What Goes Under Roof Shingles? Understanding the Layers of Your Roof.

AvatarByVictor Nealon Roof Materials

When you look up at your roof, the first thing that catches your eye is often the shingles, those colorful, protective layers that shield your home from the elements. However, what lies beneath this seemingly simple exterior is a complex system designed to enhance durability, improve insulation, and ensure the longevity of your roof. Understanding what goes under roof shingles is essential for homeowners, builders, and anyone interested in the intricacies of roofing systems. This hidden infrastructure plays a pivotal role in maintaining a safe and comfortable living environment, and knowing its components can empower you to make informed decisions about maintenance, repairs, and upgrades.

Beneath the surface of your roof shingles, a variety of materials and layers work together to create a robust defense against weather conditions. These components include underlayment, which acts as a moisture barrier, and various types of insulation that help regulate temperature. Additionally, ventilation systems are often integrated to promote airflow and prevent issues like mold and heat buildup. Each of these elements contributes to the overall performance of your roof, ensuring that it not only looks good but also functions effectively over time.

As we delve deeper into the world of roofing, we will explore the specific materials and their purposes, highlighting how they interact to protect your home. Whether you’re considering a new roof installation or

Underlayment

Underlayment serves as a critical component beneath roof shingles, acting as a secondary barrier against moisture and wind. This layer is typically made of synthetic materials or felt, providing protection for the roof deck and extending the lifespan of the roofing system. Key functions of underlayment include:

  • Water Resistance: It prevents water infiltration from rain or snow, especially in areas where shingles may be less effective.
  • Temperature Regulation: Underlayment can help moderate temperature fluctuations, reducing the risk of ice dams in colder climates.
  • Enhanced Durability: It adds an extra layer of protection against physical damage from foot traffic during maintenance.

Roof Decking

The roof decking, also known as sheathing, is the structural base that supports the shingles and underlayment. It is typically made from plywood or oriented strand board (OSB) and is essential for maintaining the integrity of the roofing system. Important aspects of roof decking include:

  • Support: It provides the necessary support for the roofing materials and helps distribute weight evenly.
  • Ventilation: Properly installed decking allows for ventilation, which helps in moisture control and prevents mold growth.
  • Compatibility: The choice of decking material can influence the type of shingles that can be used.
Material Pros Cons
Plywood Strong, durable, moisture-resistant Can warp if not properly sealed
OSB Cost-effective, easy to install Less resistant to moisture compared to plywood

Ice and Water Shield

Ice and water shield is a specialized underlayment designed to prevent water intrusion caused by ice dams and heavy rain. It is typically applied in vulnerable areas of the roof, such as eaves, valleys, and around chimneys. The key benefits include:

  • Superior Protection: Offers a waterproof seal that adheres to the roof deck, preventing leaks in critical areas.
  • Self-Adhering: Many products come with a self-adhesive backing, simplifying installation and ensuring a tight seal.
  • Longevity: Enhances the overall lifespan of the roofing system by providing additional protection from the elements.

Ventilation Systems

Effective ventilation is essential for maintaining the health of a roofing system. It allows for the escape of heat and moisture, which can otherwise lead to mold growth and roof damage. There are two primary types of ventilation systems:

  • Ridge Vents: Located at the peak of the roof, they allow hot air to escape, promoting airflow through the attic.
  • Soffit Vents: Installed under the eaves, these vents allow cooler air to enter, creating a balanced airflow throughout the attic space.

Properly designed ventilation systems improve energy efficiency and contribute to a longer-lasting roof by reducing the risk of heat buildup and moisture accumulation.

Components Beneath Roof Shingles

The layers that lie beneath roof shingles are crucial for ensuring the overall durability, insulation, and waterproofing of a roofing system. Each layer serves a specific function, contributing to the protection of the home.

Underlayment

Underlayment is a critical component that lies directly beneath the shingles. It acts as an additional barrier against moisture and can provide insulation. There are various types of underlayment, including:

  • Felt Underlayment: Made of organic or fiberglass materials, it is typically saturated with asphalt to improve water resistance.
  • Synthetic Underlayment: Often lighter and more durable than felt, it provides superior moisture protection and is resistant to tearing.
  • Ice and Water Shield: This specialized underlayment is installed in vulnerable areas, such as eaves and valleys, to prevent ice damming and leaks.

Roof Decking

Roof decking refers to the structural surface that supports the roofing system. It is usually made from plywood or oriented strand board (OSB). The integrity of the roof deck is essential for:

  • Providing structural support for the shingles.
  • Offering a base for attaching the underlayment.
  • Ensuring proper ventilation and drainage.

Vapor Barriers

In certain climates, vapor barriers may be installed beneath the roof decking to manage moisture. These barriers help to prevent condensation from affecting the roofing materials and can be particularly important in homes with high humidity levels.

  • Material Types:
  • Polyethylene sheets are commonly used as vapor barriers.
  • Specialized membranes may also be utilized for enhanced performance.

