25mm is standard

its market norm, theres no guideline for it

you can maybe see if theres something in british standards which malaysian design normally refer to, but i doubt there is any guidelines for this

also, you might want to check what is the tolerance level.

i have never seen a 30mm drop. the design probably calls for 25mm. due to the need to form the slope to your floor trap, the contractor probably adjusted the level (or they probably just didnt control the drop height well enough).

drops are normally 1 , 2 , 3 or 4 inches which translate to 25mm 50mm 75mm and 100mm

typical bathroom drops are 1 inch and balcony drops 2 inches. entrance drop 2 / 4 inches

This post has been edited by EdEd: Mar 22 2023, 02:03 PM