OK Let's start at the start...Exactly what is a weep screed?

Well here is the corner of a 15 year old home in Las Vegas (not in Sun City).  This particular place was picked because the corner of the home has damaged stucco at the bottom...

So closer in...

And in for a real close up...

There they are...a pair of weep screeds forming the bottom of the walls meeting at this corner.  Note that the metal lath that holds the stucco in place is also visible. 

And her is a sample of weep screed as manufactured...

This is a short segment from the normal 8 or 10 foot length.  The holes in the bottom of the weep screed are about 6 inches apart.

Now let us see what weep screeds do.  For that we need to look at how to stucco a wall.