[TRiG_Ireland]

You have to be careful with this. Building sites (translate that into American as "houses under construction") may want to order stuff, but won't yet have eircodes. Indeed, I believe that they're issued only twice a year, so new-built houses may not have them either. So you cannot make it a required field.

[slartibardfast0]

yes, once the 'footings' are in you need to order an eircode straight away, no fibre-to-the-home without any eircode :)