I have read with interest your story. We have had a kitchen extension 3 years ago and about 1 year ago we started to smell a strange smell. We too have Karndean flooring and have sought advice from various professionals without a result. We are wondering whether you have solved your problem and if so what was the result ?? We are thinking of contacting Kardean to see if they can help.......... have you already done this ?? Our smell is like damp plaster, musty, generally unpleasant and like your smell it is worse when the room has been locked up if we are away on hols etc. Any updates would be appreciated - we are desperate.
Yes I did contact Karndean. The tiles are made from recycled plastic and are "inert". No joy there, then...
HOWEVER, the smell did just go away on its own after about 12 weeks! It came back at about the same time the next year, but this time faded away after about 4 days. Still no idea what caused it, but it went away on its own.
We just hope it has found somewhere more welcoming to live...
Let me now how yours goes!
Where do you live? We are in Buckinghamshire, UK. I wonder if there are any geological or other commonalities?