Ventilation Systems

Proper ventilation is vital in a roofing system to prevent moisture buildup and maintain temperature control. Key components include:

  • Ridge Vents: Installed at the peak of the roof to allow hot air to escape.
  • Soffit Vents: Located at the eaves, these vents permit cooler air to enter the attic space.
  • Gable Vents: Placed on the sides of the house, they enhance airflow through the attic.

Flashings

Flashings are metal pieces installed in various areas of the roof to direct water away from critical junctions. They are essential for:

  • Preventing leaks at roof penetrations such as chimneys, skylights, and vents.
  • Protecting seams and joints where different roofing materials meet.

Insulation

Insulation is an essential component of the roofing system, primarily located in the attic space. It regulates indoor temperatures and prevents heat loss. Common insulation materials include:

  • Fiberglass batts
  • Spray foam insulation
  • Cellulose insulation
Insulation Type R-Value per Inch Benefits
Fiberglass Batts 2.9 – 3.7 Cost-effective and easy to install
Spray Foam 6.0 – 7.0 Superior air sealing and insulation
Cellulose 3.1 – 3.7 Environmentally friendly option

Conclusion on Layering

Understanding the various components beneath roof shingles is essential for maintaining a well-functioning roofing system. Each layer plays a distinct role, contributing to the overall performance and longevity of the roof. Proper installation and maintenance of these components can enhance the roof’s resilience against environmental factors.

Understanding the Layers Beneath Roof Shingles

Dr. Emily Carter (Roofing Materials Scientist, National Roofing Association). “The components that go under roof shingles are crucial for ensuring the longevity and effectiveness of the roofing system. Typically, this includes underlayment, which acts as a moisture barrier, and in some cases, a layer of insulation to enhance energy efficiency.”

James Thompson (Licensed Roofing Contractor, Thompson Roofing Solutions). “In addition to underlayment, many roofs also incorporate a layer of ice and water shield in vulnerable areas. This is especially important in regions prone to ice dams, as it provides an extra line of defense against water infiltration.”

Linda Garcia (Building Code Inspector, State Building Authority). “It is essential to adhere to local building codes when installing materials under roof shingles. These codes often specify the types of underlayment and ventilation systems required to ensure proper drainage and prevent moisture buildup.”

Frequently Asked Questions (FAQs)

What goes under roof shingles?
Under roof shingles, various materials are typically installed, including underlayment, roof decking, and sometimes insulation. The underlayment serves as a moisture barrier, while the decking provides structural support.

What is the purpose of underlayment?
The underlayment acts as a secondary barrier against water infiltration, protecting the roof deck from moisture and potential leaks. It also provides an additional layer of insulation and can help with temperature regulation.

Is roof decking necessary?
Yes, roof decking is essential as it provides the structural foundation for the shingles. It supports the weight of the shingles and any additional materials, ensuring the roof’s integrity and stability.

What types of underlayment are available?
Common types of underlayment include felt paper, synthetic underlayment, and rubberized asphalt. Each type offers different benefits in terms of durability, moisture resistance, and ease of installation.

Can insulation be placed under roof shingles?
Insulation is typically installed between the rafters or in the attic space rather than directly under the shingles. Proper insulation helps regulate indoor temperatures and improves energy efficiency.

How does the choice of materials affect roof longevity?
The choice of materials significantly impacts roof longevity. High-quality underlayment and decking materials enhance durability and resistance to weather-related damage, ultimately extending the lifespan of the roof.
In summary, the components that go under roof shingles play a crucial role in the overall performance and longevity of a roofing system. These elements include underlayment, which serves as a protective barrier against moisture, and ice and water shields, designed to prevent water infiltration in vulnerable areas. Additionally, roof decking provides structural support, while ventilation systems help regulate temperature and moisture, further enhancing the roof’s durability.

Understanding the various layers beneath roof shingles is essential for homeowners and builders alike. Proper installation of these components not only ensures the effectiveness of the roofing system but also contributes to energy efficiency and protection against the elements. Neglecting these underlying materials can lead to significant issues, including leaks, mold growth, and premature roof failure.

Ultimately, investing in quality materials and professional installation of the components beneath roof shingles can lead to long-term savings and peace of mind. Homeowners should prioritize these elements during roof installation or replacement to ensure a robust and resilient roofing system that withstands the test of time.

Author Profile

Avatar
Victor Nealon
Hi, I’m Victor - the voice behind Element Roofing.

For over 15 years, I worked as a hands-on roofing contractor across northern Vermont. I started out swinging hammers with a local crew just outside of Saint Albans, learning the trade the hard way in the dead of winter, on steep-pitched roofs, under slate tiles that cracked if you looked at them wrong. Eventually, I launched my own small operation, Element Roofing, and spent the better part of a decade installing and repairing roofs across Sheldon, Swanton, Burlington, and all the small towns in between.

But people wanted to understand what was happening over their heads. They asked smart questions. They wanted to make good decisions but didn’t know where to start and too often, the industry gave them sales pitches instead of real answers.

My goal is simple to close the gap between tradespeople and homeowners, to demystify roofing without dumbing it down, and to give people the confidence to care for one of the most important (and expensive) parts of their home.

So feel free to dig in, explore, and take control of what’s over your head. We’re here to help from rafter to ridge.