Our house is made from mass concrete and is approximately 80 years old. Apart from the hallway, the downstairs has carpeted wooden floors and there are air vents at the base of the external walls. Beneath the floorboards appears to be just sand and earth. We want to replace the existing carpets with solid wood floors. Some of the old boards are damaged from moving pipework around and the boards in one corner have rotted from a previous damp problem. There is also a strong breeze coming from below the boards when the carpet is lifted.
Is there some sort of insulation that we should consider laying below the existing floor? Should we block up the external vents to prevent the draughts before laying a new solid wood floor on top of the old boards? Should we consider trying to reclaim the old boards (given that there is some damage) or simply lay the new floor on top of them? Any advice would be greatly appreciated.