What Is Roof Underlayment?

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Roof Underlayment Basics

Roof underlayment is a crucial component of any roofing system, providing an extra layer of protection against moisture and leaks. It plays an essential role in preserving the integrity of your roof, especially in Colorado’s harsh weather conditions.

Many homeowners only think about the outermost layer of their roof, but there’s much more to it than just shingles or metal panels. A roof is made up of multiple layers, each serving a specific purpose to ensure durability and longevity. These layers include the roof’s skeleton, the roof deck, and the roof underlayment.

  • Roof Skeleton: The structural framework of the roof, made from rafters or trusses, providing support and shape.
  • Roof Deck: A solid layer of plywood, OSB, or step sheathing attached to the skeleton to add stability.
  • Roof Underlayment: A protective layer that sits between the roof deck and the outer roofing material, shielding the roof from moisture and leaks.

Why Is Roofing Underlayment Important?

Colorado’s extreme weather, including heavy snowfall, strong winds, and hail, can take a toll on your roof. While shingles or metal panels provide the first line of defense, they are not entirely waterproof—especially where they overlap. Roofing underlayment is the essential secondary barrier that protects your home from leaks, preventing moisture from reaching the roof deck and causing structural damage.

Certain areas of a roof—such as valleys, dormers, and hips—are especially vulnerable to leaks. For example, in Colorado, the freeze-thaw cycle can cause ice dams to form in roof valleys, leading to water seeping underneath the shingles and into the home. Roofing underlayment adds an extra layer of protection in these spots, ensuring that your home remains dry and damage-free during Denver’s intense snowstorms and summer downpours.

Types of Roofing Underlayment

There are three primary types of roof underlayment: felt, synthetic, and self-adhered. Each type offers unique benefits, and the best choice depends on your budget, roof design, roofing material, and Colorado’s climate.

Felt Roofing Underlayment

Also called tar paper or felt paper, this is the oldest type of underlayment and was widely used before synthetic alternatives became available. It is made from an organic mat or cellulose base saturated with asphalt to enhance water resistance.

  • Available in two weights:
    • No. 15 Felt: Weighs 15 pounds per 100 square feet. Best for lightweight roofing projects but prone to tearing.
    • No. 30 Felt: Heavier at 30 pounds per 100 square feet, making it more durable than No. 15 felt.

Pros:

  • Budget-friendly option.

Cons:

  • Heavy and difficult to install.
  • Prone to tearing in high winds or under stress.
  • Absorbs moisture, leading to wrinkles that affect shingle installation.
  • May void some roofing manufacturer warranties that require synthetic underlayment.

Synthetic Roofing Underlayment

The most popular underlayment choice today, synthetic underlayment is made from moisture-resistant polymers that provide superior protection compared to felt.

Pros:

  • Extremely durable and tear-resistant.
  • Lightweight and easier to install than felt.
  • Repels moisture instead of absorbing it, preventing mold growth.
  • Provides better UV resistance if left exposed.
  • Slip-resistant surfaces enhance safety during installation.

Cons:

  • Higher cost compared to felt underlayment.

Self-Adhered Underlayment

Considered the premium option and often referred to as ice and water shield, self-adhered underlayment contains rubber and asphalt polymers, creating a waterproof seal that adheres directly to the roof deck. The sealant also covers nail holes, making it an excellent choice for Colorado homes that experience heavy snowfall and ice dams.

Best for: Leak-prone areas such as valleys, chimneys, skylights, vents, and eaves. Can also be used for full-roof coverage for maximum protection.

Pros:

  • Provides a 100% waterproof barrier, unlike felt and synthetic underlayment, which offer water resistance but do not create a completely sealed surface.
  • Seals around nails for enhanced leak resistance.
  • Extremely durable and long-lasting.
  • Slip-resistant surface for safer installation.

Cons:

  • The most expensive underlayment option.

Choosing the Right Roofing Underlayment

Whether you’re replacing an old roof or installing a new one, selecting the right underlayment is just as important as choosing the roofing material itself. The right choice can significantly impact the longevity and maintenance needs of your roof, saving you from costly repairs in the future. Consider the following factors:

  • Budget: If cost is a primary concern, felt underlayment is the most affordable option.
  • Durability: If you want a longer-lasting, low-maintenance solution, synthetic underlayment is the best choice.
  • Climate Considerations: In areas like Denver, where harsh winters and heavy snowfall are common, self-adhered underlayment offers the best protection.

Maxx Roof LLC: Your Trusted Roofing Expert in Denver

At Maxx Roof LLC, we understand the unique challenges that Colorado’s climate presents. That’s why we use only the highest quality materials and expert installation techniques to ensure your roof remains strong and leak-free for years to come. Whether you need a roof replacement, repair, or new installation, our team of skilled professionals is here to help you choose the best roofing underlayment for your home.

Contact us today for a free consultation and estimate, and experience the superior craftsmanship and industry-leading warranties that set Maxx Roof LLC apart from the rest, and let us provide the reliable roofing solutions you deserve!

We Service All Of Denver And Nearby Cities

Our service area covers Denver, CO and all nearby cities, so if your home or commercial property is located anywhere in the Denver region, give us a call today. If your property is located in the mountains or outside of our normal service area, we may be able to provide service still, so don’t hesitate to give us a call and discuss your roofing needs.

At Maxx Roof LLC, we provide roof underlayment services across Denver, CO and the neighboring areas. Some of the nearby cities that we service are: 

  • Denver, CO
  • Lakewood, CO
  • Castle Rock, CO
  • Arvada, CO
  • Aurora, CO
  • Westminster, CO
  • Boulder, CO, Broomfield, CO
  • Littleton, CO
  • Englewood, CO
  • Centennial, CO
  • Parker, CO
  • Longmont, CO
  • Lafayette, CO
  • Superior, CO
  • Thornton, CO
  • Wheat Ridge, CO
  • Golden, CO
  • Morrison, CO
  • Brighton, CO
  • Commerce City, CO
  • Watkins, CO
  • Highlands Ranch, CO
  • Lone Tree, CO
  • Edgewater, CO
  • Gunbarrel, CO
  • Firestone, CO
  • Erie, CO
  • Strasburg, CO
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