vale, me autorespondo xD simplemente añadiendo -type d
del man:
-type c
         File is of type c:

         b        block (buffered) special

         c        character (unbuffered) special

         d        directory

         p        named pipe (FIFO)

         f        regular file

         l        symbolic link; this is never true if the -L option or the
           -follow  option is in effect, unless the symbolic link is
           broken.  If you want to search for symbolic links when -L
           is in effect, use -xtype.

         s        socket

         D        door (Solaris)