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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.

Hi. Don't block off the vents, these are necessary to create and air flow beneath the floor which helps prevent the build of excessive moisture.

Your options here are to either place insulation between the joists beneath the floorboards, using polystyrene 2" or 4" or Fiberglass bats, held up by metal rods or treated battens, but this can be tricky as you will need to get below the floor to do this, unless you intend to rip the old boards up.

Alternatevely you can use an underlay beneath the new solid wood floor, various types are available, but the existing floor should be made good first.

Hope this helps
Ken

Thanks Ken. I had a look at some of the underlay options including Tuplex but I'm not sure if it is suitable for anything but a floating floor over concrete.

Maybe the best (though most expensive) option would be to pull up the old boards completely, insulate between the joists and then put down a 1/2 inch ply subfloor. Any thoughts?