Small roll roofing felt, commonly known as tar paper or asphalt felt, is a flexible underlayment used beneath shingles and other roofing materials. Its primary role is to provide a moisture barrier, protect the roof deck during installation, and help reduce wind-driven leaks. For homeowners and contractors, understanding the options, installation methods, and best practices for small roll roofing felt can improve roof longevity and performance while controlling costs.
What Is Small Roll Roofing Felt
Small roll roofing felt is a sheet of asphalt-saturated felt or fiberglass-reinforced material sold in compact rolls. It is designed to be laid across roof decks to act as a secondary barrier against moisture and to improve fire resistance and insulation efficiency. Traditionally used as an underlayment beneath asphalt shingles, it also serves as a temporary roof cover during construction and weather events. The most common varieties are 15-pound and 30-pound felt, measured per 100 square feet, with modern fiberglass varieties offering improved tear resistance.
Types And Grades
There are multiple formulations to meet different climate and building code requirements. Asphalt-saturated felt is the traditional choice, offering cost efficiency and broad compatibility. Fiberglass-reinforced felt increases tear strength and odor resistance, making it suitable for steeper pitches and challenging weather windows. Polymer-modified or high-performance underlayments provide enhanced waterproofing and UV resistance for longer exposure times during construction.
- 15-pound felt: Lightweight, economical, common for many residential roofs.
- 30-pound felt: Heavier, more durable, better for windy or high-snow areas.
- Fiberglass-reinforced: Higher tear resistance and puncture resistance.
- All-weather or synthetic underlayments: Modern alternatives with higher water protection and faster installation.
Applications And Best Practices
Small roll roofing felt is typically installed over a clean, dry roof deck starting from the eaves and working toward the ridge. It should be overlapped according to the product guidelines—often 2 inches for shingle applications and 6 inches for certain metal roofs or long runs. Nails or staples used to secure the felt must be driven straight and set to avoid tearing the material. In areas with heavy rainfall or snow, additional sealing measures at the eaves and rake lines improve performance. Always follow local building codes and manufacturer recommendations for overlap width, nailing pattern, and wind uplift considerations.
Choosing The Right Size And Material
Selection depends on climate, roof pitch, and the roofing system. For low-slope roofs, a high-grade underlayment with superior water resistance may be warranted. For higher wind regions, fiberglass-reinforced or synthetic underlayments offer superior durability. Consider the following when choosing:
- Roof pitch: Steeper pitches benefit from tear-resistant underlayments.
- Climate: Regions with frequent heavy rain or snow favor higher-grade products with improved moisture control.
- Code requirements: Some jurisdictions specify minimum underlayment standards; confirm with local codes.
- Installation window: Quick installation products reduce exposure time if construction is interrupted by weather.
Installation Tips
Proper installation is essential for maximum performance. Start at the eave line, align the roll, and unroll evenly to avoid wrinkles. Use corrosion-resistant nails or staples at prescribed spacing, typically every 12 to 18 inches along the edges and around penetrations. For protrusions such as chimneys and vent pipes, cut the felt precisely and seal with compatible flashing. Maintain straight, uniform overlaps and avoid walking on exposed felt to prevent tearing. If weather changes are imminent, place temporary coverings to protect the roof deck until shingles are installed.
Storage, Handling, And Handling Precautions
Store rolls on a dry, shaded surface off the ground to prevent moisture absorption. Keep rolls flat and avoid placing heavy objects on top that could crease or deform the material. When transporting, secure rolls to prevent shifting and accumulate sharp objects that could puncture the surface. Wear gloves to reduce skin irritation from asphalt materials and ensure proper ventilation during cutting or seam sealing tasks. Dispose of defective or damaged rolls according to local waste guidelines.
Maintenance And Inspection
A well-installed small roll roofing felt requires periodic inspection, particularly after strong winds, hail, or severe storms. Look for lifted edges, tears, or exposed deck. If water infiltration is suspected, address the area promptly to reduce the risk of wood rot or mold. While felt itself can degrade over time, its main role is as a protective barrier during the roofing installation period; in most residential roofs, the shingle layer provides the primary long-term waterproofing, but underlayment continues to support moisture management and wind uplift resistance.
Safety And Environmental Considerations
Handle rolls with care to avoid slips or accidental cuts. Use eye protection when cutting and ensure adequate ventilation when applying adhesives or flashing components. Environmentally, asphalt-based products contain petroleum-derived components; consider recycled-content or low-VOC options where available, and follow disposal guidelines for any tar-based residues. For renovations or retrofits, verify compatibility with existing roofing materials to prevent chemical reactions or moisture entrapment.