The practice of installing a metal roof directly over existing asphalt shingles is a roofing technique wherein a new metal roofing system is affixed atop an existing shingle roof, instead of removing the old shingles beforehand. This process aims to create a protective layer, saving time and reducing disposal costs.
This method offers several advantages, including potential cost savings related to labor and disposal fees. It can improve energy efficiency by adding an extra layer of insulation. Furthermore, it minimizes disruption to the building occupants during the roofing process. Historically, roofing directly over existing layers was more commonplace but became less so with stringent building codes. However, with proper planning and adherence to regulations, it can be a viable option for some properties.