Raft foundation - do I need to underpin?

[Dhjones]

Ok let's look at this from a different view.
A door... a door is a door, I'd be hanging a door, I wouldn't be hanging the stiles, jamb and head.
Just like a door, a raft is made up of different sections, like the toe, the slab. As a whole it's a raft.
Today I ate some skin and some pulp but left the core and pips. ??????????
I had an apple!!!

 

[^woody^]

No, let's look at it this way. A slab of concrete acting as the foundation is a raft.

 

[stuart45]

One that's about to sink if not built correctly.

 

[Dhjones]

No, let's look at it this way. A slab of concrete acting as the foundation is a raft.

Is part of the raft.
So the toe, is this part of the raft or the slab? If the toe is part of the slab, what's the purpose of a raft being identified as a raft?
The beam section... does this make up the raft being a raft or the slab?

So as I have it, that big flat square piece of concrete which is inside the perimeter beam and toe would be the slab, and when identifying all sections as one, the word Raft is now used.