Introduction: The placement of roofing felt in relation to the drip edge is a common question for homeowners tackling roof repairs or new installs. Properly layering materials protects against leaks, wind-driven rain, and water infiltration at the eave and fascia. This article explains current best practices, why they matter, and how to apply roofing felt with drip edge to meet building codes and enhance roof longevity. It covers underlayment options, installation steps, and practical tips for U.S. homes.
Understanding Drip Edge And Roofing Felt Roles
Drip edge is a metal or plastic strip installed along the eaves and rakes to guide water away from the fascia and underlying structures. Roofing felt, or underlayment, provides a secondary moisture barrier beneath shingles, protecting the roof deck from leaks caused by wind-driven rain, ice damming, or minor shingle damage. The felt also helps seal around fasteners and offers temporary protection during installation.
In modern roofing, the felt is typically installed over the roof sheathing but under the shingle starter course and field shingles. The drip edge sits at the outer edge of the roof, directly beneath the shingles’ lower edge, allowing water to shed efficiently. The interaction between these components is crucial for an effective moisture barrier and proper drainage.
Code And Manufacturer Guidance
Building codes and manufacturers often specify the correct order of installation. In many U.S. jurisdictions, the drip edge is installed first at the eaves, with the underlayment placed over the roof deck and under the drip edge for eaves protection. Some regions allow the drip edge to be installed over the underlayment, as long as water is directed away from the fascia and the edge remains unobstructed for drainage. For the rake edges, the drip edge is typically set on top of the underlayment to secure the edge and prevent lifting by wind. Always consult local codes and the roofing material manufacturer’s installation instructions to ensure compliance.
Do You Put Felt Under The Drip Edge?
The general rule in most installations is not to place roofing felt beneath the drip edge along the eaves. The drip edge needs to sit directly on the roof deck or on top of the underlayment, depending on the system, so water can flow smoothly into the gutter without being trapped by multiple layers at the edge. Installing felt under the drip edge can create a gap or misalignment that traps moisture or causes flashing to fail. However, in some traditional methods or specific products, a thin layer of underlayment under the drip edge may be used to improve sealing, but this is less common and must follow manufacturer guidance.
For the rake edge (the sloped sides of the roof), the drip edge is typically installed over the underlayment to ensure the edge is well-supported and to help seal the roof against wind-driven rain. Consistency in edge treatment helps prevent wind uplift and blisters in shingles. In all scenarios, the goal is a clean, continuous edge that directs water away from the fascia and into the gutter system.
Practical Installation Scenarios
New Roof With Traditional Felt Underlayment
In a standard asphalt shingle roof, apply the roofing felt (underlayment) over the roof deck. Extend the underlayment to the eaves where the drip edge will be installed. Install the drip edge over the underlayment at the eaves or directly on the decking, depending on product instructions and local code. Then proceed with starter course shingles along the eaves. This sequence ensures that water shed from shingles flows onto the underlayment and into the drip edge and gutter system.
Synthetic Underlayment On Modern Roofs
High-performance synthetic underlayments may differ slightly in sequencing. Some allow the drip edge to be installed after the underlayment, ensuring the drip edge sits atop the underlayment at the eaves. Always follow the product’s installation guide, but the principle remains to avoid trapping moisture under the edge and to maintain a clear drainage path.
reroofing Or Replacing Drip Edge
When replacing a drip edge, ensure the new edge is installed flush with the deck and shingles, with the underlayment properly overlapped to prevent water infiltration. Do not run underlayment under the drip edge if the local code or manufacturer requires it to sit over the underlayment for better drainage. Use sealant or flashing where necessary to close gaps at the fascia line.
Edge Detailing And Sealing Tips
- Overhang Considerations: Maintain a uniform overhang of 1/4 to 1/2 inch beyond the drip edge to guide water into the gutter.
- Flashing Integration: Integrate drip edge flashing with the underlayment to create a continuous water-resistant barrier along the eaves.
- Wind Protection: Properly secure the drip edge to resist wind uplift; use fasteners recommended by the manufacturer and spaced per local code.
- Sealant Use: Apply appropriate sealants at joints or penetrations behind the drip edge to minimize capillary leakage, following product guidance.
Common Mistakes To Avoid
- Installing felt under the drip edge when not recommended by code or manufacturer, which can create drainage issues.
- Leaving gaps or misaligned edges at the rake or eaves, increasing the risk of water intrusion.
- Overstretching or tearing underlayment during installation, leading to vulnerabilities at the eaves.
- Skipping compatibility checks between underlayment and drip edge materials, which can compromise performance.
Maintenance And Inspection
Regular inspections after severe weather help identify edge damage, lifting drip edges, or blistering under the underlayment. Look for exposed fasteners, torn felt, or misaligned drip edges. Address issues promptly to prevent moisture infiltration. If unsure, consult a licensed roofing professional to assess the edge detailing and ensure edge treatments meet current codes and product guidelines.
Frequently Asked Questions
- Can you install drip edge over felt? In many cases yes, at the rake edge, but always verify with the underlayment and drip edge manufacturer. For eaves, installation over underlayment is common when required by code or product specs.
- What if water pools at the drip edge? Recheck the edge alignment, flashing, and gutter installation. A misaligned drip edge can trap water and lead to fascia rot.
- Is synthetic underlayment better than asphalt felt? Synthetic underlayment tends to provide greater resistance to tear and moisture, but both can perform well when installed correctly and used per code and manufacturer guidelines.