Thanks for all the input; it's been really helpful. Shanghaimom, I did a 'step test' with a 12x12 marble sample I had on hand, and you're right; it is so much colder than the tile. That has convinced me to install floor heat, even if it's only a secondary source. I had no idea that hydronic toekick heaters existed; the quotes I got all mentioned 'electric fan toekick heaters', and I didn't want to go that route. When discussing with my contractor last evening, he was very supportive of the hydronic solution; now I just have to make sure that the unit will fit under the 'door' side of my vanity (will need to access it for service, so it really shouldn't creep into the drawer side of the cabinet.) Fingers crossed! Mongo, thanks! I'll do my homework on the BTU calculations; thanks for pointing out what to look for. Lynneblack, thanks for the vent/fan/light combo idea. I've read on the boards that the Panasonic is a great unit, but one of the two items I'm keeping from the current bathroom is my Nutone melon vent fan/dimmable light.

First timers need to know what to look at. First timers in heated floors need to know that heat is related to your insulation and your building's structure. The thing to consider (and to express in your first post) is your subfloor material, how well insulated it is from your building envelope, and what you will be expecting from a warm floor. It is entirely possible that you will get a great warm floor that heats up fast, and it is ALSO possible that you will get a weak warmth that underperforms. The choices you make about everything other than the membrane are the factors. The membrane is "topical", on top, above the heated floor. The specific membrane you choose is not relevant to any discussion about heating. Focus on the bigger subjects.

Unfortunately gas is not available but I do have a 250lb propane tank and currently have an oil boiler with baseboard radiators. I purchased the home last year but will be doing extensive renovations in the upcoming year or two. It is a center staircase cape cod style home that will need the hardwoods and sub floor replaced in the front two rooms (~60% of first floor) due to a broken pipe while the previous owners owned the home and according to my contractor improper layout/thickness of subfloor. I was thinking of doing warmboard subfloor since everything is coming out anyways and a radiantec distribution system. Everything is in the planning stages but I want to save myself as much headache as possible. The house currently has no central A/C and I (and the REAL boss) am not a fan of typical mini split head units so we where going to use both ducted and cassette units where possible.

jenny_nettles , thats a great question! For radiant heat you will need very high quality Engineered Plank. Here is a helpful article specifically on how to pick high quality Engineered product. Try to start with a product made in the USA or Canada. Look for at least a 5/8" thickness and wear layer that allows for refinishing.