Underlayment for Roofing: Types and Uses

Jan 8, 2024

When it comes to the world of roofing, it’s the unsung heroes that often make the difference. And for us, one of those quiet achievers is undoubtedly the roofing underlayment. Used as a powerful protective barrier, the underlayment goes between the roof deck and the outer roofing materials, standing guard against weather elements. So, it’s clear that understanding about roof underlayment types is essential for any homeowner.

There are three primary types of underlayment for roofs; each serves a unique purpose and brings its own benefits to the table. These include asphalt-saturated felt, rubberized asphalt, and non-bitumen synthetic. Weather proofing your home begins with the correct choice of roof underlayment options. Let’s take a closer look into these versatile roof underlayment materials.

Remember, underlayment is an integral part of modern roofs—perhaps its least appreciated part—that plays a crucial role in managing water intrusion, alongside contributing to the overall performance of the roofing system. The key to a happy home is a well-guarded roof, and the secret to that lies in the right choice of waterproof underlayment for roofing.

Key Takeaways

  • Understanding the types of underlayment for roofs is key for effective home maintenance.
  • Roof underlayment forms a protective barrier between the roof deck and the outer roofing material.
  • Three main types of underlayment exist: asphalt-saturated felt, rubberized asphalt, and synthetic underlayment.
  • The right choice of roof underlayment can significantly improve a home’s protection against adverse weather conditions.
  • Correctly installed underlayment ensures prolonged roof lifespan and overall performance.

An Overview of Roof Underlayment Materials

When it comes to enhancing roof performance, the importance of selecting the right underlayment cannot be overstated. This unseen yet critical component serves as a protective barrier, offering additional insulation and acting as a waterproof shield for your roof. In our quest to find the best roofing underlayment, let us explore various options that cater to a variety of roofs and conditions.

Importance of Selecting the Right Underlayment

In the often complex world of roofing, not every underlayment is created equal. The diverse aspects of roof anatomy, regional weather conditions, and your roof’s exposure to the elements play a crucial role in choosing the roofing underlayment that gives your roof the protection it deserves. The correctly chosen underlayment can significantly enhance your roof’s ability to withstand environmental factors such as heat, damaging UV exposure, and moisture.

Aspects of Underlayment Performance

One key aspect of underlayment performance is its strength. A sturdy underlayment can effectively resist the wear and tear of extreme weather conditions and protect your roof from potential damage. The elasticity of the underlayment also matters as it allows it to flex and move with the roof deck, thereby reducing the chances of tears that could lead to leaks.

Resistance to UV damage is another vital performance aspect. A UV-resistant underlayment will prevent sunlight from degrading the material, ensuring it remains effective for a longer span. Lastly, the ability to provide an impermeable layer between the roof deck and the outer roofing materials is crucial to protect the deck from water absorption and fungal growth.

Performance AspectBenefits
StrengthResists wear and tear, protects from potential damage
ElasticityFlexes and moves with the roof deck, reducing chances of tears and leaks
UV ResistancePrevents sunlight from degrading the underlayment
Water and Fungi ResistanceProvides an impermeable layer that protects the roof deck from water absorption and fungal growth

In the end, whether you’re a homeowner or a professional roofer, remember, there’s more to a roof than just the shingles you see. To extend your roof’s life and optimize its performance, a deep understanding of roofing underlayment types and the factors driving their performance is essential.

Rolled Out: Asphalt-Saturated Felt Underlayment

As the cornerstone of traditional roofing safety, asphalt-saturated felt underlayment has stood the test of time. Made from organic materials such as recycled paper and rags or fiberglass mat, our understanding and application of this underlayment has come a long way.

Traditional Organic vs. Fiberglass Options

The two main types of asphalt-saturated felt are traditional organic underlayment and fiberglass-based underlayment. Traditional organic felts have a base of cellulose fibers, while fiberglass felts use a mat of glass fibers as its base – each offering their own unique benefits and drawbacks.

Weight Differences: 15-Pound vs. 30-Pound Felt

Asphalt-saturated felt underlayment generally comes in two different weights, denoted as 15-pound or 30-pound. Still, you might ask, what does this mean for your roofing project? Simply put, the heavier 30-pound underlayment provides a thicker layer and thus better durability and protection against water penetration. In contrast, 15-pound underlayment is lighter and more budget-friendly, while still offering adequate water resistance for most residential roofs.

