"Damp" fireplace

[jimbo17]

Just in need of some general guidance to do with my fireplace . First time buyer . Took down a fake wall and found fireplace which I've opened up

There was efflorescence / salts and dampness around the bottom , so I've dug out the hearth and seen that my floor slab was around 2 inches thick with clay soil underneath.

So the question really is from the pictures how can I re-lay that floor and keep dampness down

 

[blup]

The damp might come from the old hearth bridging the dpc (in the wall) if there is one. If so use a plastic membrane on the clay floor and let it into the bricks above dpc/external ground floor level, and lay a screed over it.

Blup

 

[jimbo17]

No dpc to be seen sadly wether it be slate or bitumen . Or foundation, once I get so far down the masonry just stops . Seems like my house is just built on soil

 

[blup]

You may able to add a plastic or epoxy membrane on top of the concrete slab but would need to ensure the damp didn’t migrate to the walls without protecting them

Blup