07/02/2025
When undertaking a roof replacement, the removal of existing felt paper (underlayment) is a critical step that is often overlooked. The presence of old underlayment can lead to significant issues, particularly concerning water damage to the underlying decking.
1. Mitigation of Moisture Intrusion: Old felt paper can trap moisture, creating an environment conducive to decay. Condensation or minor leaks can accumulate between the layers, leading to rot, mold, and eventual structural damage to the wood decking. Removing the old layer allows for a clean, dry surface, minimizing the risk of moisture-related problems.
2. Enhanced Leak Detection: Multiple layers of underlayment obscure the source of leaks. Water can migrate between layers, complicating the diagnostic process and leading to inaccurate repairs. Removing the old layer provides a clear view of the decking, facilitating accurate leak identification and effective remediation.
3. Ensuring a Uniform Surface: Aged felt paper often exhibits irregularities, such as wrinkles or wear, which can compromise the integrity of the new roofing system. Installing new materials over an uneven surface can affect shingle adhesion and alignment, reducing the lifespan and performance of the roof.
4. Weight Management: Multiple layers of underlayment increase the overall load on the roof structure. This added weight can strain the framing, particularly during periods of heavy precipitation. Removing the old layer helps maintain a manageable weight, reducing stress on the structural components.
5. Facilitation of Thorough Inspection: Removal of the old underlayment allows for a comprehensive inspection of the decking. This enables the identification of existing damage, such as rot, soft spots, or pest infestations, which can then be addressed before the new roof is installed.
6. Compliance with Warranty Requirements: Many roofing material manufacturers stipulate the removal of old underlayment as a condition for warranty validation. This requirement ensures that the new materials are installed on a sound substrate, maximizing their performance and longevity.
