You have some good ideas there. I have pretty much decided to do it
from under the porch, rather than try to move it.

Good luck, I hope it goes well!

Maybe I can make panels with lumber and the metal siding, and attach
them from under the house.

The more you can do out in the open, the less work you'll have on laying
under the house.

There are access doors to get under the house.

I was going to ask you if there was another way under the house. It might
be easier coming at it from that direction than trying to squeeze under the
deck (I don't know if you mentioned how much clearance you had under the
deck).

Yes, the porch is free standing and there is a gap about 3/4" between
the house and the porch

Does the metal crawlspace siding tuck under the house siding somehow? In
other words, what keeps water from going behind the metal siding where it
connects to the house?

because the porch just sits on the ground, so it moves with freeze
and thaw cycles (which is why I would not attach it to the house).

We don't have to worry much about frost heave here in the Pacific
Northwest. Our frostline is technically 12 inches, but it's extremely rare
to have freezing weather long enough to freeze the ground.

Still, I've always built decks and stairs freestanding, mostly to prevent
rot between the deck/stair structure and the house.

Let us know how your project turns out!

Take care,

Anthony Watson
www.mountainsoftware.com
www.watsondiy.com