The Role of Underlayment in Your Roofing System


While shingles or other roofing materials are what you see on the surface of your roof, the underlayment plays a critical, yet often overlooked, role in your roofing system. Underlayment is a protective layer installed directly onto the roof deck before the final roofing material is applied. In this guide, we’ll explore the importance of underlayment in your roofing system and its role in protecting your home.

1. Waterproofing

One of the primary functions of underlayment is to provide an additional layer of waterproofing for your roof. Even if your main roofing material, such as asphalt shingles or metal panels, were to fail or be damaged, the underlayment serves as a secondary barrier against water infiltration.

2. Protection Against Wind-Driven Rain

Underlayment helps to prevent wind-driven rain from penetrating the roof deck and causing water damage to the underlying structure of your home. It acts as a barrier, keeping moisture out and protecting your home’s interior from leaks and water damage.

3. Added Insulation

Some types of underlayment, such as synthetic or rubberized materials, provide additional insulation for your roof. This can help to improve the energy efficiency of your home by reducing heat loss and preventing cold air from entering through the roof.

4. Moisture Control

In addition to preventing water from entering your home, underlayment also helps to control moisture levels within the roof system itself. By allowing moisture to escape, underlayment helps to prevent mold, mildew, and rot from forming in the attic and roof deck.

5. Protection During Roof Installation

During the installation of your new roof, underlayment provides temporary protection against the elements until the final roofing material can be installed. This helps to prevent water damage to the roof deck and interior of your home during the construction process.

Types of Underlayment

There are several types of underlayment available, each with its own unique properties and advantages:

  • Asphalt-Saturated Felt: This traditional underlayment is made from organic or fiberglass material and is impregnated with asphalt for waterproofing.
  • Synthetic Underlayment: Made from materials such as polyethylene or polypropylene, synthetic underlayment is lightweight, durable, and resistant to tearing and wrinkling.
  • Rubberized Underlayment: Rubberized underlayment offers superior waterproofing and is highly resistant to UV rays and weathering.


While often out of sight, underlayment plays a crucial role in protecting your home from water damage and ensuring the longevity of your roofing system. By providing an additional layer of waterproofing, insulation, and moisture control, underlayment helps to keep your home safe, dry, and comfortable for years to come. If you’re planning to install a new roof or replace an existing one, be sure to discuss your underlayment options with your roofing contractor to ensure that you choose the right material for your home and climate.

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