Should Old Roofing Felt Be Removed for a Modern Roof Update

Old roofing felt, also known as underlayment, plays a key role in protecting the roof deck from moisture. Whether to remove it during a roof upgrade depends on its condition, the type of roof, and the chosen replacement underlayment. This guide explains when to remove old felt, how to assess its state, safety steps, and best practices for installation of a new underlayment. Understanding these factors helps homeowners make an informed decision that supports long-term roofing performance and warranty compliance.

Reasons To Remove Old Roofing Felt

Removing an aging underlayment can prevent hidden moisture problems and mold growth that may compromise the roof deck. If the felt is deteriorating, curling, lifting, or extensively water-stained, removal is often recommended. Old felt may also be incompatible with newer roofing systems or synthetic underlayments, which offer better moisture resistance and durability. Additionally, removing the old layer provides a clean surface for the new underlayment, improving adhesion and performance.

Assessing The Condition Of The Existing Felt

Inspect the current roof from the attic and, if safe, from the exterior. Look for soft spots in the decking, mold, or signs of moisture intrusion. Common conditions include:

• Curling or cracking of the felt surface
• Water staining or staining on the decking
• Delamination where layers separate
• Heavy wear near seams or a brittle, crumbly feel

If moisture damage or extensive deterioration is present, removal is typically warranted. For minor wear on a uniformly installed felt, some contractors may opt to overlay with a new underlayment, depending on the roof type and warranty requirements.

When It Might Be Better To Leave It In Place

In some cases, leaving the old felt can be appropriate. If the felt is still intact, dry, and securely attached, and the roof is being reroofed with a compatible underlayment, some installers will overlay a new layer rather than remove the old one. This approach can save labor time and minimize waste, but it must align with manufacturer guidelines and local building codes. Synthetic underlayments often perform well when installed over existing felt, offering improved moisture resistance and a flatter surface for the new shingles.

Safety Precautions And Preparation

Roofer safety is essential when removing old felt. Before work begins, ensure a stable ladder setup, fall protection, and proper PPE. Clear the work area of debris and protect landscaping and property. If asbestos-containing materials are suspected in older homes, professional assessment and abatement may be required. Weather conditions matter; avoid removing under windy or wet conditions to prevent slips and damage. Gather the right tools: pry bars, utility knife, roofing nails, and a sturdy waste receptacle for disposal.

Removal Process

The removal process should be performed methodically to protect the roof deck and ensure a clean surface for the new underlayment:

1. Access and safety check: Verify roof accessibility and secure fall protection. Inspect for any structural issues before starting.
2. Edge removal: Start at the eave edges and work upward. Gently lift the felt to avoid tearing the roof deck.
3. Deck inspection: As felt comes off, inspect the plywood or sheathing for rot, mold, or nail pops. Replace damaged sections as needed.
4. Disposal and cleanup: Remove all old felt, nails, and debris. A magnet can help collect stray nails to prevent future damage or injury.
5. Surface preparation: Ensure the deck is clean, dry, and ready for the new underlayment installation.

If the deck shows extensive damage, consult a professional for repairs before proceeding with underlayment installation. Improper removal can expose roof edges or create additional vulnerabilities that compromise the new roof system.

What To Install As Replacement

Choosing the right underlayment is crucial for long-term performance. Options include:

• Asphalt-saturated felt (traditional) as a cost-effective, familiar option, though less common on modern roofs.
• Synthetic underlayment made from polymers, offering superior tear resistance, UV stability, and moisture protection.
• Ice and water shield at eaves and roof penetrations to guard against ice dams and roof leaks.
• R- or ISO-based underlayment for enhanced insulation and redundancy in energy-efficient roof assemblies.

Install underlayment per manufacturer instructions and local building codes. Proper exposure, seam sealing, and fastening are critical to prevent wind-driven lifting and moisture intrusion. If a new roofing system is installed, ensure the underlayment choice aligns with the roof type, climate, and warranty requirements.

Weather, Climate, And Warranty Considerations

Climate influences underlayment selection. Regions with heavy rainfall, snow, or freeze-thaw cycles benefit from a robust underlayment and potential ice-damming strategies. Warranty terms may require that the old felt be removed or that a specific type of underlayment be used. Always verify with the roofing contractor and check manufacturer installation guides to avoid voiding warranties and to ensure code compliance.

Cost And Time Implications

Removing old felt adds labor and disposal costs but can prevent costly deck repairs later. The overall project timeline may extend by a day or more, depending on deck condition and the underlayment chosen. Budget for additional materials, such as new nails and fasteners, and potential repairs to damaged decking. A properly staged removal and installation can reduce callbacks and ensure a longer-lasting roof.

Common Pitfalls To Avoid

• Overlooking deck damage beneath old felt, leading to premature roof failure.
• Using incompatible underlayment with existing roofing materials or warranty requirements.
• Inadequate ventilation that traps moisture and promotes mold growth in the attic and roof structure.
• Failed seams and improper fastening that allow wind uplift or moisture intrusion.

Summary Of Key Considerations

Old roofing felt should be removed when it is deteriorated, waterlogged, or incompatible with the new roofing system. A thorough deck inspection, proper safety measures, and alignment with manufacturer guidance are essential for a successful upgrade. When in doubt, consult a licensed roofing contractor to determine whether removal, replacement underlayment, or overlay is the best approach for a durable, weather-resistant roof.