Very basic reply based on a very generic rule of thumb. For generic construction, you can figure a WAG of 30-35BTU/Hr/ft needed in your bath. Again, that's a generic WAG. If your house is older and the bathroom has exterior walls, windows, a poorly insulated crawlspace below and a cold attic above, you may need more. If your house it tight and well insulated, then you may need less. Thus, the 30-35BTU WAG. You say the bb is 1520BTU, for your 100sqft bathroom that equates to 15BTU. Most floor mats give off roughly 12-15BTU on average. Check the specs and you might find one with a higher rating. So if you add 100sqt of 15BTU mat to your bathroom, then you'll be at about 15.2 + 15 = 30.2BTU/Hr/sqft. That might be sufficient, but that's also using the output of the RFH mat as an actual heat source versus simply a source of under-foot comfort. And it's also using both sources, the BB and the RFH mat, at 100% of their rated outputs. If the RFH gets overstressed, CL&P may send you a thank you card along with your monthly bill. Again...a WAG.

Others will answer with more detailed information. I have Warmwire by Suntouch installed in my new bath. I did it myself and the electrician wired it for 240, the Warmwire product is selected for either 110 or 240. Electrician said that 240 was better, I think it warms up faster. All should warm up to what ever temp you set it at. Wires installed: then with the plastic lathe I used over the wires: SLC being poured: With regard to the shower pan, I was told that I could place my tub onto the underlayment before the SLC. But I wanted the tub to be on top of the SLC so that is what I did. I did not run my wires under the tub, and kept 6 or 8" away from the toilet cutout. What are RPM mats? I notice that you do not have a de-coupleing membrane in your plan. Ditra is one. It allows a bit of horizontal movement to happen without cracking the tile. It is set on top of the SLC with thinset, then the tile is set with thinset.

We are moving our kitchen to a new area of the house to better fit with our lifestyle (creating a large great room and gathering space). It will be great! We live in a 1894 converted schoolhouse, which has created some special considerations. The current floor, though it has "character", needs to come out, as there's not enough wood left to refinish, has huge gaps, and is very uneven. We decided to put in radiant heat and then, after much research, engineered on top of that. It seemed that a floating installation was best on top of radiant, as it allows for expansion and contraction of the wood. We have been waiting to complete the floor process/project before moving forward with the construction of the cabinets, so that accurate measurements could be taken. (The counter will have a couple of windows pretty much right at counter height.) Per recommendations from our radiant guy, we are not running the radiant tubing under the cabinets nor island (waste of heat, attracts mice and bugs, isn't as good for food storage, etc.) The radiant will be laid in "tracks" on top of the floor. However... now, at the 11th hour, our floor installer brought up concerns about installing the cabinets and island on top of a floating floor-- that the weight of the pieces would cause buckling because parts of the floor would "float" while others would not move with the cabinets and island on top. (I'll admit, it does make sense.) He suggested gluing the engineered floor down to both keep it stable and not be effected by the weight. The floor guy says he can't in good conscience lay the floor as a float, so alternatively... My questions: 1) can engineered flooring be glued down over radiant heat? I have read some posts where this was a disaster, but maybe that's not always true. What would you suggest to put down between the radiant and the engineered? Are there any other things to be sure to or not to do if you glue down engineered floors over radiant? 2) could we set in a sort of "plug" that's the same height as the engineered along the footprint of the cabinets and island? The island has an extension on the sitting side that has and overhang with legs-- would you just put the legs on the engineered floor and not worry about those 2 spots of weight? How precise in the footprint do we have to be for the plug? could it be a tiny bit smaller so the floor would LOOK like it goes under the cabinets? how else could we elegantly mask where the floor meets the cabinets? 3) got any better ideas?? We have FINALLY begun to make this project a reality, so it's disappointing to come up against snags now. I can't find much info about installing islands and/or cabinets on floating floors (radiant heat or not), so your advice is very much appreciated.

Hola, Sorry, forgot to post layout: And no, we're not thinking of using our huge fireplace as a heat source. My kids have asthma, so all the tiny particles from wood burning or pellet stoves are not good for the kids. And I don't think they're that environmentally friendly. If we have the money, we would do geothermal heating. Here's our house in about 20inches of snow last year (does this help your decision, since it's nice and warm today?): plllog: "You have young children. You have a budget...Then the children can spread out their painting projects on the floor, roller skate, or whatever. Real linoleum, such as Marmoleum, is an ecologically friendly choice...you can easily replace it when you decide you want hardwood. In fact, you can do the subfloor as if you're getting hardwood... Then it's easy to mop. And you can make the change when the kids are older and you feel like spending the money--or not." These are my thoughts exactly!!! roobear: "Hardwood is better for resale, it would add value to your home, it can be refinished etc. Plus, it would fit the period and style of the house better." EXACTLY! The flip-side of my thinking as well. If I'm going to do hardwoods later, why not do them now and enjoy the benefit of the flooring, rather than pay twice? I've also thought about the heated rugs; the Japanese use them all over their house. circuspeanut: "have cold feet 6 months out of the year" Argh: sometimes it feels longer. cleo: "using engineered hardwood floors" Great idea, but because we installed some in our previous house, I really did not like them. My main concern w/ them is wear and tear, especially in between the planks. What happens if water (or raw meat juice) gets in between and swells the ?particle boards, etc? lovilynne: "have you considered DIY wood" Oh, while my house is not historical, it seems like it with the uneven floor, no insulation in the walls, etc :) We are DIY the hardwood floors for the 2nd floor right now. The learning curve was HUGE for us. And I'm not sure about my skills w/ hardwood floor over radiant heat. "they make a special heater to go under the cabinet" Oh!!! Can you please tell me more? Do you have pictures to share? Hmmm...