According to the DVD Commentaries and Featurettes, the house in The Grudge (2004) was built completely on a sound stage. It was based almost entirely on the house in Ju-on: The Grudge (2003). It was built like a normal house, the 'house set' had two floors so that cuts did not have to be made when a character was walking upstairs. However, the attic was built separately from the house to allow for more room when filming.
