Steven Matthews (Wicklow, Green Party) | Oireachtas source

I was just reading it. It applies to compartment floors, which I presume are timber floors in this instance, that require 60 minutes or more of resistance. It reads: "should be constructed of non-combustible materials". Is that compulsory? The word "should" is used, but is that just the way the clause was written at the time and it has travelled through each iteration of the guidance?