Hello! Just a quick question- I bought a 50 lb bag of insul cast to fill the 2 inch void before laying the firebrick. However- I was a tiny bit bit short on the insul cast…so it is not exactly level with concrete…I’m short by maybe quarter of an inch or less. Can I just make the difference up with the sand or is it super important that it is level with the concrete?
Insulcast insulation is short of being level with the hearth slabs. Is this okay?
You’re good, if by “tiny” you mean a half inch or less. There should be enough there to provide the thermal break you need.
So be happy and keep building!