It's a hard time to buy in Wellington at the moment as the market is so strong. Buildings between about 1992 and 2004 may be subject to weathertightness issues, which can be serious, more serious I think that plumbing and electrical issues for houses of that age - although there is a type of plumbing (dux quest) which is inferior so if present will need replacing. I think electrical issues would mainly be found in houses older than 25 years. Although I have been in NZ too long to worry about insulation, there are a lot of ENZ posters who raise that issue repeatedly.