"Andy Hide" wrote in message
om...
Just curious to know if this type of construction was common on older
properties ? Also, on a similar subject, how would the slab of
concrete in front of each fireplace have been held up in an upstairs
room ?

Can't answer your first question but for this one in our case it was on a
wing and a prayer. The two joists had been shortened, then 'cross-joists'
attached between the ones outside at the wall and 18" back, then the wood
hollowed out at an angle and the slab dropped in it.

How it stayed there for at least 50 years, possibly longer is beyond me.

Removed the slab and replaced the joists.