The builder is about to put the insulation down on the base concrete of our new porch floor. This will be 150mm (looks like, I haven't measured exactly) Celotex and then whatever goes on top. AIUI, it'll be finished with self-levelling compound and then vinyl.
Now, we're putting the washer/tumble dryer stack in this porch. Is there any likelihood that vibration from the washing machine would, over some number of years, cause the Celotex to crumble, spread sideways a bit, and the floor to sag a bit?