I'm looking at a lvt job which has piped ufh between the joists comprising of a layer of insulation, then the piping and then screeded with a sand cement mix till flush with the top of the joists. The job would be left for me at this stage still requiring a sub floor as the joiner doesn't want to take responsibility for anything concerning ufh. I'm going to call a chipboard manufacturer Monday but I would have thought chipboard followed by ply would have been adequate but I don't know. Does anyone know much about it?
Its worth bearing in mind the tog rating all floors have a tog rating and you don't want to be reducing the specified tog rating for the sub-floor, anything used to go over the heated sub-floor or is used in conjunction with underfloor heating also has a tog rating, some of which will raise or lower the sub-foor temperature. Not sure I understand the joists part mentioned, would I be right in thinking the pipework is running through a plastic castellated cradle system which is fine, or is it running through timber joists to which the final pour of concrete will be leveled off to. Which would concern me slightly in the sense that the timber joists will suck up the moisture in the concrete causing them to swell. If you cove these over with chipboard as suggested, the moisture will be trapped and may cause one of 2 phenomenons, the joists will rot and the whole place will smell like it has dry rot yuk, or when the underfloor heating is turned on the heat from the pipework may cause the timber joist to dry out to rapidly causing them to potentially twist or split and lift the floor you've installed over them. Granted that's worst case scenario I may just be belt and braces.
Thanks Jay, the condensation part is my main concern as it is with anything heat related. What I do know is the air space needs to be kept to an absolute minimum ie no air no condensation but changing temperature and timber makes me uncomfortable. I think the pipes run between the joists on top of a layer of insulation. I've checked a couple of web sites and it seems to be a recognised system. I found a diagram and it shows chipboard on top. Maybe I'm belt 'n braces too and I'm just looking for reassurance.
