floorboard movement

[Tiler Blackpool]

Hi again, just started on a floor in a kitchen, 4m2.just taken up the laminate floor and found the floor boards have some movement. Was going to lay backerboard but not sure im happy with the movement. Cant find where the boards join therefore cant find the joists ANYWHERE to be able to screw then down better. Would 15 mm ply cure this movement or am i kidding myself?? Customers taken a few days off work while im in so dont want want to aggrevate unless necessary. My instinct tells me to tell him to get a joiner in to lay the boards better! Buggars up mine and his schedule though although dont want a qick fix!!

 

[Tiler Blackpool]

Before anyone takes time to answer ive managed to get under the floor to check the joists and find out where they are. Whoever put the boards down only screwed them in at each end of each plank! Thanks anyway

 

[aytiling]

Ditra? Been using it for a long long time and has never failed me yet. I have tiled onto some horrendous T&G floors, even just rolled it over small gaps and never had a problem. Cheap as chips these days and only adds about 5-10mm to the height