You may find these commands useful when adjusting file and directory permissions.
To recursively chmod directories only for single user permissions:
find /your/site/root -type d -exec chmod 755 {} \;
To recursively chmod directories only for group users permissions:
find /your/site/root -type d -exec chmod 775 {} \;
To recursively chmod files only for single user permissions:
find /your/site/root -type f -exec chmod 644 {} \;
To recursively chmod files only for group users permissions:
find /your/site/root -type f -exec chmod 664 {} \;