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September 30, 2024When it comes to roofing, most people think about the shingles or tiles that cover the surface. However, there’s a critical component that lies beneath the visible layer, often overlooked but just as important: the roof underlayment.
This protective layer plays a significant role in the performance and longevity of your roof. Whether you’re planning a roof replacement or a new installation, understanding roof underlayment is key to ensuring your home remains protected against the elements.
Let’s examine roof underlayment, its importance, and what types are available.
What Is Roof Underlayment?

Roof underlayment is a protective barrier installed directly on your roof deck before the final roofing material, whether shingles, tiles, or metal, is applied. It acts as an extra line of defense, protecting against water infiltration, especially during severe weather events like heavy rain, snow, or ice.
The main purpose of underlayment is to protect the roof from leaking, forming mold, and water infiltration. It’s an additional layer of security between the roof deck and the outer material.
Read also: Pros and Cons of Roof Coatings for Flat and Low-Slope Roofs
Why Roof Underlayment Is Important
Roof underlayment plays a variety of important roles that help preserve the integrity of your roof and the safety of your home. Here are some of the benefits:
Waterproofing

Even if your outer roofing material is properly installed, there’s always the possibility that water could sneak through. The underlayment serves as a waterproof barrier to catch any water that passes through the roof covering, stopping it before it can reach your home’s interior.
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Protection Against Wind-Driven Rain
During storms, wind can force rain beneath shingles or tiles. Without underlayment, that water could penetrate the roof deck, causing leaks. Underlayment offers an additional layer of protection against these elements.
Ice and Snow Barrier

In the winter, ice dams can form on roofs, causing water to back up beneath shingles. Underlayment prevents this water from penetrating the roof, protecting the structure from potential damage.
Read also: How to Prevent Ice Dams on Your Roof in Rhode Island Winters
Secondary Protection During Installation
If you’re replacing your roof, there may be a period where your home is exposed before the new roofing materials are installed. Underlayment helps protect your home from rain and other elements during this transition period.
Increased Fire Resistance
Certain types of underlayment, such as those made from synthetic materials, can improve your roof’s fire resistance. This is an extra layer of safety for your home.
Types of Roof Underlayment

There are three types of roof underlayment: asphalt-saturated felt, synthetic underlayment, and rubberized asphalt. Each type offers unique benefits. Understanding their differences will help you choose the right one for your specific needs.
Asphalt-Saturated Felt (Traditional Underlayment)

Asphalt-saturated felt is generally known as “Felt Paper” or “Tar Paper.” It has been the standard underlayment for many years. It is made from a blend of organic or fiberglass materials and saturated with asphalt. This underlayment provides a reasonable level of water resistance.
Pros
- Affordable and widely available
- Provides adequate protection for many residential roofs
- Compatible with most types of roofing materials
Cons
- Not as durable as newer synthetic materials
- Can tear or wrinkle during installation
- Absorbs water, which can lead to moisture buildup over time
Felt is often used for traditional residential homes, but synthetic underlayment options are gradually replacing it.
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Synthetic Underlayment (Preferred Choice)

Synthetic underlayment has become the most popular choice in modern roofing due to its superior performance and durability. It is made from various polymers and offers enhanced water resistance and tear strength compared to asphalt-saturated felt.
Pros
- Lightweight and easy to install
- Highly resistant to water and moisture
- Resistant to tearing and wrinkling
- Longer lifespan compared to felt
- Some options include anti-slip surfaces for safer installation
Cons
- Higher upfront cost than asphalt-saturated felt
- Different brands and quality levels may offer varying levels of performance
Synthetic underlayment is ideal for most residential and commercial roofing applications, providing long-lasting protection against water damage.
Read also: Understanding Roof Ventilation: Why It Matters for Your Home’s Longevity

Rubberized asphalt underlayment is the premium choice for areas that require additional waterproofing, such as valleys, eaves, and low-slope sections of a roof. This type of underlayment is designed with a self-adhesive backing and includes a rubberized component, making it fully waterproof.
Pros
- Fully waterproof, ideal for high-moisture areas
- Self-sealing around nails and fasteners, providing extra protection against leaks
- Great for ice and water shield applications
Cons
- More expensive than other underlayment options
- Typically used in combination with other types of underlayment for specific roof areas
This option is often recommended in areas with extreme weather conditions.

Read also: The Benefits of Cool Roofing: Reducing Energy Costs in Rhode Island Homes
Choosing the Right Underlayment for Your Roof
When deciding on the best underlayment for your roof, it’s important to consider several factors:
Climate
Homes in areas with heavy rain, snow, or ice may benefit from more durable underlayment materials like synthetic or rubberized asphalt. If you live in a milder climate, traditional felt may be sufficient.
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Roof Type and Slope
Low-slope roofs are more prone to water pooling, which can increase the risk of leaks. In such cases, a more durable underlayment is recommended. For steep-slope roofs, synthetic underlayment provides strong protection and is easy to install.

Read also: Unlocking the benefits of EPDM membrane roofing systems for your home
Budget
While synthetic and rubberized asphalt underlayments come with a higher price tag, they offer longer-lasting protection. Balancing cost with performance is key to finding the right fit for your roofing needs.
Read also: Your options when you need a new roof but can’t afford it
Roofing Material
The type of roofing material you plan to install will also influence your choice of underlayment. Some materials, like metal roofing, may require specific types of underlayment for compatibility and performance.
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Conclusion
Roof underlayment is an essential part of any roofing system, providing the unseen but crucial protection your roof needs to stand up to the elements. Whether you’re dealing with rain, snow, ice, or strong winds, choosing the right underlayment can save you from unwanted damage. It can also increase the performance and longevity of your roof.
Understanding the different types of underlayment ensures that your roof is fully equipped to handle whatever Mother Nature throws its way. If you’re planning a new roof or need to replace an existing one, make sure to discuss underlayment options with your roofing contractor to ensure you’re making the best choice for your home.