Is it ok to put refactoring morda under your firebricks inside the oven ? If not what’s recommended?
Welcome to the BrickWood forum!
BrickWood does not recommend installing refractory mortar under the hearth firebrick.
The design is like a layer cake. The layers (from bottom to top) are:
- The base concrete
- An insulating layer
- A leveling sand layer
- A floating refractory layer of firebrick
The insulating layer is Portland cement mixed with Vermiculite—lightweight and inexpensive. An equivalent layer of refractory mortar would be very expensive without adding significant insulation.
Are you currently building an oven, or making plans to do so? Look forward to hearing from you here as you proceed!