2
cache
templates_c
uploads
CHMOD 777 (or 775 if the webserver user is in the same usergroup as the file owner - or 700 if the webserver uses the same user as the file owner... talk to your host about what your webserver user is) The webserver needs write access to these folders
During installation you need writeaccess to mainfile.php in the root, but after installation make it CHMOD 444