remove load bearing wall: support 1st floor joist ends?

[rsk1]

I am removing a 2m section of cavity load bearing wall and fitting pair of rsj's. The first floor joists butt into the wall above where i'm planning to open out. I've been told i need to support the joist ends to take weight off the wall, as well as supporting the wall with needles or strongboys above the planned opening.

My question is : if i'm supporting the wall above the planned opening, why do i also need to support the weight of the floor that bears on it? It's an extra set of props needed and i'm not sure why i would need it, unless i think the weight will be too much for 2 pairs of props.

Second question: half of the 2m span has an old brick arch in the wall from there used to be a window. Is there any point inserting a needle underneath this arch or can i assume it is self supporting? in which case I might only have 1 pair of props for the 2m span

 

[tony1851]

Just a couple of props under the floor joists, and one - or at most two - strongboys supporting the outer skin.
One or two bricks will work loose between the floor joists, but it's no big deal.
Don't try and support underneath the arch at any point as it will come down as sure as night follows day.