Permissions to check for upgrade?

I have a 2.6 site that has been running fine for a year. It is on an Apache server. I have FTP access and was wanting to know what permissions in what folders I need to check before doing an upgrade or a full deletion and re-install. I am doing the website from scratch starting next week so i don’t care about losing what I currently have.

I had emailed the owner of the hosting company but he is too busy to address he issue right now.

So what permissions should I confirm I have before attemtping to do an upgrade or total re-isntall after deleting the current web/files/folders?