laying karndean directly onto a chipboard floor

[steve_moran38]

I've had a new room built with an 18mm weyroc moisture resistant chipboard floor screwed down. I'm looking to fit a karndean floor and the fittinmg instructions say I need to put down a 6mm ply floor first. Has anyone layed a karndean floor directly onto a chipboard floor without the ply? The floor is very stable with not much movement at all. I can see that sheets of 8x4 ply will provide less joins but it's obviously an extra cost.

 

[flooringman]

The ply isn't there only for stability but to ensure there is no reaction between the chipboard and the adhesive. As a diy job you could risk not using ply but it would invalidate any warranty,
A professional installer would not do the job without ply.

 

[mattysupra]

as flooringman says!