Choosing the Best Felt Paper for Roofing: Essential Guide for Homeowners and Contractors
When installing or repairing a roof, selecting the right felt paper is critical for ensuring durability and weather resistance. Felt paper, also called roofing felt or tar paper, acts as an underlayment beneath shingles or other roofing materials, providing an additional layer of protection against moisture, wind, and temperature fluctuations. This article explores the best types of felt paper for roofing, key features to consider, and industry recommendations to help homeowners and contractors make informed decisions.
| Felt Paper Type | Material | Weight | Common Uses | Pros | Cons |
|---|---|---|---|---|---|
| Asphalt-Saturated Felt | Organic or Fiberglass mat soaked in asphalt | 15 lb or 30 lb | Residential & commercial roofing underlayment | Affordable, easy to handle, water resistant | Can crack over time, less durable |
| Synthetic Felt | Polypropylene or polyester materials | Varies (lighter than traditional felt) | High-performance roofing projects | More durable, tear-resistant, lightweight | Higher cost, surface slipperier for installation |
| Self-Adhering Felt | Rubberized asphalt with adhesive backing | Varies | Specialty areas requiring water tightness | Superior waterproofing, no nails needed | More expensive, requires skilled installation |
What Is Felt Paper and Why It Matters in Roofing
Felt paper is a waterproofing underlayment traditionally made from a base mat saturated with asphalt or tar. It is installed beneath primary roofing materials such as shingles, metal panels, or tiles. The purpose of roofing felt is to prevent moisture infiltration, protect the wood deck from environmental damage, and add an extra barrier against wind-driven rain. It also facilitates smoother installation of roofing materials and can help improve fire resistance for some roof assemblies.
Types of Felt Paper for Roofing
Organic Asphalt-Saturated Felt
This traditional felt paper uses a cellulose-based mat saturated in asphalt. It is available primarily in 15 lb and 30 lb weights, which indicate density and durability. Organic felt is widely used for residential roofing due to its affordability and ease of handling. However, it tends to absorb water and may degrade faster if exposed to prolonged moisture.
Synthetic Roofing Underlayment
Modern alternatives use polypropylene or polyester mats, offering improved tear resistance, lighter weight, and better moisture management. Synthetic felt papers outperform organic felts in durability and longevity, making them increasingly popular in both residential and commercial roofing applications.
Self-Adhering Roofing Felt
These products combine a waterproof rubberized asphalt layer with an adhesive backing. Designed for critical areas such as roof valleys, eaves, or around skylights, they provide exceptional waterproofing. Though more expensive, self-adhering felt excels in high-risk moisture penetration zones.
Key Factors for Selecting The Best Felt Paper for Your Roof
Weight and Thickness
Roofing felt weight, measured in pounds, influences durability. Most codes require 15 lb or 30 lb felt, with the latter offering better tear resistance and protection. Heavier felts, while thicker, can be more cumbersome to install.
Water Resistance
Look for felts with proven water resistance, especially for regions with heavy rain or snow. Synthetic felts typically repel water better than organic ones and dry faster.
Tear and Puncture Resistance
Durability under mechanical stress is vital during installation and throughout the roof’s life. Synthetic felts provide superior resistance to tearing, minimizing damage risks.
Fire Resistance
Some roofing projects demand Class A fire-rated underlayment. Certain felts meet these higher fire standards, enhancing roof safety.
Compatibility With Roofing Materials
Ensure the felt paper is compatible with your chosen roofing system to avoid chemical reactions or installation issues. Some synthetic felts come with special coatings to adhere better under shingles or metal roofs.
Popular Brands and Industry Recommendations
Several manufacturers offer high-quality roofing felt products that meet ASTM standards and building code requirements. Below are some trusted names and their highlights:
| Brand | Product Line | Type | Key Features | Typical Applications |
|---|---|---|---|---|
| GP (Georgia-Pacific) | Deck-Armor Synthetic Underlayment | Synthetic | Breathable, strong, slip-resistant surface | Residential and commercial roofing |
| Owens Corning | Roofing Felt (Organic) | Organic asphalt-saturated felt | Proven performance, code compliant | Standard residential roofing |
| CertainTeed | Diamond Deck Premium Synthetic Felt | Synthetic | Lightweight, tear resistant, UV stable | Shingle roofs, steep slope applications |
| Grace | Ice & Water Shield | Self-Adhering Felt | Superior waterproofing, extreme weather protection | Valleys, eaves, penetrations |
Comparing Organic vs Synthetic Felt Paper
Differences between organic and synthetic felt paper affect roof protection and installation ease. The following comparison clarifies their trade-offs:
| Feature | Organic Felt | Synthetic Felt |
|---|---|---|
| Material | Cellulose fibers saturated with asphalt | Polypropylene or polyester with waterproof coatings |
| Weight | Heavier, typically 15 or 30 lb | Lighter and thinner for same protection level |
| Water Resistance | Absorbs water, slower to dry | Repels water, promotes faster drying |
| Tear Resistance | Lower, can rip during installation | Higher, resists tearing and punctures |
| Price | Lower cost | Higher upfront cost |
Installation Tips for Roofing Felt Paper
- Start with a clean, dry roof deck: Remove debris and ensure the surface is smooth for proper felt adhesion.
- Overlap edges adequately: Follow manufacturer guidelines, usually 2 to 4 inches horizontally and 6 to 12 inches vertically, to prevent water infiltration.
- Secure felt with nails or cap nails: Avoid using staples which provide less holding power.
- Work safely in all weather conditions: Felt installation in windy or wet weather can be challenging and unsafe.
- Consider professional help for complex roofs: Valleys, skylights, and chimneys require careful detailing.
Cost Considerations and Longevity
The choice of felt paper influences the overall roofing budget and future maintenance needs. Organic roofing felt costs less initially but may require more frequent replacements or repairs due to faster wear. Synthetic felts, while more expensive, can last longer, offering better long-term value. Self-adhering felts are advisable for areas with increased moisture risk despite their premium price.
Environmental and Safety Aspects
New synthetic felts often feature recyclable components and lower volatile organic compound (VOC) emissions. Organic felts use natural fibers but involve petroleum-based asphalt. Fire ratings should also be considered to maximize home safety, particularly in wildfire-prone regions.