Homebrew Castable 21" Kent (UK)

[UtahBeehiver]

You will need a fire brick floor. Cast floors just do not work due to expansion and contraction of the material. AR glass fibres are not a substitute for melt extract needles.

[bamforp]

Hello all - I am a first time poster, medium term lurker planning a 21" homebrew castable oven for my son in Kent (UK). Space and budget are tight so a 21" along the lines of David S's ovens looks like a good fit for us. I think we are broadly following convention (concrete slab, brick base, 100 mm Thermalite blocks resting on lintels, homebrew dome cast over sand followed by second cast for gallery, 50 mm ceramic blanket, 15mm render and probably waterproofed with white tanking slurry). The two areas where we might diverge a little is that I am planning to use AR glass fibres in the homebrew rather than stainless needles (but will include the PP fibres) and we are also planning to use a cast 50 mm base (probably cast as two halves) as our cooking floor rather than firebricks. Are there any reasons why a cast cooking floor is a bad idea beyond aesthetics and the possibility to replace firebricks? Also, any thoughts on AR glass fibres?

Regards

Peter