Synthetic vs. Felt Roofing Underlayment: Pros & Cons
When it comes to safeguarding your home from the elements, the roof is your first line of defense. A critical component of this defense system is the roofing underlayment—a layer installed between the roof deck and the shingles that provides additional protection against moisture and weather-related damage. Homeowners often face a choice between two primary types of underlayment: synthetic and felt. Understanding the differences between these materials is essential for making an informed decision that ensures the longevity and durability of your roof.
Understanding Roofing Underlayment
Roofing underlayment serves as a secondary barrier against water infiltration, protecting the roof deck from moisture that can lead to rot, mold, and structural damage. It also provides a uniform surface for shingle installation, enhancing the roofing system’s overall performance. The two main types of underlayment are felt (also known as tar paper) and synthetic.
Felt Underlayment: The Traditional Choice
Felt underlayment has been a staple in roofing for decades. It is typically made by saturating a base material, such as paper or fiberglass mat, with asphalt to create a water-resistant barrier. Felt underlayment is available in different thicknesses, commonly referred to as No. 15 and No. 30 felt, with the latter being thicker and more durable.
Advantages of Felt Underlayment
Cost-Effectiveness: One of the primary advantages of felt underlayment is its affordability. For homeowners on a tight budget, felt offers a cost-effective solution without compromising basic protection.
Availability: Due to its long-standing use in the industry, felt underlayment is widely available and familiar to many roofing contractors.
Disadvantages of Felt Underlayment
Durability Concerns: Felt underlayment is more susceptible to tearing, especially during installation or in high-wind conditions. This vulnerability can compromise the protective barrier it provides.
Moisture Absorption: Felt can absorb water, leading to wrinkling and buckling. These deformations can make it challenging to install shingles evenly and may reduce the underlayment’s effectiveness.
Limited Exposure Time: Felt underlayment should not be left exposed to the elements for extended periods, as it can degrade under prolonged UV exposure. This limitation requires timely installation of the final roofing material.
Weight and Handling: Felt is heavier than synthetic options, making it more cumbersome to handle during installation. The added weight can also contribute to increased labor time and costs.
Synthetic Underlayment: The Modern Alternative
Synthetic underlayment is a newer innovation in the roofing industry, designed to address some of felt’s shortcomings. It is typically made from polymers such as polypropylene or polyethylene, resulting in a lightweight, durable, and water-resistant material.
Advantages of Synthetic Underlayment
Enhanced Durability: Synthetic underlayment is highly resistant to tearing and can withstand harsh weather conditions, including high winds and UV exposure. This durability ensures a longer lifespan and reliable protection for your roof.
Moisture Resistance: Unlike felt, synthetic underlayment repels water and does not absorb moisture. This characteristic helps prevent issues like mold growth and structural damage to the roof deck.
Lightweight and Easy Installation: Synthetic underlayment’s lightweight nature makes it easier to handle and install. It often comes in larger rolls, covering more area with fewer seams, which can reduce installation time and labor costs.
Slip Resistance: Many synthetic underlayments feature a textured or slip-resistant surface, which provides better traction for installers and enhances safety during installation.
Extended Exposure Time: Synthetic underlayment can typically be left exposed to the elements for more extended periods without degrading, offering more flexibility in construction schedules.
Disadvantages of Synthetic Underlayment
Higher Cost: Synthetic underlayment’s superior performance and durability come at a higher price point compared to felt. Homeowners need to weigh the initial investment against the long-term benefits.
Vapor Permeability: Some synthetic underlayments are less breathable than felt, potentially trapping moisture beneath the roofing material if not adequately ventilated.
Key Considerations for Homeowners
When deciding between synthetic and felt underlayment, consider the following factors:
1. Climate and Weather Conditions: In areas prone to heavy rainfall, snow, or high winds, the enhanced durability and moisture resistance of synthetic underlayment may offer better protection.
2. Budget Constraints: If budget is a primary concern, felt underlayment provides a more affordable option. However, consider the potential for higher maintenance costs over time due to its susceptibility to damage.
3. Roofing Material Compatibility: Some roofing materials may perform better with a specific type of underlayment. Consult with your roofing contractor to ensure compatibility.
4. Installation Timeline: If there are expected delays in installing the final roofing material, synthetic underlayment’s ability to withstand extended exposure can be advantageous.
5. Building Codes and Manufacturer Warranties: Ensure that the chosen underlayment complies with local building codes and that it does not void any manufacturer warranties on your roofing materials.
Conclusion
Both synthetic and felt roofing underlayments have their respective advantages and disadvantages. Felt underlayment offers a cost-effective solution with a long history of use, but it comes with limitations in durability and moisture resistance. Synthetic underlayment provides superior performance in terms of strength, water resistance, and ease of installation, albeit at a higher cost.
As a homeowner, it’s essential to assess your specific needs, budget, and the environmental conditions of your location when choosing the appropriate underlayment for your roof. Consulting with a professional roofing contractor can provide valuable insights tailored to your situation, ensuring that your roof remains a robust barrier against the elements for years to come.
