A group of students were left "shaken up" after the ceiling fell through into the living room of their rented house in Cardiff.
The seven women live together at Ruthin Gardens in the Cathays area of the city.
They said they noticed the bathroom floor directly above the lounge, which also had a crack in it, becoming "spongey and damp" before the ceiling caved in on October 29.
They found the experience so distressing that one of the them has gone home to her parents, saying the house is not safe despite paying nearly £400 a month in rent.
The third year students at Cardiff University claim that when they complained to CPS Homes, who are responsible for overseeing the management and maintenance of the house, workers who came to assess the danger posed by the ceiling covered the crack in the bathroom with plywood.
CPS Homes apologised to the students and said initial clean up work "was carried out within four hours of being reported".
A spokesperson for the letting agency said it has been working "extensively" to resolve the problem and is continuing to liaise with the landlord to secure the tenants "the compensation they deserve".
One of the women said: “When we arrived we saw these cracks and we thought ‘this is definitely going to fall through’. It was an accident waiting to happen.
"The ceiling was drooping. It’s been drooping since we moved in with evidence of water being held in the ceiling".
They continued: “We told them that the floor in the bathroom was not safe, and they responded by putting some plywood over it. But this has been going on for years and so surely it was all rotten and was just a matter of time until this would happen.
"We think because this was a big job which would have cost a lot of money they decided they didn’t want to sort the issue properly."
Prior to the ceiling collapsing, the women decided it was no longer safe to use that bathroom and shared one shower and toilet between them.
Another of the students said: “Besides the issue with the hole in the ceiling, there is mould on the walls throughout the house, the boiler is broken, it stinks of damp throughout, the bedsheets are cold and damp, the shower is cold, the toilet doesn’t flush properly."
They added: “We are really shaken up. This is no way for a group of students to live. We have priorities with our course and we’ve spent two whole days not being able to use the facilities we have paid for.”
A spokeswoman for CPS Homes said: “We were sorry to learn of this report when the tenants brought it to our attention.
"The landlord’s own contractor recently attended and performed work that we were told would resolve a leak in the bathroom above the kitchen, though it now appears that the issue was misdiagnosed or the repair carried out wasn’t sufficient, causing plasterboard to come down.
“We extend our apologies to the tenants for this and, since being made aware of the issue on Saturday, have worked extensively with our landlord client, their contractor and the tenants to have everything resolved as quickly as possible.
"Clean up work and initial making good was carried out within four hours of being reported, with full repairs commencing on the next working day.
"We are continuing to liaise with the landlord on the tenants’ behalf to secure them the compensation they deserve for the inconvenience caused.”