Windows at high-rise apartments in Cardiff Bay are "spontaneously combusting", housing bosses have told residents.
The 18-storey building at Ferry Court, Prospect Place, has seen a number of windows affected in recent weeks, with one falling from the top floor.
The company which runs the development, Warwick Estates, has since closed part of a walkway to "protect people from falling glass" from Pendeen House - where flats have sold from between £136,000 to £320,000.
An email from Warwick Estates was shared by Grangetown councillor Ash Lister in response to the partial closure of the Cardiff Bay Trail.
The email, sent on October 4, said: "Unfortunately, we have had to close a section of the walkway around Prospect Place due to glazed units to the 18-storey building spontaneously combusting.
"We had an incident two weeks ago, whereby a glazed unit fell out of the 18-storey window and on inspection another glazed unit on the eight floors has also cracked, which was made safe last week.
"We have another glazed unit on the 11th floor which seems that will go the same way as the above.
"As you can appreciate our main concern is the health and safety of residents and members of the public that use the walkway and as such we have taken the decision to close the area of the boardwalk to protect people from falling glass."
The email added developers Bellway, which built the apartment, is "aware of the situation" and will carry out work on the windows.
Warwick Estates also told residents the walkway will remain closed until the work takes place at the apartment complex.
On Friday the walkway remained blocked off by metal fencing.
A Bellway Homes spokeswoman said: "We are working closely with residents and the management company to remedy this situation. In the meantime, we have put safety measures in place and have set up a dedicated procedure to allow for us to quickly respond to any defects."
A recent freedom of information request also found that non-compliant aluminium composite material (ACM) cladding - which is thought to have contributed to the Grenfell disaster - was found on 15 high rise residential buildings in Wales, including buildings in prospect place.
Seven buildings at the Prospect Place were affected. It is not known if Pendeen House was one of the affected.
ACM cladding was found on 12 privately owned buildings and three in the social housing sector.
Warwick Estates has been asked to comment.
