There will be so many cardinals checking in to the Vatican for the conclave next week they’ll have to squeeze in, but at least this time they get their own bedroom and a flushing toilet.

With 133 princes of the Church turning up for the election of Pope Francis’s successor on May 7 — the biggest group of cardinals ever — there is a shortage of space at the Casa Santa Marta, the Vatican residence for visiting prelates which only has about 125 rooms.

One apartment is also out of bounds. Pope Francis chose to live there during his papacy to enjoy the hubbub and his flat was sealed after his death last month as per tradition. It will only reopen with the election of a new pope.

Who could be the next pope?

Two firefighters installing a chimney on a rooftop.

The chimney vital to the announcement of the next pope is installed on the Sistine Chapel

GABRIEL BOUYS/AFP VIA GETTY IMAGES

White smoke billowing from a chimney at night.

The stove has chemicals to produce clear black or white smoke to avoid any confusion

PETER MACDIARMID/GETTY IMAGES

Temporary tenants are being turfed out to make room, but one official said that even that would not be enough. “Staff bedrooms and even the sacristy could be turned into makeshift bedrooms,” said Luciano Gagliano, a Vatican official.

Officials need to get a move on as all cardinals must move in by Wednesday when the conclave begins. On Friday a chimney was installed on the roof of the Sistine Chapel, which will emit smoke during the voting — black for no result, white for a winner.

How long will the conclave last?

Once fuelled by burning ballots, the stove sending up the smoke is now packed with chemicals to produce clear colours after the greyish smoke seen in earlier conclaves confused the crowd in St Peter’s Square.

On Monday, any nurses, Swiss guards, cleaners or drivers likely to meet a voting cardinal during the conclave will be sworn to secrecy on pain of excommunication.

Casa Santa Marta, the Pope's residence in Vatican City.

There is a shortage of space at the Casa Santa Marta, the Vatican residence for visiting prelates which only has about 125 rooms

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Matteo Bruni, the Vatican spokesman, dismissed rumours that Cardinal Pietro Parolin had been taken ill as “not true”, raising the possibility that the papal favourite was a victim of the disinformation which often spreads at conclaves to besmirch rivals.

Amid the growing tension, cardinals can be satisfied they will get their own rooms thanks to Pope John Paul II, who ordered the construction of the Casa Santa Marta in 1978 after a century in which cardinals had to bed down in the 15-room Vatican apartment built by Pope Alexander VI in the late 15th century.

Where do cardinals eat?

Packed in four or six to a room and separated by hastily erected wooden dividers, cardinals struggled to sleep on camp beds. They could enjoy the glorious ceiling frescoes by Perugino but were also forced to share chamber pots.

“We had 111 cardinals in here in 1978 and it was very hard to place them,” said Gagliano as he showed reporters around the apartment.

Entering one room, which featured a fresco of Alexander holding a first meeting with native Americans in the apartment, the official said: “There were beds and a chamber pot here.” Stepping into Alexander’s bedroom, where the ceiling is slathered in gold leaf, Gagliano added: “They even slept in here — every space was taken.”