Appears to have turned up overnight middle of the room and is a bubble about a foot and a half across raised over 1cm in the middle.
Underneath is a cement/concrete floor and nothing is on top of it.
How the devil could that happen
Fixing seems to involve heat and something heavy with options on stabbing it and glue.
Underneath is a cement/concrete floor and nothing is on top of it.
How the devil could that happen

Fixing seems to involve heat and something heavy with options on stabbing it and glue.