 15-Pound Felt30-Pound Felt
ThicknessLess ThickMore Thick
Water ResistanceAdequateExcellent

Water Resistance Capabilities and Limitations

Asphalt-saturated underlayment serves as a waterproof underlayment for roofing, offering a good degree of resistance against water. However, it’s worth noting that it is not wholly waterproof and might absorb more water when exposed to moisture for an extended period. Therefore, for roofs in areas of heavy rainfall or humidity, it would be better to consider a fully waterproof underlayment for roofing.

Ultimately, it is important to understand that while asphalt-saturated felt underlayment offers budget-friendly and adequate protection for most roofs, there might be other options to consider. The best roofing underlayment for your project will depend on factors like your climate, the slope of your roof, and your budget. Therefore, it is recommended to consult with a roofing professional who can advise you on the best choice for your specific situation.

Making the Superior Choice: Synthetic Roofing Underlayment

In your path to a seamless roofing experience, considering a synthetic roofing underlayment could prove to be highly beneficial. Made from exceptional polymers like polypropylene or polyethylene, synthetic roofing underlayments particularly stand out among traditional underlayment choices.

Noteworthy for their lightweight nature, impressive strength, and resistance to fungal growth, they are becoming increasingly favoured in the home improvement sector. The provision of excellent waterproof underlayment for roofing is one of the major advantages of these synthetic alternatives. More so, they have proven to withstand prolonged UV exposure without degenerating over time, which is a remarkable property to consider.

One of the remarkable features of these underlayments is their breathable nature. A breathable roofing underlayment like this allows your home to retain its protective coat by maintaining its resistance to water and avoiding unsightly wrinkles due to their moisture-resistant characteristics.

In turn, this helps preserve the overall aesthetics of the building while also adding an additional layer of protection to the roof installation. By making such a superior choice for underlayment, home owners can rest assured of extended protection and longevity of their roof.

While the choice can be influenced by various factors such as budget, type of roofing material and environmental conditions, leaning towards synthetic underlayment would be a commendable plan to enhance the durability and effectiveness of your roof.

Road to Durability: Rubberized Asphalt Underlayment

Nurturing a roof means safeguarding everything beneath it. Always seeking to use the best roofing underlayment, we place great value in the benefits of rubberized asphalt underlayment. Known for its resilience and versatility, this underlayment offers an amalgamation of beneficial traits that put it ahead in the race for supremacy among roofing materials. With self-adhering properties and a dense likeability for polymers, rubberized asphalt underlayment contests as a formidable option.

Self-Adhering Properties for a Secure Bond

What stands out about rubberized asphalt underlayment is its self-adhering nature. This is something that’s not just a marketing ploy, but a proven trait that roofers can attest to. It clings to roof decking, creating a cozy, weather-tight bond that blocks out water in all forms. These self-adhering properties provide excellent waterproofing advantages that will protect your roof from adverse weather conditions.

The Perks of Polymer-Modified Bitumen

The excellence of rubberized asphalt underlayment is further boosted by its polymer-modified bitumen content. This alone adds a new layer of advantages, increasing resistance to heat and improving elasticity. More so, these underlayments can resist temperatures up to 250° F without showing signs of degradation. This makes rubberized asphalt underlayment the ideal choice for high-heat environments and various roofing materials like metal roofs.

Our Favourite Brands

RuberoidPremium performance modified bitumen membrane
GraceHighly durable, elegant finish
GAF Tri-PlyTop-of-the-line thermal stability and elongation capabilities

Each brand has its unique selling points, depending on the specific needs of your project. They all showcase the inherent durability of rubberized asphalt underlayment and the benefits of polymer-modified bitumen. While being easy to install, they offer outstanding protection from water penetration, making them hard contenders in providing the best roofing underlayment.

Roofing Underlayment Types: From Classic to Innovative Solutions

Roofing technology has come a long way, creating an impressive range of roof underlayment options. Initially, the traditional asphalt-saturated felt dominated the space. However, the evolution in the industry has introduced innovative solutions that offer high-temperature resistance, resilience in extreme weather conditions, and enhanced waterproofing capabilities.

These cutting-edge roofing underlayment materials include the likes of rubberized asphalt and non-bitumen synthetics. These advanced options are designed to cater to specific demands, allowing homeowners and roofing professionals can pick and choose according to their unique requirements and climatic conditions.

“Every homeowner’s roofing scenario is different. Therefore, the breadth and diversity in underlayment types enable us to serve the individual needs of consumers, matching the underlayment to their specific roofing scenarios and environmental challenges.”

