No You Do Not Need To Etch It But You Do Need To Seal It. If Water Swets Through It Will Ruin All Of You Hard Work And You Will Have To Tear It Up And Start Over. Go To Lowes For Pros.com And They Should Have The Basics On There
TNHunter is rght, Should seal the floor first in case of water seapage. Wish I could remember what I've used in the past. Like already mentioned, if it floods nothing is going to help it though.