Any suggestions to improve this suspended Floor?

[steggles123]

All,
I have an old detached red brick house that has suspended flooring and there's water related issues in the middle section either side of the front door.

Outside: concreted upto the front door and either side landscaped. There are low air bricks. Guttering is not leaking and running directly in new underground drainage fitted.

Inside Property:
There are no air bricks around the front door area ( where the problems are ) due to concrete. Two walls either side of doorway - right side stairs left side another room where air bricks is.

The brick wall separating the rooms does not have any ventilation gaps / air bricks that leads into the main doorway section.

Also cannot see the air bricks on the inside wall.

Guessing that's there is a cavity wall as polystyrene balls came out when faffing with door architrave and old plaster.

At some point in the past the area has been sodden as part of joist is rotten and appears there's a thin bitumen dpc ( I guess failed ).

The ground further in appears dry but there's some white area - mould or salts?

High rainfall area. This side of property in question gets lots of wind and sunlight daily.

Any suggestions to remedy this at all?

Thank you.

 

[steggles123]

Some additional imagery.

 

[steggles123]

Actually there is a large gap between walls leading to front door. which I think has been there for a while. I'm assuming this is sufficient to move ventilation throughout the floor?

There is a supporting wall holding the joist with a brick length gap between the external wall. Behind the boiler pipework is where the first air bricks resides. I can poke a rebar through majority of holes and pull it from inside so hole does have airflow available. There is a brick removed where the air bricks are so there I presume a cavity wall.

The earth between the joist wall and external wall has moisture in it - ( I scooped a layer up and placed it on an old floorboards and it's absorbed moisture. )

I am going to careful scoop damp earth out between these walls to hopefully to improve drying. Within the wall holding the joist there are inch gaps presumably to help ventilate.

There is some mortar that needs replacing near doorway that I am aware of.

Would a third air brick help? A brick higher would come close in-between floor boards.

Any suggestions?