bouncy kingspan and screeding

[marsaday]

i am doing UFH in the kitchen and have got to the stage of laying the visquene and 75mm kingspan sheets.

the boards are now taped up, but i am worried they are too bouncy and a screed of 65-75mm will not be enough to weight them into the cement floor underneath.

has anyone got any advice. will this quantity of screed weight the boards firmly? i have done a concrete screed in the past and had the same problem, but i was laying 100mm and this weighted down the boards no problem.

 

[^woody^]

If the boards are on a firm and level base and also not wedged in tightly between the walls, then they should not bounce at all

 

[marsaday]

i laid out the boards on my prepared screed base and they didn't move much - just a little bit. then i put down the visquene and the boards move around a lot more. what am i doing wrong?

have you got to smooth out the membrane to be totally straight and flat?