This flashing needs to extend up at least 2 or 3 inches up under the siding above the deck.
Siding to deck flashing.
Fits over leger board and behind siding to protect from water damage.
That should pop the nail head out far enough so you can pry it out.
The irc doesn t provide prescriptive measures for flashing other than the minimum thickness for metal flashing 0 019 in.
My instinct is to replace the deck and eliminate the ledger altogether add posts near the wall and leave a big gap between the end board and new flashing tucked under the siding.
To prevent water from seeping behind the deck s ledger board and rotting the board and the siding the flashing must cover the top of the ledger board and bend over the edge.
Keep in mind the bottom of the upper siding should be at least two inches above the flashing or the decking that s near the house.
Use asphalt paper between metal and pressure treated lumber.
Then slip flashing behind the siding covering the top edge of the ledger.
Galvanized deck ledger flashing fits over deck ledger board and behind siding for protection from water damage.
Pry the siding out near a nail then push the pry bar against the nail as you partially tap the siding back in.
If nails are in the way pull them out.
A simple metal or plastic cap flashing is probably adequate to flash a deck ledger in a dry climate while the 3 layer system described in this video is suitable for high rainfall and damp climates.
Start by making an outline on the siding where you want to position the ledger board.
I would remove the old siding that was behind the existing ledger to about an inch above the deck surface.
If the sidewall is stucco or solid wood like ours and you can t open it to get flashing behind it continue the step flashing to the peak of the roof then cover the step flashing with cap flashing.
Slip the back flashing under the siding at least 3 at the top and the sides.
If the shingle already has flashing on it the kickout flashing has to slip beneath it and you ll have to loosen or remove siding to do this.
You may need to pry out siding first.