Step #1.

Your underlayment is installed and nailed, the underlayment type will vary. Typically a 30# organic felt is used this is the most common.

Tile underlayment

Step #2.

Next we install a J-pan metal and nail it to the wall over the top of the underlayment this metal allows water to run off the roof.

J-pan Metal

Step #3.

Next we are going to flash over the top of our J-pan with another metal called Z-bar. 

Z-bar flashing

Step #4.

Now we apply a waterproofing paper over the top of our Z-bar.

Waterproofing paper

Step #5.

Our tile roof wall detail is now complete. Next we will lath and stucco our wall and lay the tile and the roof is correctly installed.

Finished tile wall detail

There are other methods to do wall details as well. This example was used because it’s a common method used in the southwest. Whatever method  you use the principals are all the same. The underlayment always has a flashing over the top.