Galvalume is sheet steel coated with an alloy of aluminum and zinc. It is more corrosion resistant than galvanized steel but it doesnÂt self-protect scratches or cut edges nearly as well and it is also more susceptible to staining from corrosion at tight bends (tension bend staining) so it is used most commonly in simple profiles like standing seam roofing. Galvalume steel is very shiny so although it is sometimes installed unpainted, it is usually painted on a house. It must be cut with a shearing action rather than saw-cut. If the porch roof slopes are low you might consider running the metal roofing up the main roof a foot or two in order to protect that intersection. There are other precautions depending on your climate.

We are looking for a replacement for CertainTeed Independence Driftwood too, what did you end up using? My daughter's roof in Louisiana was destroyed in Hurricane Laura...literally "Gone with the Wind"! We have not found a replacement yet and need to make a decision immediately because Hurricane season is upon us again! Thanks in advance.

Also wanted to ask if cellulose or fiberglass insulation would be a better choice for the attic. I live in a cold climate (Michigan) if that influences the type of insulation.

It appears to be where a piece of a shingle was glued down with not enough roofer's mastic to camouflage the flashing. It's cosmetic. If you can't reuse the piece you found on the ground, you might find a scrap of a similar color to use. I wouldn't buy a whole bundle.