By: Boxer Exteriors • Aug 4, 2025 • 11 min. read
Weather extremes in the Chicagoland area necessitate a robust roofing underlayment, a vital shield against the elements and crucial for prolonging roof life. Discover the key types and their benefits.
Table of Contents
- 1. Definition and Function of Roof Underlayment
- 2. Types of Roof Underlayment
- 3. Importance of Underlayment
- 4. Factors to Consider When Choosing Roof Underlayment
- 5. Installation Considerations
- 6. Additional Considerations
- 7. Frequently Asked Questions (FAQ)
In the ever-changing climate of Illinois, roofing underlayment serves as a critical component of any roofing system. This layer, hidden beneath the shingles, acts as a secondary barrier that protects your home from water damage and enhances the overall longevity of your roof. Understanding the significance and the main types of underlayment can help homeowners make informed decisions when it comes to roof replacement or installation.
Definition and Function of Roof Underlayment
Roof underlayment is a layer of material installed between the roof deck and the shingles. Its primary role is to provide a moisture barrier, safeguarding the home from water infiltration which can lead to mold growth, rot, and structural damage. Additionally, it acts as an extra layer of protection against harsh weather conditions prevalent in Chicagoland, such as heavy rain, snow, and ice. Common materials used for underlayment include asphalt-saturated felt, synthetic fabrics, and rubberized asphalt, each offering different levels of water resistance and durability.
Types of Roof Underlayment
- Asphalt-Saturated Felt. This traditional type of underlayment, made from either organic or fiberglass felt saturated with asphalt, comes in two main types: 15-pound and 30-pound felt. The numbers refer to the weight of the asphalt saturation per 100 square feet. While a 15-pound felt is lighter and less durable, a 30-pound felt offers better protection and water resistance, making it a preferable choice in Illinois’ variable weather conditions. Despite its water-resistant properties, asphalt-saturated felt can absorb water, and thus, may warp over time. Installation typically involves rolling out the felt over the roof deck and fastening it with staples or nails.
- Synthetic Underlayment. Constructed from woven or spun polyethylene or polypropylene, synthetic underlayment is lighter and stronger than felt. It is highly resistant to mold growth, tearing, and water penetration, making it an excellent choice for Chicagoland homes. Its durability ensures that it can withstand extreme weather without deteriorating or breaking down. Installation involves similar techniques to felt but often includes a self-adhering surface to improve stability and water resistance.
- Rubberized Asphalt Underlayment. Offering the highest level of water resistance, rubberized asphalt underlayment is an adhesive product with rubber polymers and asphalt. This type is ideal for areas prone to ice dams and wind-driven rain, common in Chicagoland. Rubberized asphalt can also self-seal around nails, providing superior leak protection. Types vary from non-modified to polymer-modified bitumen, with the latter offering greater flexibility and temperature resistance.
Selecting the right type of roofing underlayment is crucial for ensuring the durability and efficiency of your roof in Illinois. Each type of underlayment offers unique benefits and is suited for different environmental conditions and roofing materials. Homeowners should consult with a professional roofing contractor to discuss the best options tailored to their specific needs and local building codes.
Importance of Underlayment
Roof underlayment in Chicagoland plays a pivotal role in safeguarding homes from the elements. It acts as a moisture barrier, essential in preventing water seepage that can lead to costly damages like mold and rot. Beyond its barrier capabilities, underlayment also provides an additional layer of protection against the harsh winter weather, particularly ice and snow, which are prevalent in Illinois. This added layer helps prevent ice dams and water pooling, which can infiltrate roof materials and compromise the structure.
Factors to Consider When Choosing Roof Underlayment
Selecting the right underlayment for your roof in Chicagoland requires considering several critical factors:
- Climate Considerations: The seasonal extremes—intense summers and frigid winters—demand a durable underlayment that can withstand thermal expansion and contraction without deteriorating.
