The script for the film was written by Laura Lau, and based on the Uruguayan film La casa muda (2010). According to Lau, she saw the original film twice and wrote the script for the remake based on the viewings rather than adapting it from paper. The script ultimately came out to around fifty-five to sixty pages,Kentis & Lau 2012 (0:20:27) which left the filmmakers concerned as to whether or not the timing would translate during filming: "We wondered whether it would time out properly, because there are no cuts," said Lau. "There’s no way to fix anything in post, it has to pace perfectly when you shoot it. So I think that was a huge challenge in terms of writing the script." Upon acquiring the house used for filming, Lau re-wrote the script in order for it to be compatible with the restrictions and characteristics of the house.Kentis & Lau 2012 (0:21:04)
