The foundation of a durable and efficient metal roofing system lies not just in the visible panels but in the often-overlooked underlayment. This critical component acts as a protective barrier, safeguarding the roof deck from moisture and providing an additional layer of insulation. With the advancement in roofing technologies, selecting the right underlayment has become pivotal for homeowners aiming to enhance the longevity and performance of their metal roofs. In this article, we delve into the essential aspects of underlayment for metal roofing, highlighting the top choices to consider for your next roofing project.

Understanding Roof Underlayment

Roof underlayment is a layer installed between the roof deck and the metal panels. It serves multiple purposes, including moisture protection, additional insulation, and acting as a secondary barrier against weather elements. The right underlayment choice can significantly impact the overall durability and efficiency of the roofing system.

The Importance of Selecting the Right Underlayment

Choosing the appropriate underlayment for a metal roof is crucial for several reasons:

Moisture Protection: It prevents water that may penetrate the metal panels from reaching the roof deck, thereby reducing the risk of rot and mold development.

Thermal Performance: Certain underlayments offer reflective properties or additional insulation, contributing to the energy efficiency of the home.

Longevity: A high-quality underlayment can extend the life of the entire roofing system by providing an extra layer of protection against physical damage and weather-induced wear and tear.

Top Underlayment Options for Metal Roofs

When it comes to metal roofing, not all underlayments are created equal. Here are the top selections that have proven to offer superior protection and durability:

Synthetic Underlayment

Synthetic underlayments, made from polypropylene, polyethylene, or a combination of both, are a modern solution offering exceptional strength, durability, and moisture resistance. Their lightweight nature makes them easy to install, while their resistance to UV exposure and tear makes them an excellent choice for metal roofing systems.


Durability: Highly resistant to tears and punctures.

Moisture Resistance: Offers superior protection against water infiltration.

Longevity: Designed to last as long as the metal roofing panels.


Cost: Generally more expensive than traditional felt underlayment but justified by the enhanced protection and lifespan.

Felt Underlayment

Felt underlayment, also known as tar paper, is a traditional option made from either organic or fiberglass substrate saturated with asphalt. It comes in two thicknesses: #15 and #30, with the latter providing greater durability.


Cost-Effective: Offers a more affordable option for those on a tight budget.

Ease of Installation: Well-known and widely used, making it familiar to most roofing professionals.


Weight: Heavier than synthetic options, which can complicate the installation process.

Moisture Sensitivity: More susceptible to water damage and deterioration over time.

Self-Adhering Underlayment

Self-adhering, or peel-and-stick, underlayments provide a robust waterproofing solution for metal roofs. Made from rubberized asphalt, these underlayments adhere directly to the roof deck, creating a seamless barrier against moisture.


Waterproofing: Offers excellent resistance to water and ice damming.

Ease of Installation: The self-adhesive backing simplifies the installation process.

Durability: Provides a durable, puncture-resistant layer under metal panels.


Temperature Sensitivity: May become less adhesive in cold weather, requiring careful handling and installation.

Making the Right Choice

Selecting the best underlayment for your metal roof involves considering several factors, including climate, roof design, and budget. It’s essential to consult with experienced roofing professionals who can provide tailored advice based on your specific needs and local weather conditions. For homeowners in McMurray, PA, and the surrounding areas, Planet Roof stands ready to offer expert guidance and installation services, ensuring your metal roof is equipped with the optimal underlayment for long-lasting protection and performance.


The underlayment is a critical component of any metal roofing system, offering essential protection against moisture, enhancing thermal performance, and extending the lifespan of the roof. By choosing the right underlayment—whether synthetic, felt, or self-adhering—homeowners can significantly improve the durability and efficiency of their metal roofs. With the expertise of seasoned professionals like Planet Roof, selecting and installing the ideal underlayment becomes a seamless process, ensuring your roof remains strong and resilient for years to come.