Insulating beneath the floorboards to eliminate drafts would necessitate lifting each board, installing a net of some type between the joists and laying the insulation on that so as to press against the underneath of the boards when they are re-layed, which is quite a big job, and potentially could block free airflow to the underneath of the floor boards storing trouble for the future.Depending on whether or not you have a carpet, or plain floor boards, there are other options available, both of which we have used and are pretty effective and more cost effective, because wood itself is quite a good insulator.For carpeted floors, seal the gap between the floor boards using a decorators flexible sealant such as calk (not mastic or silicon as they are troublesome to remove if you want bare boards in the future), lay thick under carpet paper (overlapped and use a staple gun) ensuring it is pushed underneath the skirting boards, then put down the carpet grips. Use a high tog rated underlay such as Envirolay 54oz felt or Swaledale 54oz wool underlay (we used Swaldale, not cheap but very, very good) and use any off cuts to push in between the floor boards and the skirting boards, then carpet on top as normal. The effect is quite dramatic for warmth, elimination of drafts and acoustics strangely enough, plus, it does not affect the airflow required under the boards.If, you have exposed floor boards, then normally you would seal between the boards at the time of sanding by using a clear wood glue/resin, mix in the saw dust from the sanding and use this mixture for sealing (as it should be the same colour, but you will be able to notice the filling afterwards), remembering to use a felt type material pushed between the floor boards and skirting board. This will reduce significantly, if not completely the drafts, but it won’t be as effective as having the carpet option.
Bosko Novakovic ● 5082d