Should you restore or replace a metal roof, and how is it replaced?
Short answer. If the panels are still sound, a metal roof can often be restored by replacing screws, resealing laps and flashing and recoating the finish, which costs far less than replacement. Replace it when rust has perforated the panels, seams or fasteners can no longer hold, or the roof keeps leaking after repairs; replacement means removing the old panels, repairing the structure and installing new trim, underlayment and panels.
Restore if
- Panels are solid, with only surface rust or chalky paint.
- Leaks trace to screws, laps or flashing rather than holes in the metal.
- The decking or purlins underneath are sound.
Restoration usually means new screws, often a size larger, resealed laps and flashing, rust treatment and a coating system made for metal. A good coating can extend service life, but it cannot fix structural problems or holes.
Replace if
- Rust has eaten through panels, especially at laps and eaves.
- Panels are loose, torn or badly buckled from wind or hail.
- The underlayment has failed and the decking is wet or rotted.
- You want a different system, such as standing seam in place of exposed fasteners.
How a metal roof replacement is done
- Remove the old panels, trim and fasteners.
- Inspect and repair the deck or purlins; many homes convert to a solid deck at this point.
- Install heat-rated underlayment, with leak barrier in valleys and at penetrations.
- Install new eave and valley trim, then the panels, then rake trim.
- Add new flashing, pipe boots, closures and ridge cap.
Switching from metal to architectural shingles is also an option when the slope suits shingles. See metal roofing in Georgia and roof flashing explained.