Also drainage. Proper stormwater hookup and not just a soakpit etc that will overflow in the first heavy rain.
good point. if you are looking at a house which has an aging soakpit, and you're planning on extending it with another room etc then you're probably looking at another $10K+ to install a council approved soakage device. if you don't upgrade the soakage, then you will get all your building consents rejected. This applies to both houses that are conected to council stormwater, and also houses that have to take care of their own stormwater.