Short answer: metal can sometimes be installed over existing shingles in Sacramento, but full tear-off is often the better path so decking, underlayment, and ventilation can be addressed before panels go on.
When Overlay May Work
- Single layer of shingles in fair condition
- Solid decking without soft or rotted sections
- Adequate structure for combined layer weight
- Flashing and edge details that can be rebuilt correctly at transitions
When Full Removal Is the Better Call
PRC 13 typically recommends full removal when attic inspection reveals moisture staining, soft plywood, failed underlayment, or when multiple shingle layers already exist. Tear-off adds labor upfront but prevents hidden problems from shortening metal roof life.
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