Tell me about radiant heating.

Some people I know are renovating an old house back to the studs. They are currently discussing heating options, with radiant being the current preference. Over dinner this weekend they were disuseing this possibility, and several questions came up. I thought I would toss them out here for discussion so that I could get back to them and look like a research genius.
First off, they were concerned that they would need a concrete slab on their upper floors, and were not sure the structure would be strong enough. Their project also has fir floors with no subfloor, so the fir will become the defacto subfloor. Not sure if that is germaine. Another concern they had was the need for a floating floor, and what kind of floating flooring was suitable for a kitchen. Finally, will the cost be prohibitive and how DIY can they get?
Any other concerns or thoughts are of course more than welcome.

There are two main sub-types of radiant heat - hydronic, or circulating hot water, and electric.

For a room remodel, electric is much simpler - lay out the mats, wire ‘em up and lay the finish floor. The mats are about 1/8" thick. For your friends’ gut-to-studs job, hydronic is a viable option, but they’re probably right in their concerm about weight - a “wet” hydronic installation consists of tubing set into an inch and a half thick layer or mortar. Something to consult with an architecht and/or hydronic installer about.

Electric radiant heat is in the realm of intermediate DIY. Hydronic is definitely advanced DIY at best, and is better left to the pros.

Not sure what their concern is with floating floors. With a hydronic system, the finished product is flat concrete, so they can use pretty much any flooring that’s suitable for installation over concrete. Just nothing involving screws or nails. Ceramic tile is a natural pick, as is resilient vinyl - always popular in kitchens.

About the only possibly poor choice is carpet as it’s going to slow down the transfer of heat from the flooring to the room. Once it’s warm, it’s fine, but it will mean changing the room temperature could be a day-long activity while the temperature stabilizes. Overall, a concern with radiant heat is its speed - it will take some getting used to waiting hours for a room to heat up compared to minutes with a traditional forced air system.

You do not have to embed the hydronic tubing in concrete. We rehabbed our house with hot water radiant and ran the tubing in wooden " tracks" which screw into the subfloor. As for what goes on top,we put engineered bamboo flooring, so I don’t see why a floating floor would be a problem, although tile gives much more efficient heat transfer.

I would not recommend this as a DIY project. Laying out the tubing requires some calculations on heat flow that are probably outside their comfort zone, and will also require a circulator/manifold as well as a dedicated source of hot water. They should talk to a plumbing contractor who has radiant expertise

Interesting, albeit a little late. The project wound up using the Rehau Raupex system of tubes with aluminum plates that hold the tubes and channel the heat. As expected expert help was necessary to plan the heating zones, but it was all dealt with several years ago. Thanks for the input all the same!

Ahahahaha!!! I’ve got to quit sniffing glue while lurking…

After all is said and done, I don’t understand the problem and why radiant heat was even considered. If remodeling to the studs then using forced hot air seems to me to be the simple and least expensive way to go. Although I never did it myself, I’ve seen it done on my daughters house that was flooded out completely on the first floor. Everything was stripped to the studs including parts of the flooring. Running heating ducts was a simple matter.

zombie or no

when a home is stripped to the stubs you can rehabilitate many things. you can treat the house as new construction and do most anything you would do after framing and sheathing.

the below floor radiant system can be added with out deconstruction. the above floor systems can just require replacement of the floor.

kitchens and baths are hard to heat spaces. there is restricted space for radiators or vents, you might need to take special effort and still get less heat than desired. radiant heat is a good solution for those rooms and of desired comfort in the bath.

Yes, even zombies might enjoy having a warm bathroom floor in December.

Radiant heat in the bathrooms is definitely on my list if we ever remodel this place.

True, as far as it goes. But, radiant heat of any type is much more comfortable than scorched air.

I can definitely see the appeal of radiant heat, but still… it seems to me to fall into that category of things that 20 or 30 years down the road causes people to go, “WHAT were they thinking?” What’s the lifespan on the tubing, for instance? If it develops a leak, you must have to destroy the finished floor, the poured concrete pad, and heck, half your heating system. Or suppose the house settles (all the more likely with the weight of the poured concrete) and you get a nice big crack across your floor.

If you look back across the last century or two, it’s these proprietary, innovative technologies that ultimately end up causing the biggest and most expensive headaches for later generations of homeowners. I’m all for sticking to the tried and true.

i have in floor hydronic heat in kitchen and baths placed in wood subfloor material, comes in sheets with grooves cut in it (straight and end of loop sheets).

in basement the in floor hydronic heat was placed on the reinforcement wire that was placed in the concrete floor.

tubing used is PEX, cross-linked polyethylene, which is also used in potable water plumbing and baseboard hydronic heat systems. expected lifetime of 50 years.