If insulating under a suspended timber floor is not possible, how can you stop the drafts between the floor boards?
Looking on the Web is a great way to research the best way of doing something. Caramel Quin wrote a great blog some time ago looking at ways to draft-proof stripped wooden floors. http://www.guardian.co.uk/environment/blog/2011/dec/16/1.
Some timber and floor boarding companies had good blogs on the ‘filling the ‘gaps’ http://www.woodandbeyond.com/blog/three-methods-to-fill-gaps-in-wood-flooring/ but many are for where you have not yet sanded the floor.
I thought seriously about using wedge-shaped pine slivers http://oldpinecompany.co.uk/acatalog/About_Old_Pine_Slivers.html they are possibly the best and the most ‘green’ solution but I didn’t want to sand the floor again.
I needed to eliminate the draft but I wanted to retain the look of the golden pine boards broken by dark lines, which meant retaining the gaps. This stance eliminated using any kind of filler option, which can often fill both the gap and half the floor board.
Having considered all the options I opted for StopGap http://www.stopg-p.co.uk/ . It is thin V-shaped plastic on a roll that you push into the gap, down to the joist level and it opens out to fill the gap. It can be used to fill 1-8mm gaps in both floor boards and skirting boards. If you are going to re-varnish the floor this needs to be done before fitting the StopGap. To ensure the StopGap works as efficiently as possible the gap between the floorboards need to be free from debris and any drips of old varnish cleaned off the sides of the floor boards.
I wanted to make the floor as draft proof as possible so to finish the floor I ran a strip of painted timber beading around the base of the skirting board and sealed this with an acrylic interior frame sealant.
The result; the ground floor is definitely less drafty and the room feels noticeably warmer. The ‘under the floors board’ insulation option would have been better in terms of heat loss but it would have cost over £1,000. So I have stopped the drafts, kept my golden pine floor boards (some of which I have covered with rugs to give that real feeling of warmth) and the materials cost less than £150.