We have a total ban policy.

I've taken ASHRAE 62.1's 25mm (1") minimum text size as the Norm for No Smoking Signs requirement (even though the requirement is for "smoking allowed" signs). I've not found anything for the logos.

Do I need no smoking signs at all main entrances to the site boundry only, or do I need additional signage at the building main entrances also?

It's so difficalt to think like the smoking public.