Make good hearth after chimney breast removal

[Cricritherenovator]

Hello everyone,
Please, I would like some advice to finish off with the ground floor of my chimney removal project which is on the party wall with my neighbour. Gallow brackets have been fitted in the loft and the bricks removed up to the ground floor. First floor bedroom has been made good replastered, joists sorted and floorboard added.
The house is mid 1940, solid wall with slates as dpc. The ground floor is a suspended wooden floor.
Now I am left with the ground floor chimney hearth, all the old concrete has been removed of it as it was loose now I am only left with dirt and hardcore. There is no particular sign of damp everything is pretty dry. Basically what should I do now out of the 2 options below?
Option 1- Cast a new concrete hearth with 20mm gravels on top without careing about adding a dpm basically the same as it was before without the chimney breast and forget about it move on basically?
Option 2- Make a new suspended floor in this area, by removing all the dirt to an acceptable level and remove a brick on each side in order to get some air flow into it. Using some C24 treated timbers trested on the end.

If option 2 is the preferred option I will need some help with the layout of the new joists. I don't want to go to exteent to lift up all the floor boards to put new longer joists etc.

See attached pictures of the 2 possible suspended floors I had in mind. With some questions into it.

The timbers already in place on the pictures are the stud wall which will be fitted to the wall and cover the old fireplace wall in order to level it up and pu some sound insulation with the neightbour.

Thanks in advance for some help

 

[Cricritherenovator]

Anybody to give me some help please?
Thanks

 

[Nige F]

Option 2 - because the wall might be damp-ish against the timber in option 1. Not aware of any special joist hangers (not a builder) hope this helps

 

[Cricritherenovator]

Now I got all all hearth cleared out to concrete base.

I found that the 3 joists are rotten underneath in the area resting on the hearth wall. But it sounds like an old issue as everything is completely dry (joists, wall, floorboard., hearth hardcore). I also found that one of these joists is not resting anymore on the sleeper wall by about 1/2 inch which I plan back up with tile and mortar. See attached pictures for all these

In a way I am happy that I didn't just let the can of worm closed by self levelling the hearth.

Now my plan is to bolt and glue new small joists 4" x 2" to the existing joists with an overlap of 2 foot. Making them resting on the hearth wall pack up if needed. Then attaching to the house main wall with some Simpson strongtie joist hangers (the one with a flange sunk into the mortar).

Would it be ok or should I overlap them up to the sleeper wall in order to have them resting on it (but that would be a lot of floorboards to lift up).

What type of bolts or nails should I use link them together and how many and to what distance from each others?

 

[JohnD]

Have you dug out the old hearth, and the damp rubble under it?

 

[Cricritherenovator]

Done already all gone as I said in the last post. Now time to lay the joists up