Bricking inbetween joists on ground floor suspended timber floor

My builder is delayed returning to site, and I want to get the floor down, but before I can do that he needs to brick in between the joists where they overlap on a dwarf wall under the floor. I feel I can undertake this task so I can crack on with the floor, but wondered what the normal way of doing it was. One course, two courses, up level to the top of the joist, up to meet the underside of the insulation? Joists are 9x2 resting on a block on its side and 100mm PIR insulation, and it will not have the wall continuing above floor level, it's just a mid-span point for the joists to rest on.

Resting joists on 100mm insulation, if thats what you mean, sounds like a bad idea. So does the block on its side.
If you mean insulating the joist bays - then fine but no need for the block.

The usual way of building knee walls is that they are brick built, and provide for honeycomb ventilation, with a DPC under any wood plate or joist.
An Access opening must always be left for anyone who has to crawl thro the knee wall.

As above you wouldn't normally brick/block between the joists, if you need some lateral stability then spike the joists together & fix timber noggins or herringbone struts between them

Thank you for your replies. I've not made myself clear, but you have answered my question!

The joists are going on top of the wall, with the insulation in between, not underneath.

The wall is only two blocks (on edge) high, with a 200mm gap from the underside of the joist and the top of the ground build-up, so no room for future access! Even if there were no gaps left in this wall, which there will be through the joists gaps even with 100m insulation between them, both sides have adequate through-flow of air for ventillation.

I think I may have been thinking that this area needed filling by the builder when in fact he was only referring to the ends of the joists, where the inner leaf will continue up to create the wall. With the noggins that are already installed in between the 9x3's it did feel rather overkill.