Creases in carpet caused by floor boards moving, i guess??

[allanlaw]

Installed new carpet all over house end of last year, used the best underlay with a decent carpet. Upstairs has creases where the floorboards are but downstairs is ok.

Anybody know why this is happened?

Upstairs is always colder than down!

 

[JohnD]

If you have gappy or loose old floorboards then they will wear out your carpets very quickly in these lines.

Best option is to apply hardboard or ply over the boards (or take up the floor and relay a flat one)