Bathroom renovations - australia? we're in a brick and tile home and we've purely removed the...

we're in a brick and tile home and we've purely removed the bathtub from our adjectives bathroom.

the bath be tiled contained by and when pulled out, we discovered it was lay on sand and not the concrete slab as assumed. when we dug through the sand to find the slab, we just kept digging. the homes concrete slab doesn't look similar to it goes underneath the tub??? is this normal? or is the tub supposed to lay on top of the slab?
Answers:    Looks similar to someone saw the tub sitting there and arranged to build a house around it! Just kidding, it is not typical to put the tub in the sand it should hold been placed on the slab. With fiberglass tubs frequent contractors will put mortar on the slab and then place the tub contained by on the wet mortar, this will support the floor of the tub once the mortar is dry. This will prevent cracking within the tub if people bound around in it or if a individual is very bulky.
I don't live in Australia but here surrounded by the US the tub is installed on top of a concrete floor or the subfloor on a pier and plank structure. I've been within construction for over 30 years and I have never hear of your circumstances.