Last's seasons house was used once again. However, Channel 7 revealed that the next season of the show would move to a brand new house. Compared to last season, the house had very few differences. The "Green Room" was replaced by the new "Cave Room" and the house had a new area specifically for the nomination competitions.
The house was revealed on April 22, 2021. All of the rooms were given a new and revamped style, but ultimately had the same layout.
After the first three housemates entered the house, Big Brother requested that one of them enter the Diary Room. Daniel, who entered it, was given a secret mission to sneak out of the house undetected, with Big Brother providing him with an escape plan. He was also allowed to bring one housemate with him. If he successfully completes the task, he and the housemate that he brings would earn immunity from the first eviction.
On Day 4, Melissa was given a secret mission to hide a lamb figurine in each of the rooms of the house. She was allowed to recruit one housemate to help her. If any of lambs are found, Melissa would fail the secret mission. If she succeeds, the house would earn a lamb roast dinner.
On Day 6, Big Brother placed thousands of balloons in the house. Inside of eighteen of them were golden cinema tickets. If the housemates find a balloon with a ticket, Big Brother would award them a movie night.
On Day 9, the housemates had to participate in "Scary-Oke." Each housemate had to enter the Scary-Oke room one at a time and sing "Walking on Sunshine." Additionally, the housemates had to stick their bodies into a dark box with a creature or an object inside. If all of the housemates succeeded, the house would earn an espresso machine. However, if one housemate failed, the whole house would fail the task.
On Day 11, Big Brother attempted to surprise the housemates by "throwing surprises" at them. Their goal was not to react to these surprises. If the housemates complete the task, they would earn a KFC feast.
On Day 14, the housemates competed in a 24-hour shopping task. Big Brother added a faulty alarm system throughout the house. For the next 24 hours, the housemates had to deactivate the alarms when they rang. If they successfully deactivate the alarm in a certain amount of time, they would earn $10 for their weekly budget.
Big Brother Australia 13 Competition History
On Day 2, the housemates had to climb a 7-meter tower to collect six bags of wooden blocks. They would have to jump off of the tower to retrieve the bags. After collecting all six bags, the housemates would have to vertically stack all seventeen blocks so that they would all be able to balance. The first housemate to do so would become the first nominator of the season.
On Day 5, the housemates, sitting on "wrecking balls," had to swing themselves from larger to smaller wrecking balls. If the housemates fall down, they would be eliminated from the challenge. Once all remaining housemates are on the smallest sized wrecking ball, the winner of the challenge would be the last housemate not to fall down.
On Day 7, the housemates had to hold on to a rope attached to a bar weighing 30% of each housemate's body weight. If the housemates drop the rope, they would be eliminated from the challenge. The last housemate standing would win the challenge.
On Day 10, the housemates competed for the nomination power in teams. Each team, pitted against each other, had to push against a sliding board. If the team successfully pushed the board to the other team's side, the team would earn a point. The first team to earn three points became the co-nominators for the round.
On Day 12, the housemates, competing in pairs, had to walk along a see-saw and place balls on a platform one at a time. The first pair to balance ten balls would win the Nomination Challenge.
Melissa & Tilly
On Day 15, the housemates, competing in pairs, had to stand on a wooden frame opposite of each other. They would have to hold onto an unfixed rope and balance on the frame. If the housemates falls off of the frame, they would be eliminated from the challenge. The last housemates standing on the frame would win the challenge.
Christina & Daniel
On Day 17, the housemates had to lay on a weighted bar worth 15% of the housemates' body weight. The bar was attached to a balloon. If the balloon popped, the housemates would be eliminated from the challenge. The last housemate still laying and with a balloon would win the nomination challenge.
On Day 19, the housemates had to balance on a wooden plank and hold on to a handle attached to a pulley. The pulley would require them to hold their own body weight on the handle. If the housemates drop, they would be eliminated from competition. The last housemate standing would win the nomination challenge.
On Day 22, the housemates had to balance on an unstable pyramid attached to a spring. Throughout the challenge, the housemates had to move up the pyramid onto a smaller surface. If the housemates fall off of the pyramid or touch the pyramid, they would be eliminated from the challenge. The last housemate standing would win the nomination challenge.