The Sidemen House was a luxury mansion in which four of the Sidemen lived. It was dubbed "The Sidemen House", taking the name of the former house. They moved here in mid-2016, after having lived in the former house for around two years. All of them will have departed by early 2019.
KSI, miniminter, Zerkaa, and Vikkstar123 were the four Sidemen who have resided in the house since they first moved in. Various other people (such as Randolph, Lewis Redman, Jordz, etc.) have lived in the house on a temporary basis.
Vik left the house in November 2018 (after nearly five years of living with the other three) to move into his own space. In late 2018, Simon announced he would also be leaving, along with JJ, at some point in the new year. Josh recently announced that he will also be leaving to move in with his girlfriend Freya.
This will therefore be the last "Sidemen House" ever.
The exact location of the house will not be revealed for privacy reasons, however, the house is no longer in an open, suburban area like the old one was. It is situated on a private estate (along with other multi-million pound mansions) with 24-hour security - a factor they undoubtedly considered when choosing a new house. None of the Sidemen have ever filmed a tour of the new house and they haven't even formally acknowledged the fact that they have moved - even to this day. It appears to be a running in-joke that the Sidemen have (pretending they have not moved house), as shown in a 2017 Grand Theft Auto V session. There was a short period of time in early-2016 when they were in the process of moving, so their videos simultaneously showed old and new room locations - regularly switching between the new and old house. Many people grew suspicious when a new and much larger house was seen in the background of the group's videos.
According to Rightmove, the house is around 20 years old - however, other sources suggest it was constructed in 2015. It has a pool complex and sauna, 6 en-suite bedrooms as well as a cinema, gym and beauty salon (which Josh instead uses as the recording area for his Homegrown Podcast series). KSI's bedroom also has its own lift/elevator.
More of the interior of the Sidemen House can be seen in the following videos.