Extending shower tray over electric underfloor heating??

[SuffolkLady]

Sorry, newbie here. If this should have been posted in the Electrics or Flooring section please feel free to move.

The previous owners installed electric underfloor heating in our ground floor bathroom, we cannot live without it as our only other heating in our home is the log burner but the heat from it doesn't reach the bathroom. We need to change some damaged wall tiles in the shower so while we're at it I've been thinking... Yeah, dangerous I know!!...

Our shower is in the corner, square and tiny but there is plenty of room for a larger tray. Installing a larger rectangular tray would go over a couple of floor tiles, under which there is obviously heating. The shower is raised off the ground to account for plumbing. We would have local tradesmen do the work but just trying to guesstimate how much work it will be as we cannot afford a whole new floor at present and rather like the current one. So my questions are... Can a raised shower tray cover approx 800mm of tiled underfloor heating with or without vents?? If we need to take up tiles and find heat mats running a long way across the room can these be cut and rewired or would we then be needing to take up the rest of the floor?? We don't want to start anything we can't afford to finish at this time and don't want to get tradesmen in just to be told it's not possible and we've wasted their time.

Many thanks for any help you can give. xx

 

[ericmark]

I fitted electric under floor heating to mothers wet room, it was limited at the time as to what could be used, the chemical type is best as self regulating, but needs to be either covered with a earthed mat or have a earthed braid, we selected the latter, since resistive also needs a sensor in the floor to stop over heating, first job was to lift old floor, 9" of insulation then marine ply wood, then heating mat, then tiles.

Lucky we also fitted a towel rail, as total failure, the floor felt warm, be heating on or off as now well insulated, we had sensor fail and stick in pocket, we had to lay the heating twice as the builder used out of date tile cement which did not dry and the first mat damaged. But the main idea was to dry floor, as mother an amputee, that was a failure, after a shower would take around two hours to dry, not helped as we used sculptured tiles for grip, but floor had to be dried with mop each time used.

Heating time was so slow, around 2 hours before room warm, and the extractor fan removed more heat than the floor put in, it was vary rarely switched on, once water on the floor even hot water the floor cooled immediately, bending down to feel the tile, once wet took an hour to warm up, and longer to heat room with fan off. So needed to be one 3 hours before the shower and 2 hours after to dry floor, as said we would mop floor instead.

The problem with UFH is maximum temperature is 27°C for the tiles, in our case room assessed from hall, and hall not very warm, since the LABC inspector insisted on a fan, within minutes wet room same temperature as hall, it was a total waste of money, as said lucky we had a towel rail.

Although we put in 9" of insulation, 6" likely enough, we had to dig floor up anyway to do the drains, the whole idea was wheel chair access so no lip on shower tray, all built as wet room, the builders walked off the job half way through and it transpired not only the glue was wrong, the sink cupboard disintegrated allowing sink to fall on floor, and found the door lintel only supported on one side, we fitted a power shower, and latter this had to be removed as the central heating boiler was changed for a combi boiler and power shower was illegal when pumping from mains.

All the hidden pipework then ended up surface when boiler renewed. Job needed doing as mother was an amputee, but it was a nightmare. But although UFH worked, it was not enough, typical bathroom extractor 12 watt moves 76m³/hr to heat that amount of air UFH will not be enough. Not sure about heat recovery units in a bathroom, but looking at £180 or more, and not sure how they handle damp air. One I looked at said "Overrun and delay start timers are also available" and 24 volt so likely are OK. But need to make enquiries.

 

[winston1]

Can’t see what any of Eric’s long post has to do with the OPs question!

I don’t think putting a shower tray over underfloor heating mats is a good idea. As to cutting out a bit of mat I doubt if that is feasible either.

 

[SUNRAY]

If the floor tiles are proper ceramic/clay floor tiles and securely fixed I can see no real reason why the shower tray cannot be installed on them, after all it is common practice without UFH and I see no reason why the shower should affect the UFH.

 

[RobTi]

Get ir gun and you may be lucky and be able to baton missing the heat mat/wire, but I wouldn’t put pressure on it unless the manufacturer approves it