Roofing felt is a critical component in roofing systems, serving as a protective layer between the roof deck and shingles or other roofing materials. It provides waterproofing, reduces the risk of leaks, and enhances the roof’s durability. Understanding the various types of roofing felt available in the market helps homeowners and contractors choose the right material tailored to specific needs, climates, and budgets.
| Type of Roofing Felt | Material | Weight | Benefits | Best Application |
|---|---|---|---|---|
| Asphalt-Saturated Felt (Organic) | Organic fibers (often cotton or wood pulp) | 15 lb or 30 lb | Good water resistance, easy to work with, economical | Traditional residential roofing |
| Fiberglass-Based Felt | Fiberglass mat with asphalt saturation | 15 lb or 30 lb | Stronger, more fire-resistant, durable | Commercial roofs, high-wind areas |
| Synthetic Underlayment | Polypropylene or polyester materials | Varies (lighter than traditional felt) | Lightweight, tear-resistant, better UV protection | Modern residential and commercial roofs |
Organic Asphalt-Saturated Felt
Organic roofing felt is one of the oldest and most traditional types used. Made primarily from natural fibers such as cotton or wood pulp saturated with asphalt, it provides a solid waterproof barrier. Available in 15 lb and 30 lb weights, the 30 lb felt offers better protection due to its thicker and denser construction.
This type of felt is easy to cut and lay down, inviting less material waste during installation. However, it tends to absorb moisture if left exposed for extended periods, which can reduce its effectiveness. Its affordability and traditional properties make it common in many residential applications.
Fiberglass-Based Roofing Felt
Fiberglass roofing felt integrates a fiberglass mat saturated with asphalt, replacing organic fibers to improve durability. It resists tearing better and provides superior fire resistance compared to organic felt. This type of felt is also produced in 15 lb and 30 lb variants.
The main advantages include greater dimensional stability, making it less prone to wrinkling or wrinkling during installation. Fiberglass felt is often preferred in commercial roofing and environments susceptible to strong winds or extreme weather.
Synthetic Roofing Underlayment
Synthetic roofing underlayment is rapidly gaining popularity as an advanced alternative to traditional felt. Constructed from polypropylene or polyester materials, these underlayments are significantly lighter and more durable.
Synthetic types offer excellent resistance to tears and UV exposure, extending their lifespan when roofs have prolonged exposure before shingle application. Additionally, they generally provide better waterproofing capabilities, making them ideal for modern construction requiring high-performance materials.
Advantages of Synthetic Underlayment
- Lighter weight eases handling and installation
- Superior tear resistance reduces damage during installation
- More effective waterproofing prolongs roof life
- UV protection allows safe exposure time before covering
- Improved slip resistance enhances safety for roofers
Weight Categories and Their Implications
Roofing felt weight, traditionally expressed in pounds (15 lb or 30 lb), is an indicator of thickness and density, not actual weight per square. The 30 lb felt is thicker and preferred where more protection is needed, providing additional durability and resistance to tearing.
The lighter 15 lb variant is easier to handle and install but generally less durable, making it suitable for roofs in mild climates or temporary protection. Synthetic underlayments, while lighter, often exceed performance characteristics of 30 lb felt, offering a compelling choice in durability and handling.
Choosing the Right Type of Roofing Felt
Selecting the best roofing felt depends on multiple factors including climate, building codes, and roof design. For example, organic felt works well in less extreme weather and budget-conscious projects. Fiberglass felt suits areas requiring better fire resistance and mechanical durability.
Synthetic underlayments are ideal when long-term durability, enhanced waterproofing, and UV resistance are priorities, especially in modern or commercial constructions.
Additional Types of Roof Underlayment
Besides felt and synthetic options, specialized underlayments such as self-adhering rubberized asphalt membranes exist, providing superior waterproofing around high-risk areas like roof valleys and penetrations. These are often used in combination with traditional or synthetic felt.
Installation Considerations
Proper installation is crucial for any roofing felt type. It requires overlapping sheets to prevent water infiltration, securing with roofing nails or staples, and ensuring coverage extends beyond edges to protect vulnerable areas. Failure to install felt correctly can compromise roofing efficiency and lead to premature failure.
Environmental Impact and Sustainability
Traditional organic felt has environmental concerns due to the use of natural fibers and asphalt. Fiberglass-based felt reduces some natural resource use but still relies on asphalt saturants. Synthetic underlayments, often made of recyclable plastics, can offer a more sustainable option but vary by manufacturer and material composition.
Cost Comparison of Roofing Felt Types
| Type | Average Cost per Square (100 sq ft) | Longevity | Durability |
|---|---|---|---|
| Organic Asphalt-Saturated Felt | $15 – $30 | 5-10 years | Moderate |
| Fiberglass-Based Felt | $20 – $35 | 10-15 years | High |
| Synthetic Underlayment | $40 – $60 | 15-25 years | Very High |