As the industry continues to evolve, we can only expect to see more advanced, efficient, and climate-adaptive types of underlayment for roofs. In the meantime, whether you’re building a new roof or replacing an old one, it’s vital to select a solution that offers durability, weather-resistance, and excellent performance for the years to come.

Installation Pointers for Adequate Roof Protection

When it comes to having a roof that delivers adequate protection, the right choice boils down to not just selecting the best roofing underlayment, but also ensuring its proper installation. Whether it’s an asphalt-saturated felt or a synthetic underlayment, installation plays a pivotal role in optimizing the protective features of these materials. In this section, we’ll delve into practical tips for the installation of felt underlayment and its synthetic counterparts.

Installation of Felt Underlayment

Overlapping and Slope Considerations

To maximize your roof’s protection against water infiltration, overlaps on the underlayment should not be taken lightly. For roofs with a low slope, the underlayment should overlap by at least 19 inches, while steeper slopes require a minimum overlap of 2 inches. Beyond deploying overlap as a mechanism for preventing water invasion, it’s also vital to consider the roof’s slope. Underlayment installations vary based on whether the roof slope is steep or low, with each type of slope demanding unique procedures.

Fastening Techniques: From Staples to Plastic Caps

Fastening is another crucial aspect of choosing roofing underlayment and ensuring it delivers optimum performance. While staples are standard equipment for fastening underlayment, areas with high wind necessitate additional fastening measures. Depending on the wind intensity, homeowners may need to resort to plastic windstrips or cap fasteners. Keep in mind that improper fastening can trigger underlayment failure just as much as improper overlaps can, putting your roof’s protection in jeopardy.

Challenges and Solutions with Different Underlayment Types

As we seek the best underlayment for our project, it is vital to be aware of the challenges you may encounter with different underlayment types and how to overcome them.

Potential Felt Underlayment Issues

When using asphalt roofing underlayment, certain issues may emerge over time. For instance, felt underlayment may absorb water, leading to wrinkling and premature deterioration especially when exposed to harsh conditions. Moreover, the loss of volatiles over time can increase its fragility and rate of moisture absorption.

Understanding the Limitations of Synthetic Underlayment

On the other hand, synthetic roofing underlayment which is popular due to its numerous benefits, also has its own set of challenges. For example, some varieties may not adhere to ASTM standards or might raise potential warranty concerns from particular roofing material manufacturers.

Undoubtedly, knowledge of these potential issues is critical when you are selecting the ideal waterproof underlayment for roofing. Ensuring that the product chosen is suited to the specific needs of your roofing project will play a significant role in the longevity and overall success of the roof’s performance.

Let’s take a closer look at the challenges with both asphalt and synthetic underlayments and ways to mitigate them:

Underlayment TypePotential IssueSuggestion to Overcome
Asphalt Roofing UnderlaymentWater absorption, wrinkling, premature deteriorationEnsure proper installation and selection of high-quality, ASTM-compliant product.
Synthetic Roofing UnderlaymentNon-adherence to ASTM standards, warranty issuesVerify product standards and clarify warranty terms with manufacturer prior to purchase.

With the right attention to detail and ample preparation, you can overcome these hitches, select an appropriate underlayment type, and ensure a durable, weather-resistant roof for your dwelling.

Climate and Underlayment: Making Informed Choices

Regardless of the roofing project you’re undertaking, one fact remains clear: climate considerations are of utmost importance. Such factors play a central role when you’re tasked with choosing roofing underlayment. Remember, your selection must withstand the test of time, argue with mother nature, and still come off unscathed. So, dear reader, let’s explore how climate can influence your decision in detail.

Matching Underlayment to Roof Type and Environmental Conditions

When talking about the best roofing underlayment, there isn’t a one-size-fits-all solution. The right underlayment for a coastal area prone to high winds and torrential rains will differ from that required for a sunny, dry region. Thus, it’s crucial to push the envelope when understanding your local climate conditions, alongside your roof type, before making an informed choice.

The strength and durability of your roof underlayment will depend significantly on your ability to pick a type that matches your environmental conditions meticulously.

For instance, rubberized asphalt underlayments with their self-healing qualities, are ideal for regions prone to leaks, offering superior waterproofing benefits. Conversely, synthetic underlayments, celebrated for their durability and mold resistance, are a safe bet for areas that demand robust shielding against the elements.

Impact of Temperature Extremes on Underlayment Choices

Stepping away from general environmental conditions, it’s important to take stock of how temperature extremes can influence your choice of underlayment. Areas that have to contend with extreme temperature fluctuations may need a tougher type of underlayment, like the rubberized asphalt, able to extend its benefit through harsh conditions. Conversely, regions that enjoy a consistent climate can safely opt for synthetic or even time-tested asphalt-saturated felt underlayments.

