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Community and Q&A

Warm bathroom floor

Jeffrey O'Donnell | Posted in General Questions on

I’m about to start building a house in MN with finished concrete floors. This is climate zone 6, all electric house. We will have one minisplit providing heating/cooling for the entire main floor. My question is in regards to heating the master bathroom floor: Does it make sense to run electric heating cables in the slab for this small area? I do not want to add tile, which would raise the floor height, just to add ditra heat or similar. I’m concerned that it will be an energy hog since it will have to heat the whole slab. Any other options? Just trying to make my wife happy.

r33 walls, r10 subslab insulation and this section has a 2nd story above it. Thanks! Jeff

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  1. Stephen Sheehy | | #1

    We also have a polished concrete floor. We placed the concrete in the bathroom lower than the rest of the slab, low enough to allow us to tile the floor and have the finished bathroom floor at exactly the same elevation as the rest of the floor. Ditra heat went under the tile. Wife is happy.

    I'd go with 4" under the slab in MN. Look for reclaimed foam.

  2. Ethan Foley | | #2

    In most of the floor plans I've seen with a single minisplit, the ensuite is hidden away in a corner with two exterior walls and without much exposed partition wall area to the main area with the heat source and with two door separating it from the main heated area. It almost certainly needs a secondary heat source. You should double the foam under the radiant heated area, the backlosses on radiant heat are quite high without adequate subslab insulation. Take a look at your Manual J room by room calc, how many btu/h does the ensuite need?

  3. Andrew C | | #3

    Electric toe kick heater?
    It seems that a toe kick heater would be cheaper and work with any eventual flooring options. I suspect that it won't be used all that often, and not for long (ten minutes?). Pretty much instant heat.

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