Hi from Canberra, Australia

[Dogzbum]

G'day,
I'm planning to build my wfo soon and will be drawing on the collective brains trust here. Brick stand is finished, slab on top will be next.
Cheers !
Dogzbum

[david s]

Do yourself a favour and cast about three 12/“ holes near the centre of the slab. These will act as both drain holes should yo get water intrusion there, but also provide a pathway for steam to escape during firing.
I also like to mound the slab up slightly so water is discouraged from entering under the cooking floor.

[Dogzbum]

Thanks david s, So the 1/2" holes will be under the insulation and oven floor bricks?

[david s]

TYes that’s correct some wall or floor tiles with 1 cm gaps between them, placed between the supporting slab and the calsil board will elevate the calsil board and provide a pathway for steam to escape.