- Type of Roof: The type of shingles or roofing material used also influences underlayment choice. For instance, asphalt shingles, common in Chicagoland, work well with asphalt-saturated felt, while metal roofs often require synthetic underlayment for better heat resistance.
- Durability Requirements: Depending on the roof’s expected lifespan and the typical weather conditions it will face, the durability of the underlayment must be aligned. Synthetic underlayment, for instance, offers superior tear resistance and longevity, ideal for Chicagoland’ variable climate.
- Cost Considerations: While budget constraints are always a concern, investing in a higher-quality underlayment can provide long-term savings by reducing the need for repairs and extending the roof’s overall lifespan.
Installation Considerations
Proper installation of roof underlayment is crucial to ensure its effectiveness and durability:
- Importance of Proper Installation: Incorrect installation can lead to gaps and overlaps that compromise the underlayment’s ability to protect the roof. Chicagoland roofing contractors must adhere to local building codes and manufacturers’ guidelines to ensure optimal performance.
- Slope Limitations: The slope of the roof dictates the type of underlayment and the method of installation. Steeply sloped roofs, for example, may require different underlayment than flat or low-slope roofs due to the increased risk of water run-off and potential pooling.
- Fastening Methods: The choice of fasteners (nails or staples) and their spacing are critical to securing the underlayment properly. In areas prone to high winds, as often experienced in Chicagoland, enhanced fastening techniques might be necessary.
- Edge Treatments: Special attention must be paid to the treatment of roof edges and valleys where water runoff is concentrated. Proper sealing and overlapping are essential to prevent water ingress, which can be particularly damaging during the freeze-thaw cycles in Illinois.
Choosing and installing the right roofing underlayment in Chicagoland is a complex but crucial task that significantly affects the roof’s functionality and longevity. Homeowners should work with experienced roofing contractors to ensure that their roofing underlayment is appropriately selected and installed, providing them with peace of mind against the unpredictable Illinois weather.
Additional Considerations
When installing or replacing roofing underlayment in Chicagoland, it’s not just about choosing the right materials—it’s also essential to navigate the regulatory landscape:
- Building Permits and Code Compliance: Ensuring that your roofing project complies with local building codes is crucial. In Chicagoland, this might involve securing permits and adhering to specific standards that regulate underlayment types and installation methods, tailored to withstand local weather conditions.
- Warranty Information: Most underlayment products come with a manufacturer’s warranty that can protect against defects. However, the validity of these warranties often depends on proper installation according to manufacturer guidelines—another reason to use skilled and certified roofing contractors.
- Importance of Choosing a Reputable Roofing Contractor: The durability of your roofing underlayment heavily depends on the quality of the installation. It’s vital to select a contractor who is not only licensed and insured but also has a robust track record of installing high-quality roofs across Illinois.
Roof underlayment is a key component of your home’s defense system against the elements. It serves as an essential moisture barrier, provides additional protection from severe weather, and contributes to the overall longevity of your roof. In Chicagoland, where weather conditions can be particularly harsh, choosing the right type of underlayment and ensuring it’s properly installed is paramount.
Frequently Asked Questions (FAQ)
- Q: What is the best type of underlayment for Chicagoland weather?
- A: Synthetic underlayment is often recommended due to its superior durability and resistance to moisture.
- Q: How often should underlayment be replaced?
- A: Underlayment should be inspected whenever the roof is replaced, and any signs of damage or wear could indicate that it’s time for a replacement.
- Q: Can I install a new underlayment over the old underlayment?
- A: It is generally recommended to remove old underlayment to ensure the new layer performs effectively and adheres properly to the roof deck.
For more detailed guidance on selecting and installing the right roofing underlayment for your home in Illinois, consult with us, as we are experienced roofing contractors. Reach out today at 630-570-0269 or email info@boxerexteriors.com to discuss your roofing needs and to ensure your home remains protected through every season. Remember, the right underlayment is your roof’s best ally against the unpredictable Illinois climate.
