I just had engineered wood installed on my ground floor and it went terribly wrong. The floor moves significantly, I would sai almost a centimeter vertically, and vibrates likes crazy.
Here is a video that shows what happens when walking on the floor: http://youtu.be/9OdiJHxPM-I
The builder used a damp proof membrane (Natura Gold), fibrewood, and 6/20 Engineered wood on top of a mixed concrete and timber undefloor. As far as I can tell this is a pretty common setup, except that fibrewood plus natura gold might be a bit more that usually advised. As far as I can tell the appropriate expansion gaps have been left and the wood had been acclimatised for about 2 weeks in the room.
When I pointed out the problem the builder first told me it was normal, then he acknowledged the problem but said it would fix itself in 6 months, then blamed it on the materials and finally suggested screwing up some boards to the underfloor. He basically seems to have no clue, and the fact that he tried to deny the problem and then to blame it on me is not a positive at all.
Do you have any suggestion on how to fix the problem or on how to handle the situation? I’m new to this game and would prefer to avoid ending up in the small claims court.