Kingston
Canadian Royalty
I was wrong. According to the floor plan on World of BB there was an airlock in the original BBUS house.Although of course BBUS in the first series went with things like "Red Room" and "Banishment" instead of the Diary Room and Eviction. Not sure if that was them doing their own thing or came out of the translation of the Dutch/German versions.
BBUK pretty much set the mould for most future series - they were the first to have a weekly cycle of evictions compared to the two week cycle the European versions had in the early years, somethng most subsequent versions picked up. From documentaries at the time it was something they really had to fight the creators on though.
And back to the "airlock" conversatiion. I'm sure BBUS did add a short corridor between the diary room and main house in the original house too, but it wasn't there in the first series, as seen here in the first ever nominations.
It also wasn't located right next to the lounge until BB5 - originally it was further down by the bedrooms, so away from the main living area. TBH I thought Australia was the same for BB1 and BB2 anyway. BBUK just had sound proof doors until BB8, some of which proved to be more soundproofed than others.
Paul Romer, co-creator of the original series, served as the Executive Producer for BB1. I’ll assume things like the DR being called the Red Room and Evictions being called Banishments were translated from the original. In fact BB1 for the most part was just a direct translation from the original Dutch show.