What Kind of Underlayment Should Go Under A Residential Roof?

Asphalt shingles, metal, tile, cedar shake, slate – these roof coverings have proven to be effective barriers against harsh weather conditions, ensuring the roofing system stands up to anything Mother Nature throws at it. What you may not know, however, is that the secret weapon against moisture infiltration and water damage is not the pretty covering you see from the street, but what lies beneath – the roofing underlayment. 

In Florida, having quality underlayment is one way of creating a storm-proof roof. Since hurricanes and windblown debris significantly damage the roof covering and expose your home to water intrusion, the state has stricter building codes specific to roofing.

An Overview of Roofing Underlayment

Roof underlayment is a water-resistant or waterproof membrane installed between the roof deck and roof covering. It serves as a barrier to prevent water from damaging the roof deck and flooding into a house when the roof covering is ripped off during a storm

Other functions of roofing underlayment include:

  • Protecting the roof covering from resins that bleed out of the decking
  • Preventing unevenness in the roof decking from telegraphing through the roof covering, especially shingles
  • Extending the life of the roof
  • It’s typically required for the UL fire rating of roofing materials

Types of Underlayment Used in Residential Roofing

There are three main types of residential roofing underlayment:

Asphalt-Saturated Organic Felt Paper

One of the most common forms of underlayment used in residential roofing applications is asphalt-saturated felt paper. This low-cost, easy-to-install material is a blend of various paper-based sheets, asphalt, cellulose, and bitumen soaked in a waterproofing agent.

Asphalt-saturated felt is available in 15-pound and 30-pound thicknesses. Many roofers prefer the 30-pound felt because it is much thicker, stiffer, and more resistant to damage than the 15-pound felt. It also protects the roofing deck longer if exposed to the elements. Moreover, this underlayment material has proven effective in protecting a home from the severe impacts of flying debris, hailstones, and falling limbs. Many roofers have stopped using this material as better materials have become available for their customers. 


This is the most recently developed kind of roof underlayment. Synthetic underlayment is made from a mixture of asphalt-saturated base-mat and fiberglass. Thanks to the high asphalt saturation and fiberglass addition, it boasts superior strength, heat resistance, and water resistance.

High-quality synthetic underlayment has scrim reinforcement for additional slip resistance. This makes the underlayment easier to walk on during a roofing project. It also has an elasticity that allows the underlayment to contract and expand with temperature fluctuations without tearing. 

Synthetic underlayment rolls are thinner and lighter than other underlayments, adding less weight to the roof. They come with clear lines and overlap guides for fast installation. 

Other benefits of synthetic underlayment include:

  • Slow degradation rate and longer lasting
  • Wrinkle-free
  • Repels water and is inert to fungal and mold growth 
  • Resistant to UV damage
  • Highly durable and can be left exposed to the elements for an extended period of time

Rubberized Asphalt 

This roof underlayment is a premium option that provides the highest level of leak prevention. Rubberized asphalt underlayment is primarily made of rubber polymers and asphalt, which make it waterproof. In some cases, the underlayment may be fiberglass-reinforced.

This type of underlayment is called self-adhering underlayment because it has an adhesive backing on the lower side, protected by a membrane that is peeled off during installation. This special backing sticks directly to the roof deck, creating a waterproof seal between the underlayment and the roof deck. 

What’s more, the rubber-like qualities of this roofing underlayment allow it to seal well around nails. In other words, rubberized asphalt is a 100% waterproof underlay system.

The polyester or polyethylene content bonded to the upper surface provides a non-skid quality and enhanced weather resistance. Also, the underlay can easily expand and contract without breaking or cracking. These qualities make rubberized asphalt underlayment an excellent choice for your Florida home.

Roofing Underlayment Requirements in Florida

In the wake of Hurricane Michael, Florida made significant changes to the quality of roofing underlayment and standards for installation. The significant changes to the building codes are meant to increase protection on new roofs.

At Alan’s Roofing we adhere to all building codes and we’re here to help you build the safest, most reliable roof for your home. We’ve been fortifying Central Florida homes against the harsh weather for years. We always ensure the right materials are used, and the proper processes are followed when installing new roofs. If you need quality roof replacement services, contact us today for a free quote.