Flashing Against Existing Panel Siding

Above the roof sheathing.
Flashing against existing panel siding. Or pull the nails out of the closest layer of siding and slip the flashing up under it and hopefully under the moisture barrier. It is always recommended to install step flashing behind stucco dryvit wood panel lap siding vinyl siding cedar shingle siding etc. Begin at either end of the wall and set the level middle section of the z flashing onto the top edge of the siding panel with the wider flange upward and against the wall framing. Slip in the flashing.
However in most instances step flashing should be installed behind siding. In certain instances flashing may need to be installed on the exterior of siding. Wall or siding connection to foundation top porch floors slabs. Cover with cap flashing.
Flush the end of the flashing length with the wall corner and secure the flashing to the framing with an 8d nail at each wall stud. Using a metal j flashing between these types of transitions provides a barrier between siding and transitions that protects against water intrusion. Imo and that is all it is. Building wall or siding flashing details at horizontal surfaces.
Nail it to the sidewall or glue it if nailing isn t possible. Since newer installation guidelines do not recommend caulking this joint but instead recommend leaving a small gap and flashing behind the ends of the siding i think it is more prudent to add flashings when it is possible to do so. On a wall to be covered with wood cement board vinyl or metal. The only way is to cut a groove in the siding and flash the roof wall intersection.
Install the flashing before you finish the top of the brick wall as the flashing must go behind the siding as well as behind and under the top row of bricks that angle outward to cover the top. But the j cap also creates a consistent line. Lift the bottom shingle and slip in the kickout flashing. Flashing is a strip of metal usually aluminum about 8 inches long and bent at 90 degrees with each side at least 5 inches wide.
Flexible flashing tape seals the eave to the wall. Once the flexible flashing is set i apply a piece of housewrap along the wall where the fascia meets it. This aritcle describes the cause repair and prevention of leaks rot damage at a wood framed wall that was not properly flashed and sealed at the wall bottom. Flashing materials choices installation details specifications.
I use a wide piece of flexible flashing tape to protect the area between the subfascia and the wall.