To glue or not to glue (XPS)

[DynamicC]

Hi everyone, 

I am looking at buy thing kit to install in my open plan downstairs area.

https://underfloorheating1.co.uk/product/premium-xps-lowprofile-kit-50m2

I noticed in the install guide that the XPS panels need to be bonded to the subfloor with a flooring adhesive. I have seen other brands selling similar insulation panels that say this is not required when using using Laminate or Vinyl interlocking flooring on top. 

What are your thoughts on this, could I get away with out using a glue?

Many thanks 

[SteamyTea]

The way extrusion modifies the polymers means it want to bend naturally.

As a rule when I worked in the plastics industry, we avoided anything extruded. Except bagging material obviously.

 

So stick it down.