Original Wooden Floor

A basement room? A cellar, or something habitable?

Use papier mache. If you insulate under, and stuff falls down, it will eventually turn into filler!

I should use Ronseal Heavy Duty Floor Varnish, making sure it dries between coats. If you want a matt finish, use matt for the last coat, and gloss under. Diamond glaze is a waste of time on softwood floors, and isn't much tougher anyway.

The conventional solution is papier mache, or a mix of wood dust from the type of wood plus PVA.

It's worth insulating under the boards between the joists. A good solution for that wood be pieces of 50mm thick Celotex. It would also deal with most of the draughts so you might not need to fill the gaps anyway.

Definitely don't use gloss yacht varnish. First of all it will look like plastic crap or worst still, laminate floor. Secondly to do anything to it in future will involve stripping and sanding the whole lot.

A solvent based satin finish will give the best compromise between a natural wood look and maintainability.

Carpet works remarkedly well.

In a kitchen?

Yuk. That's worse than carpet in a bathroom

Whoops - missed that. Okay, tiles then :-)

Certainly does. Try FLOTEX.

Dave

I used ( and am using again for another floor ) natural wood colour acrylic frame sealant, the sort that comes in a tube that is dispensed by one of those squeezy guns. The only thing that I do that makes it tedious, is, on the basis of belt and braces, I also stuff sliced-up foam insulation ( of the sort used for lagging pipes ) into the gaps first, as it's not possible to guarantee that the wood will not open up slight gaps in the sealant after a year or so. I had this happen on the first floor I used frame sealant on, and the gap was wide enough in one or two places to feel cool air whooshing up from below on a windy winter's day. I simply squeezed in more frame sealant to stop up the gap, but as I said, I am caulking the gaps this time with foam insulation to prevent any air leaks even if the wood moves a bit. Typically there is room for a depth of 6-10 mm of frame sealant on top of the caulking. I suppose the caulking is not a strictly necessary step. It is best to use masking tape carefully laid on either side of the gap when applying the frame sealant to stop it sticking to the floorboard top surfaces when you smooth the sealant down

Andy.

Osmo hardwax Polyx-Oil is much nicer than varnish.

Do you have to worry about the lack of fresh air circulation causing damp/rot etc?

it would be a prerequisite to make sure that there are no sources of damp.

Secondly, as a precaution, it would make good sense to spray the underside of the boards and joists with a dry rot fluid.

Since the Celotex would be in contact with the boards on the underside, there wouldn't be any unventilated voids anyway

I got some thin battens made up which were slightly tapered in section. (Cut on a bench saw with blade at slight angle) Sizes depend on the gap width. Say 6mm wide at the top and 4mm at the bottom. Thickness would need to be a little more than the that of the floorboard. Length = length of gap. Tap to wedge into gap until it is flush. May require cutting out a little on the bottom where it would otherwise foul on the joist.

mark b