Roofing felt, also known as tar paper, is a critical component in residential and commercial roofing systems. It serves multiple purposes that help protect buildings from weather elements, ensure longevity, and provide a secure base for roof shingles or other coverings. Understanding the purpose of roofing felt is vital for homeowners, builders, and contractors aiming to improve roof durability and performance.
| Function | Description |
|---|---|
| Water Resistance | Acts as a secondary barrier against water intrusion under roofing materials. |
| Protection | Protects the roof deck from damage caused by weather during installation or roof failure. |
| Improved Shingle Performance | Provides a smooth surface to improve shingle adhesion and durability. |
| Vapor Barrier | Controls moisture vapor to reduce condensation inside the roof structure. |
| Fire Resistance | Some types provide additional fire retardant properties enhancing safety. |
What Is Roofing Felt?
Roofing felt is a type of underlayment traditionally made from organic or fiberglass mats saturated with asphalt. It is commonly available in rolls and installed underneath shingles. Roofing felt serves as a protective, water-resistant layer between the roof deck and the outer roofing material, playing a key role in maintaining roof integrity.
Primary Functions Of Roofing Felt
Water Resistance And Leak Prevention
One of the primary purposes of roofing felt is to act as a waterproof barrier. If water penetrates the shingles due to damage or heavy rain, the felt reduces the risk of leaks by preventing water from reaching the wooden roof deck. This secondary barrier helps avert costly interior damage.
Protection During Installation
Roof installation or repairs can expose the wooden roof deck to weather elements. Roofing felt protects the deck from rain, wind, and debris during this vulnerable period. This temporary shield helps maintain the deck’s integrity until the outer roofing is fully installed.
Enhanced Shingle Performance
The smooth, stable surface provided by roofing felt facilitates proper shingle attachment. It also reduces friction and wear between the roof deck and shingles, prolonging the lifespan of the roof covering. Additionally, certain types of roofing felt improve the adhesion and alignment of shingles.
Vapor Barrier And Condensation Control
Roofing felt helps regulate moisture vapor movement within the roofing system. This control reduces the risk of condensation buildup, which can cause mold, rot, and structural damage over time. Proper moisture management is critical in maintaining a healthy roof environment, especially in humid climates.
Fire Resistance Benefits
Many modern roofing felts are manufactured with fire-resistant properties. This feature adds a layer of safety by slowing down the spread of flames during a fire, providing extra protection to both the roof and occupants of the building.
Types Of Roofing Felt And Their Uses
| Type | Material Composition | Thickness/Weight | Common Uses |
|---|---|---|---|
| Organic Roofing Felt | Cellulose fibers saturated with asphalt | 15 lb and 30 lb varieties | Used mostly in traditional roofing with wood decking, effective in water resistance but less fire resistant |
| Fiberglass Roofing Felt | Glass fiber mat saturated with asphalt | 30 lb and 40 lb varieties | More durable and fire-resistant, commonly used with asphalt shingles |
| Self-Adhering Felt | Rubberized asphalt with adhesive backing | Varies | Used for added waterproofing, especially in valleys and roof edges |
Benefits Of Installing Roofing Felt
- Extended Roof Life: By adding a waterproof and protective layer, roofing felt helps roofing materials last longer.
- Cost-Effective Protection: It offers an affordable solution to reduce damage risks, preventing expensive repairs.
- Improved Roofing System Durability: Enhances overall durability and resilience against weather elements.
- Enhanced Weatherproofing: Acts as a barrier against rain, snow, ice, and wind-driven moisture.
- Fire Safety: Certain felts improve fire resistance, offering increased protection.
Common Installation Practices For Roofing Felt
Installing roofing felt appropriately is crucial for maximizing its effectiveness. It is typically rolled out horizontally, starting at the roof’s lowest edge, and secured with nails or staples. Overlapping each row ensures a water-tight seal. Special attention is given to roof valleys, edges, and around penetrations like chimneys and vents.
Important Installation Tips:
- Ensure the roof deck is dry and clean before installation.
- Overlap layers by at least 2-4 inches.
- Use appropriate fasteners to prevent wind uplift.
- Consider synthetic roofing underlayment for enhanced performance in certain climates.
- Apply self-adhering felt in vulnerable areas to boost waterproofing.
Alternatives To Traditional Roofing Felt
While roofing felt remains popular, synthetic underlayments have gained traction. These newer materials provide superior durability, lighter weight, and better water resistance. They also often include UV protection, making them suitable for longer exposure during roof installation. However, roofing felt continues to be favored for its affordability and proven performance in many applications.
Factors To Consider When Choosing Roofing Felt
| Factor | Consideration |
|---|---|
| Climate | Humid or rainy climates benefit from more water-resistant materials. |
| Roof Type | Steeper roofs may favor lightweight synthetic underlayments. |
| Budget | Traditional felt is cost-effective; synthetic options can be pricier but offer more features. |
| Building Codes | Some local codes require specific fire ratings or materials. |
| Longevity | Heavier felt offers longer protection; synthetic may last longer under UV exposure. |
Maintaining Roofing Felt For Prolonged Roof Performance
Although roofing felt is typically concealed under roofing materials, proper roof maintenance indirectly protects and supports its lifespan. Regular inspections for leaks, damaged shingles, and proper attic ventilation reduce moisture buildup that can deteriorate the felt. Prompt repair of any roof damage protects all underlying layers, including the felt.