My bungalow's suspended timber floors are to have Rockwool or similar fitted below.

Would I be ill advised to have wooden floorboards as the finished floor in the kitchen and bathroom?

I'm not so concerned about the condition of the wood from regular small splashes and drips, more what happens if a larger splash makes it through to the insulation.

Thanks.

I would use rockwool batts squeezed and pushed into place, belt and braces using chickenwire or similar staple-gunned in place. Hammer in all the floorboard nail heads, sand the floor (rent a big lawnmower type sander), varnish, seal the cracks up with a flexible clear sealant, I'd guess like this one:

https://www.screwfix.com/p/ob1-multi-surface-sealant-adhesive-clear-290ml/434jf

I think you need to prevent warm high absolute humidity house air getting to the insulation and condensing in it as it cools. The cooler underside will be low absolute humidity, so best to leave vapour open as a backup in case some water gets into the insulation from above.

Nb: I'm just a diy-er...
We have varnished floors (but not suspended). I always use DiamondHard floor varnish, it takes 3 coats generally, and worn areas can be touched up after careful cleaning. There are tougher longer lasting ones, but I think they all have longer drying times which is impractical for us, and I think often smell which gives me a headache. We heavily sanded 20 years ago, since then have just locally cleaned or slight sanding & varnished when needed.

Thank you all for the replies.

As you allude to, owlman, one reason for the floorboards-only option is to keep the floor level with the hallway, but I could live with a small build up if necessary. The others are cost, warmth, and being free of having to commit to a tile/Marmoleum colour :)

The soil below was very damp and had caused rot in the joists and boards, but since laying polythene and sand this problem seems solved. There are also lots of vents and 1.0 - 1.2m of clearance below, so hopefully there won't be an issue on that side of the insulation.

My other boards are finished with Auro hard wax so that would be my first choice. It seems very water resistant and hard wearing.

I wouldn't worry about some build up between rooms. When I put insulation and resistive cables under my new hallway stone floor there was build up of levels to the adjacent bedrooms and guest loo. I fitted polished oak ramps covering the whole width of the door casings. It's hardly noticeable now and is quite a nice feature.

I thought that the recommendation was to put a VCL between floorboards and joists when insulating between joists on a suspended floor. If so this would solve any problems of spills going down into the insulation. But of course would do nothing for spills staying between the floor boards and the VCL where in some areas (e.g. just outside the shower) persistent damp could be a problem.

But

Posted By: owlmanHowever, timber flooring in wet rooms wouldn't be my first choice. I prefer ceramic or stone coupled with electric under floor resistive cable, with suitable controls.

I'm with owiman here.

Posted By: kristevaWhat exactly does this polythene and sand involve WeeBeastie? I'm interested because my floor gets damp too.

I believe he's just referring to laying a DPM on the ground with some sand on top to hold it in place, but he may have laid sand as a blinding layer before the DPM. Or both?