how to stop new floor getting damp?

[TheMitchells]

In our renovation of a Victorian end terrace, we have been replacing the lounge floor beams as they had been rotting where they sat on the cellar wall, which is reasonably damp most of the time.  In most cases there was no dpc. 

 

as can also be seen, as we removed the flooring, the chipboard was quite damp too with mould.

The make up of the floor was as follows:

beams,  with rockwool insulation squashed between and in some areas, around the front door and alley wall, the rockwool was wet.

tongue and groove chipboard - some of which was damp.

upside down gripper rods - to hold the insulation in place.

foil backed insulation sheets.

pine tonge and groove.

 

In two areas, the chipboard was quite rotten and could be pulled away with fingers.

 

So we have removed all the flooring and the old beams, fitted a new extra thick beam across the whole floor and then put in new joists.

 

 

We have sat them on dpc, with engineering bricks, slate and strong cement used to level them to the correct height.  Then we have laid new 18mm T&G chipboard across the whole floor.

 

My question is how to insulate the floor to provide a comfortable lounge without any draughts while avoiding any future damp issues?  This house is to sell so we do not want to spend too much yet still want to do a reason job.

 

We want to lay bamboo flooring above the chipboard.  but do we need any membranes?  and how best to insulate?  The cellar could always have damp issues, particularly in that corner, although we have added an airbrick to the front so there is now a cross flow of air to the other airbrick under the bathroom.  so if we just add Earthwool between the new joists, will that get damp and eventually rot the new joists and chipboard?  Or would a thin insulation go on top of the chipboard before the bamboo?  We dont have much head room, only 2.1m in the lounge, so do not want anything that will reduce the height further.

 

Any suggestions/advice.