The full server path to the web-server root for Upipe hosting accounts is:
/usr/local/psa/home/vhosts/yourdomain.com/httpdocs/
The full server path to the web-server root for our other Plesk-based hosting accounts (MDH, OHP, WebPro) is:
/home/httpd/vhosts/yourdomain.com/httpdocs/
Replace "yourdomain.com" with the actual name of your site.