 Re: Fireclay in the hearth floor?
Welcome, We have some alan scott style bread oven builders here. The fireclay layer under the hearth floor mostly dates from the time when builders used vermiculite concrete for their under-floor insulation, and were left with a rough surface that needed to be leveled before laying down the floor. This is less important if you use modern refractory insulation blocks under the floor which leave a smooth surface. I just laid my bricks down on top of my insblock19 insulation.
Re-reading your question, it's about fireclay in the support slab. The answer is no - you want regular portland-sand-gravel concrete for maximum strength. This slab holds up a lot of weight, and under the insulation it won't get hot anyway, just warm to the touch. |