Anybody know what this is called....? - And how to fix it?

[da02uk]

Please excuse the pace of this thread.

We have now moved on to possibly the real cause of our musty smelling living room.
On further exploration of the floor and hearth areas I have found the concrete that is under the carpet and foam underlay to be very damp. This has to be the cause of the smell right?
My father reckons i can get a resin to 'cap' it, by cutting channels all around and pouring in and over the top. He feels that putting poly sheeting and concrete will only end up having to be done again due to it cracking, plus the removal will be messy.

Does anyone have any thoughts on this?

[local patios and driveway]

whats the condition of the chimney stack? if in bad repair this can cause all kinds of related damp issues. check the lead flashing etc, specifically the top, while the top of the chimney can seem so far away from your problem on the ground floor its not an unusual problem