All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
We inform you that we do not know any Sunnah particular to living in a new house. What some people do, like slaughtering and putting salt at the entrance of the house is an innovation and a non-Islamic custom. In fact, there is no difference between a new and an old house, the person should say the supplication of entering and that of leaving regardless of the condition of the house. He could also read Sura Al-Baqarah every three days and say Bismillah when entering in or closing the doors.
Allah knows best.