Chris, they do most of it in Summer, I applied in 1986ish as a carpenter down there on the biggest build since the sites were established. I was 3 years into my 4-year builder's course at night going 3 nights a week for 4 hours a night and working full time for 6 days a week and really needed a change. I didnt get in. That's either a summer down there or a full year. Winter is flat out deadly outside. Zero building externally in winter, so it's mostly prefab and balls to the wall in summer and depending on where there are 4 bases, or 3 us Ozzies have I don't remember it still bloody cold. Saw a doco a while on the new bit at Scott base the Yanks built at the pole. Its all on jackable stilts so the snow doesn't burry it, and it's all moveable, seems they built it close to a massive crevasse unknowingly and they are hoping the crevasse doest move to close. Absolutely huge wind loads down there.