Strip foundations can be 200mm thick and have a house built on them (depending on exact conditions)Someone on this site claims to build entire houses on 200mm concrete.
By that same standard, half inch should be enough...
Just kidding.
It depends what sort of substrate you have and what you're going to use the step for.
chapter 4.4 is nothing to do with strip foundation. link?Strip foundations can be 200mm thick and have a house built on them (depending on exact conditions)
Reference: NHBC Standards, Part 4, Chapter 4.4, Appendix 4.4A, which quotes Approved Document A1/2, Section 2E.
Apologies was looking at an old version. Seems its 4.3 nowchapter 4.4 is nothing to do with strip foundation. link?