Broken hearthstone first floor bedroom

[Old bodger]

where a fireplace has been blocked up in a first floor bedroom, there is a hearth set into the floorboards which is breaking up. This appears to be a screed of something, around 1" thick, laid over what is now rubble in the gap underneath. I would like to repair this and paint over (am painting the floorboards) but not sure how to go about it

 

[vinn]

Such hearths were usually made from a single stone hearth piece.
Your hearth could be a screed of sand & cement - lift some of the pieces out & post a pic of whats underneath the surface layer?
What is supporting the "rubble"?
Is there any signs of disturbance on the ceiling below?

Note that your hearth is going under the skirting back into the fire opening.
Does the blocked off chimney flue have a vent inserted in the blocking material? It should.

 

[Old bodger]

View attachment 117020
Just seems to be decaying cement slab

 

[vinn]

Your attachment wont open?

 

[Old bodger]

Sorry - is that ok?

 

[vinn]

There's no way to "repair" the broken stuff, neither should you want to "repair" it - its too fragile.
What exactly do you intend to do with this hearth and blocked fireplace - if anything?
I did ask a couple of leading questions above?

If you want to retain a hearth then come back but if you want to demolish it then also come back.

 

[Old bodger]

Think I might just demolish it and cut a piece of chipboard flooring to fit in the hole - too difficult to match the floorboards they're at a stupid angle. I'm painting the floor. Thanks for your help

 

[Old bodger]

There's no vent, but the fireplace was blocked up around 55 years ago. From feeling around the slab ends just under the skirting. The chimney stack has been removed and there's a range cooker and extractor in the opening downstairs. No damp in the chimney. I just want to make the floor sound

 

[vinn]

In that case: remove all the surface S&C, and the rubble below the surface, hoover it out, and then post a pic.
If you are lucky there will be a kind of platform below the rubble.
The new floor boards can be cut and laid to patch the old hearth footprint.

 

[Old bodger]

Ok, done:

Bricks, not level. Joist just under the boards at the front, cut against the chimney breast. Bricks drop away by around 2" front and rear

 

[vinn]

Thanks for the new pics.

Leave the bricks alone.

You now have alternatives:

1. you can drive a few long screws or nails into the surrounding joist box (its known as trimming) leaving them sticking out.
You can then fill with a semi-dry concrete mix and smooth off the surface.

2. First, firmly fix a piece of say 2" x 4" across, almost below the skirting - this will act as a bearer for the new T&G boards.
You could then fix some 2" x 4" to the trimming joists - the 2" x 4" will act as support to pick up new T&G flooring.
Alternatively you could cut back the in-place flooring to sit half-way on the trimming joists - this will give bearing for the new flooring to be fixed to.
To do this first remove all nails and screws in the old boards.
Pilot hole your new screw holes to prevent splitting.

 

[Old bodger]

Thanks - I think I will go for the second choice, I'm happier with wood than cement!