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How much self-leveling concrete do you typically add above electrical radiant heat wires for LVF?

LVF manufacturers recommend 1/2" of concrete on top of any radiant heat. Since the wires are 1/4" thick, this would be 3/4" in total of self-leveling concrete. Does that seem like too much? It doesn't seem like anyone adds that much material in tutorials even when planning to install LVF. I understand that it is to protect the LVF from the direct heat of the wires, but wouldn't 1/4" of 3/8" above the wires be plenty?

Also, would you perhaps embed the wires in mortar to limit the amount of self-leveling concrete needed if going for the full 3/4" suggested?

Thanks

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  • 2
    why would you question the manufacturer's recommendations?
    – jsotola
    May 15 at 15:12
  • I'm sure you don't have to do that, but I'd imagine that you'll void the warranty on your new flooring if you don't.
    – FreeMan
    May 15 at 16:59

1 Answer 1

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Self levelling

  • reduces walking and trowelling around the wires
  • may reduce tiny air pockets around the wires and so improve thermal performance

Some minimum thickness above the wires provides

  • adequate protection around high spots in the floor or spots where the wire floats up a little between brackets,
  • distribution of heat to avoid stripey hot spots in the floor. That's more important with vinyl than with tile, where most of that half inch will be provided by the thinset and tile itself.

How much thickness provides enough of these things? Well apparently according to the manufacturer it is half an inch.

Your question is whether the manufacturer is wrong. There's one way to find out :) but obviously the internet has not conducted extensive and systematic testing to prove that 3/8 is good enough, and if you reduce the thickness a bit, manage not to damage the cable, and end up with a floor that performs slightly poorly or slightly unevenly, you will not know because you'll have nothing to compare.

When I installed electric radiant the manufacturer provided free video supervision to make sure I followed their recommendations. That's how important it is. I would follow all the instructions from the wire and flooring makers.

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  • Thanks. I do like to follow the instructions, but it seems like nobody else does in tutorials so I was wondering why there was a discrepancy. Maybe they were doing it in layers or something as 3/4" is a lot to pour even in a small room. Also, the instructions could be clearer that it's a 1/2" above the wires, which is 3/4" in total. I needed seven bags so I had everything ready with seven buckets and an assistant. I got four going and then my assistant did the other three while I poured and used a squeegee. It worked out well but still stressful.
    – ARClimber
    May 17 at 11:11

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