concrete subfloor 2" 'void' vents and mould treatment

[oxfordite]

Rented house, ~1967 built. Gas CH. Foam cavity insulation ~1980s.

I had flat roof extension (35 years old) leak repaired - Ivy removed, facia and new gutter fitted, with flashing to close gap between facia and ajoining corrugated garage roof. Leak fixed.

Now to the internal damp problem. Smell of mould, so threw out carpet and underlay.
Chipboard... lifted most discoloured board (discolouration only near to leak): several colours of mould on underside.
There is a 2" void!! 2" timbers resting on little pieces of roofing felt (they too have moulds growing).
No air brick vents. No plastic membrane. no rot to skirting board.
After stripping lining paper, one vertical of plaster is wet - foam cavity insulation in 1980s.

A small task: fit laminate floor has become major due to poor work 20-35 years ago...

Question:
What do I need to do to get boards down at same height with laminate floor, to see no further damp/mould problem and healthy habitable conditions?
What materials? What mould treatments? What DPC/vapour membrane/air vents?

It is a bedroom and its occupant has a sensitive nose for mould.

Thank you all.

 

[ree]

Suggest that you post pics.

 

[oxfordite]

It turns out to be not so bad... discoloured chipboard did have mould on the underside. Some of the battens supporting it did too - predictably near the damp wall - failure to maintain flat-roof, gutter, etc.

So the only question is what products are recommended for treating concrete and wood and plaster to kill moulds?

I realise that the adjoining garage is very humid - so that outside wall of the bedroom will tend to be damp: I need to go do the maintenance: remove all algae from the corrugated roof, and all the ivy - clean it so that it is dry more often.
Then to fit some vents:
http://www.manthorpe.co.uk/Building...Underfloor-Vents/Refurbishment-Weep-Vent.html
Maybe a few at the back to allow some airflow through the garage, and several in the adjoining wall to help ventilate the cavity with its old foam insulation.

The worst problem is that whoever laid the screed did not lay it level... makes replacing timber to support the new chipboard more time consuming and irritating.

With a DPC on top of the chipboard, any mould smell should be contained beneath the floor but the room will no longer help the timberwork to breathe - so I should properly fit an air brick, inside and out near the damp end of the room... we'll see.

Any thoughts on mould killing products?
Thanks