It's day one of a new room, Master Ensuite. One team feels the Judges are being overly harsh towards them and Keith catches another team cheating. Some Blockheads decide to meddle with the Architects plans and change up their floorplans.

One couple wins five thousand dollars in the Kids Undercover challenge. All teams return to the Block, where two couples are behind the other Blockheads after Keith didn't approve their waterproofing.