Cedar roof underlayment failure occurs when the protective waterproof layer beneath cedar shakes deteriorates, tears, or loses effectiveness. Since underlayment acts as a secondary barrier, its failure can lead to hidden leaks and structural moisture damage.
Common causes include aging materials, prolonged moisture exposure, poor installation, or damage from fasteners and movement of cedar shakes over time.
When underlayment fails, water can penetrate into roof decking even if the cedar surface appears intact. This often results in hidden rot, mold growth, and insulation damage.
Because damage is concealed beneath cedar shakes, underlayment failure is often difficult to detect without professional inspection.
