Uneven insulation pad

[Elcho]

I have poured a 4 inch vermiculite pad, I leveled it off and have left it for four days.
It seemed to have settled more in some places than others.
Would I be better to put a thin skim of cement/vermiculite across it to level it out or have a thicker leveling medium of fireclay and sand. (how thick can this be?)

[Laurentius]

Re: Uneven insulation pad

Are you placing ceramic board atop that?

[Elcho]

Re: Uneven insulation pad

Nope, was planning on the leveling medium then the fire brick base, costs are starting to get out of control.

[Laurentius]

Re: Uneven insulation pad

I would go with more vcrete, since its not as efficient as ceramic board.