It depends on the developer, the good ones would deal with these as a standard part of their service. However, most won't.
According the the NHBC the width has to exceed 2mm for it to be defined as a snag.
However, no cracks are acceptable when you take ownership. This is a common problem with stock homes that have been left complete and unsold for a significant period. Normally, when home owners move in the paint and plaster has just about had time to dry let alone crack!
Shrinkage Cracks are a natural process of a new house drying out, and the developer can do nothing to stop that, however, in many cases they will come back and fill them, in any case, if they wont / dont, its hardly a major task getting a bag of filler and filling them yourself, and then touching them up with some paint, or getting a friend or relative to do it for you if your diy skills are anything like mine !!!! :blink:
If your house is render over block work and it is cracking ask whether bed joint reinforcement has been included in the blockwork. Best building practice says it should be and most render manufacturers stipulate it as a pre-requisite. It took 2.5years but eventually our developer admitted that these had not been installed and hence the high volume of cracking in our rendered walls. But don't give up-there is a remedy. The challenge is to get the developer to take proper ownership of the problem and apply the remedy. We are at this point. Will let you know how it ends up.... So stay calm and keep plugging away and don't let them paper over the cracks.
Oh! how refreshing it would be to find a developer with true customer service!! Can you imagine M&S behaving so badly over faulty goods?