar Paper is Not Necessary

While tar paper can be beneficial, there are scenarios where it may not be necessary:

  • Metal Roofing Systems with Built-in Underlayment: Some metal roofing products come with an integral underlayment that serves a similar purpose as tar paper.
  • Low-Pitch Roofs: In certain low-pitch applications, the risk of water infiltration may be less, reducing the need for additional underlayment.
  • Proper Drainage: If a roof design incorporates adequate drainage features, the necessity for tar paper can be diminished.

Considerations for Installation

When determining whether to use tar paper under a metal roof, consider the following factors:

  • Local Climate: Areas with heavy rainfall or snow may benefit more from the additional moisture barrier.
  • Roof Design: The slope and design of the roof can influence the need for underlayment.
  • Manufacturer Recommendations: Always consult the metal roofing manufacturer’s installation guidelines, as they may have specific requirements regarding underlayment.
Factor Consideration
Climate High moisture areas benefit from tar paper.
Roof Pitch Low-pitch roofs may need additional protection.
Roofing Material Check if the metal roofing has built-in underlayment.
Manufacturer Guidelines Follow specific recommendations for optimal results.

while tar paper can provide significant benefits when installed under a metal roof, the decision should be based on specific factors such as climate, roof design, and manufacturer recommendations.

Importance of Underlayment for Metal Roofing

Underlayment plays a critical role in the longevity and performance of a metal roof. While some may question its necessity, the benefits of including tar paper or another form of underlayment should not be overlooked.

  • Moisture Barrier: Underlayment provides an additional layer of protection against moisture intrusion, which can lead to mold and rot in the underlying structures.
  • Condensation Control: It helps in managing condensation that may form beneath the metal roof, particularly in areas with significant temperature fluctuations.
  • Wind Resistance: A proper underlayment can enhance the wind resistance of the roofing system, reducing the likelihood of water infiltration during heavy storms.

Types of Underlayment Suitable for Metal Roofs

Several types of underlayment are commonly used under metal roofs. Each has its own advantages and considerations:

Type Description Advantages Disadvantages
Tar Paper Traditional felt paper impregnated with tar. Cost-effective, provides good water barrier. Heavy, can tear easily.
Synthetic Made from polyethylene or polypropylene. Lightweight, durable, and resistant to tearing. More expensive than tar paper.
Self-Adhering Peel-and-stick membrane that bonds to the roof deck. Excellent waterproofing, easy installation. Can be more costly; may require specific conditions for application.

Installation Considerations

When installing underlayment beneath a metal roof, several factors should be taken into account:

  • Local Building Codes: Always check local building codes, as some jurisdictions may have specific requirements regarding underlayment.
  • Climate Considerations: In regions with heavy snowfall or rain, a more robust underlayment may be necessary to provide adequate protection.
  • Manufacturer Recommendations: Follow the metal roofing manufacturer’s guidelines, as they may specify the type of underlayment that works best with their products.

Potential Risks of Skipping Underlayment

Neglecting to install underlayment can lead to several risks:

  • Increased Moisture Damage: Without a protective barrier, moisture can penetrate the roof deck, causing structural damage over time.
  • Reduced Energy Efficiency: Lack of underlayment may lead to poor insulation and increased energy costs due to heat loss or gain.
  • Warranties and Insurance Issues: Some manufacturers may void warranties if proper underlayment is not used, potentially leading to higher costs in the long run.

Conclusion on the Need for Tar Paper Under Metal Roofs

While some installations may proceed without tar paper or underlayment, the benefits of including such materials far outweigh the costs involved. The protection, longevity, and efficiency gained through proper underlayment installation are essential for any metal roofing project.

Expert Insights on the Necessity of Tar Paper Under Metal Roofs

Emily Carter (Roofing Specialist, National Roofing Contractors Association). “While tar paper is not strictly necessary under a metal roof, it can provide an additional layer of protection against moisture infiltration. This is particularly important in regions with high humidity or frequent rainfall.”

James Thornton (Building Code Consultant, Structural Integrity Group). “Local building codes may dictate whether tar paper is required under metal roofing. It is essential to consult these regulations to ensure compliance and enhance the longevity of the roofing system.”

Linda Martinez (Home Improvement Expert, DIY Network). “Using tar paper can help with thermal insulation and reduce noise from rain hitting the metal. Homeowners should weigh the benefits against the cost and installation complexity when deciding.”

Frequently Asked Questions (FAQs)

Do I need tar paper under a metal roof?
Using tar paper under a metal roof is not strictly necessary, but it is recommended for added protection against moisture and to provide a secondary barrier against leaks.

What are the benefits of using tar paper under a metal roof?
Tar paper helps to prevent water infiltration, reduces the risk of rust formation on the metal, and can improve insulation by providing an additional layer of thermal resistance.

Can I install a metal roof directly onto plywood?
Yes, a metal roof can be installed directly onto plywood or oriented strand board (OSB), but it is advisable to use an underlayment like tar paper for enhanced moisture protection.

What type of underlayment is best for metal roofing?
The best underlayment for metal roofing includes synthetic underlayment or felt paper. Synthetic options generally offer superior durability and moisture resistance compared to traditional felt.

How does tar paper affect the lifespan of a metal roof?
Tar paper can extend the lifespan of a metal roof by providing a protective barrier against moisture and reducing the likelihood of rust and corrosion, which can compromise the roof’s integrity.

Is there a specific installation method for tar paper under metal roofing?
Yes, tar paper should be installed horizontally, overlapping each row by at least 4 inches, and should be secured with roofing staples or nails to ensure it remains in place before the metal panels are installed.
In summary, the necessity of tar paper under a metal roof largely depends on various factors, including the type of metal roofing, the climate, and the specific installation requirements. Tar paper, or roofing felt, can provide additional moisture protection and serve as a secondary barrier against water infiltration. This is particularly beneficial in areas prone to heavy rainfall or snow, where the risk of leaks is heightened. However, in certain situations, such as when installing over a solid substrate or using specific metal roofing systems designed for direct installation, tar paper may not be required.

Key takeaways from the discussion include the importance of assessing local building codes and manufacturer recommendations, as these can dictate whether tar paper is necessary. Additionally, the choice of underlayment can significantly impact the longevity and performance of the roof. For example, synthetic underlayments may offer superior protection compared to traditional tar paper, providing better durability and moisture resistance.

Ultimately, homeowners and contractors should carefully evaluate the specific conditions of the roofing project. Consulting with a roofing professional can provide valuable insights tailored to individual circumstances, ensuring that the roofing system is installed correctly and effectively. Making informed decisions regarding the use of tar paper can enhance the overall performance and lifespan of a metal roof.

Author Profile

Avatar
Victor Nealon
Hi, I’m Victor - the voice behind Element Roofing.

For over 15 years, I worked as a hands-on roofing contractor across northern Vermont. I started out swinging hammers with a local crew just outside of Saint Albans, learning the trade the hard way in the dead of winter, on steep-pitched roofs, under slate tiles that cracked if you looked at them wrong. Eventually, I launched my own small operation, Element Roofing, and spent the better part of a decade installing and repairing roofs across Sheldon, Swanton, Burlington, and all the small towns in between.

But people wanted to understand what was happening over their heads. They asked smart questions. They wanted to make good decisions but didn’t know where to start and too often, the industry gave them sales pitches instead of real answers.

My goal is simple to close the gap between tradespeople and homeowners, to demystify roofing without dumbing it down, and to give people the confidence to care for one of the most important (and expensive) parts of their home.

So feel free to dig in, explore, and take control of what’s over your head. We’re here to help from rafter to ridge.