Corroded aluminum flashing below entry door

Hello and thank you in advance for your expertise and help on this issue.
Our front door has a concrete step leading up to it that connects to the house. There is aluminum flashing that separates the back of the concrete step from the house sheathing, but the top/visible portion of the flashing is corroded and disintegrating, so that the wood sheathing can be seen behind it. Luckily the wood sheathing isn’t rotten at all. There was also normally a block of wood screwed in front of this flashing. There are pictures attached showing the assembly.
How would I go about replacing this flashing properly? I worry that the flashing behind the concrete separating it from the sheathing will also need to be removed, but I won’t be able to do that without demolishing the step. Could I simply install a metal sill pan below the door to cover this space, making sure to caulk all perimeters?
Best,
Andy
Replies
Hi Andy,
As you can see from your step, aluminum does not do well in contact with concrete. One option you could do is to leave the the existing aluminum flashing and layer over it with either some vinyl flashing or flashing tape. I would scrape out the caulk first, put a small bead of sealant down and fill up the hole in the aluminum. Then add either the vinyl flashing or flashing tape. Finish up by caulking the top and sides where concrete step meets the wall/ flashing.
Don't know if it would help at all, but could also seal the concrete. Thinking that the drier the concrete is, less of a reaction with the aluminum. But that is just me guessing.
I'm thinking I'll just put an L-shaped galvanized metal flashing over the old flashing that would extend from the bottom of my door threshold and then extend a few inches over the stoop. A good sealant would adhere this flashing to the old flashing and over the concrete. The old kicker block would then be screwed into the flashing again. Hopefully any water that manages to make it's way down the crack between the concrete stoop and my sheathing will be blocked by the below grade component of the old flashing and will able to dry laterally at the 1-2mm expansion behind the concrete stoop. It's a bandaid fix but properly fixing the issue requires demolishing the back part of the block and completely reflashing the area, which I cannot do myself or without cumbersome expense.