Wet joists and some floorboards

[Gary111]

Hi all, I opened the access hatch on my 1930s terrace the other day and found the joists were wet for the first couple of feet from the front wall they don’t seem rotten but I think they were like this maybe 6 yrs ago when I last opened it.
There’s a small area of expanding foam, Dont know if this should be removed, just a bit though.

It looks like it has had chemical dpc injection holes.
Not sure if it could be condensation ? house has airbricks, look a bit small though ? And has a concrete slab extension at the back.
Has smelled slightly damp under stairs too.
What should I do ?
Thanks

[wine~o]

That is pretty wet, chances are when the extension was built and the slab laid the airflow front to back was disturbed. The answer is more air flow, ie more airbricks.