  1. Rubberized asphalt: Its ability to withstand and adapt to temperature variations makes it a prime choice for climates that swing between extremes.
  2. Synthetic underlayment: Made typically from polypropylene or polyethylene, these can endure prolonged exposure to the sun without degradation, making them perfect for sunny, dryer areas.
  3. Asphalt-saturated felt: This proves to be a reliable and economical choice for areas with milder, consistent climate conditions.

All said and done, the ultimate goal when choosing an underlayment should be to ensure optimum protection for your roof and guarantee its longevity. And remember, climate plays a critical, non-negotiable role in this critical decision.


As we bring our discussion on roofing underlayment to a conclusion, it is key to remember a few vital points. The purpose of roof underlayment materials cannot be overstated, acting as a protective shield for our homes against the elements. That is why choosing roofing underlayment that corresponds to the specific needs and weather conditions of your location is absolutely essential.

Final Thoughts on Roof Underlayment Selection

Whether your preference leans towards the traditional feel of asphalt-saturated felt, the tough resilience of synthetic, or the superior waterproofing capabilities of rubberized asphalt, the crux of the matter lies in your specific needs. The right choice depends upon the roofing project specifics, environmental conditions, and the kind of protection you want to offer to your home. The variety of roof underlayment materials now available in the market are designed to cater to this wide range of needs so that every homeowner can find the perfect fit for their requirements.

Enhancing Your Roof’s Longevity and Performance

Our homes are our fortresses, safe havens from the world around us. Therefore, every step to preserve the structure and enhance its longevity counts. By investing in the right underlayment, you’re ensuring a longer lifespan for your roof and increases its capacity to withstand harsh weather conditions. By making informed decisions, we empower our roofs to resist the elements effectively and protect the interior, thereby enhancing the durability and performance of our homes. As a result, the importance of opting for the right waterproof underlayment for roofing can never be overstated.

Looking for expert roofing services in DeBary, FL? Reach out to Pinnacle Roofing today and see how we can transform your property with our professional solutions.


What are the main types of roofing underlayment?

The three primary roofing underlayment types are asphalt-saturated felt, rubberized asphalt, and non-bitumen synthetic. Each has unique properties and uses. Choosing the correct underlayment is essential for the longevity and effectiveness of a roof against weather elements.

Why is the selection of the right underlayment so vital?

Selecting the right underlayment is vital as it acts as an insulating barrier and a waterproof layer for the roof. The best roofing underlayment, correctly chosen, can enhance a roof’s ability to withstand environmental factors such as heat, UV exposure, and moisture.

What should I know about asphalt-saturated felt underlayment?

Asphalt-saturated felt underlayment is available in organic and fiberglass options, providing varying degrees of water resistance. However, it can absorb more water and potentially fail sooner if not up to standards or correctly installed.

How does synthetic roofing underlayment compare?

Synthetic roofing underlayment, typically made from polymers like polypropylene or polyethylene, is lightweight, high strength, and fungus resistant. It provides excellent water resistance and can withstand extended UV exposure without degradation.

Why might I choose rubberized asphalt underlayment?

Rubberized asphalt underlayment is known for its self-adhering properties and superior waterproofing benefits due to the seal it creates around fasteners. Its enhanced traits of heat resistance and elasticity make it a suitable choice for harsh environments and various roofing materials including metal roofs.

What factors should I consider during the installation of roofing underlayment?

Proper installation is key. Overlaps should be a minimum of 19 inches on low-slope roofs and at least 2 inches on steep-slope roofs. Staples are commonly used for fastening. However, in high-wind areas, additional measures such as plastic windstrips or caps are recommended.

Are there issues to be aware of with different underlayment types?

Yes, asphalt-saturated felt underlayment can have issues such as water absorption, wrinkling or premature deterioration if not up to standards or exposed to harsh conditions. Synthetic underlayments may have limitations such as lack of ASTM standards or potential warranty concerns from some roofing material manufacturers.

Does climate play a role in underlayment selection?

Absolutely. Extreme temperature fluctuations are a deciding factor in choosing materials like rubberized asphalt or synthetics. The underlayment should be matched with the roof type and local environmental conditions to ensure optimal protection and extend the roof’s service life.

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Justin Coltharp

Justin Coltharp

Pinnacle Roofing Group Owner