The foundations are believed to have been washed away by flood waters
Engineers are continuing to examine a block of homes, believed to have been weakened by Cumbria's recent floods, which are at risk of collapsing.
Four maisonettes were evacuated on Thursday night when a wall crumbled into the River Greta at Keswick.
Builder Mike Hodson said the foundations had been "washed out".
The residents are living in temporary accommodation and police have cordoned off the area until structural assessments have been completed.
Mr Hodson, who examined the damage on Friday, said there was a "serious danger" of more collapses.
He also said the affected building would have to be demolished as it would not be safe to attempt repairs.
Emily Lane, who lives in a nearby house, said those who had been evacuated were very upset.
The towns of Keswick and Cockermouth were among those worst affected by the unprecedented downpour three weeks ago which saw more than 1,300 properties flooded across the county.
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