Because mine is bare floor, so the ID explain that:
tiles only around 10mm height
HDB bare floor to the door gap is around 40 to 50mm
Hence they need to screed, because dont have ppl who put 30mm of cement before laying tiles. I asked a contractor who happened to be in my company and he say the same thing too. Only if you dont like HDB tiles and want to use your own tiles then no need for screeding.. Now time to ask the ID who say no need screeding why they say so.. Hmmmm
Btw, I heard that HDB only do free cement screeding (up to 40mm) for ppl doing vinyl flooring.. So those who are interested in tiles are on our own liao.. haha