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Installing Radiant floor heating in Siberia

debvlad's picture

Hello, newbie poster here, seeking your wisdom.

I am building a home in Siberia, Russia. Actually the frame was already constructed this Fall. I have a full basement (2 ft thick concrete walls with 4 inches of Spray foam on the outside and 1-2 inches on the inside). Basement is 2.7 meters below grade and about .7m above grade. Basement's rough floor right now is 6 inches concrete slab, underneath which is 6 inches of XPS insulation.  Basement seiling/1st level floor is again concrete panels .22 m thick. The actual house is made with 8 inch SIP panels.

I am planning to install water radiant heating in the basement and the first floor. Here is my 1st question: do I need to have another layer of xps insulation on top of the rough floor, before I lay the pipes and pour concrete? Same question for the 1st floor: do I need to lay a layer of insulation before I lay the pipes?

Thank you in advance,


Vlad (post #207500, reply #1 of 10)


Here in Ohio where below zero F. is something they talk about for years.................

we think of it as a place somebody is sent to.


But the questions are interesting and certainly climate oriented.  The answers from me would be the pleasure of living in Ohio with Hydronic, but I think you'd need much more talented info.

I'll contact a radiant designer and specialist-hope he comes by here and discusses with you.


But, here's my thoughts and questions.

Did you isolate the foundation walls from the slabs?

What is the "frost depth"?

While here we put our hose within the slab, and benefit from the mass of the concrete-would it be the same in your climate?  That would help you decide on isolating the heat source from the slab with more foam.


One other system we installed here in our home is something you should take a close look at.  Masonry Heater-ours is a Finnish design with soapstone as the mass.  There are countless designs in these systems, most often from the lands of their use-yours would be what we call here a Russian Heater.  Again, long heat holding-slow dispersing - radiant heat.  Fuel is conserved and clean burning are a big part of this system.

Here's a link to an organization that no doubt has members in your country-



Best of luck in this and Welcome To Breaktime!

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


Thanks, Calvin. the slab in (post #207500, reply #2 of 10)

Thanks, Calvin.

the slab in the basement has just a water barrier from the walls, thermally it is not insulated from the walls. The "slab" that is between basement and 1st floor sits on the basement walls, so again, it is not insulated thermally.

Frost depth is 2 meters.

I planned to lay a reflective layer on top of the existing "slabs", lay metal wire mesh, to which attach water pipe and pour concrete over it to create a new layer of thermal mass which radiates heat. My original questions basically had to do with whether or not it was economical to heat the original slabs in addition to the new ones with the water pipes. If i separate them by installing a layer of XPS, then in theory, more heat will be used for heating the room (rather than original slabs).

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Vlad (post #207500, reply #3 of 10)

I would think you'd want to divorce the two slabs, and with more than a reflective barrier-those are sometimes looked on as being able to do more than they can.  The thicker the foam the better unless you are real short.

But, also remember to divorce the new slab from the side walls-again, with thick foam.


But, I'm in damn tropical Ohio and a dumb carpenter to boot.

I've emailed NRTRob about your question and with hope he'll get to coming by here.  Make sure you check back.  I can't yell loud enough even if I go over the pole............


No kidding, Siberia?  Can you point to the place on a map?  Interesting as all get out.

One more thing-how about that masonry heater?   They use those there?

thanks and the best of luck.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


Siberia (post #207500, reply #6 of 10)

Calvin, we are in Novosibirsk area (an hour south of the city, actually).

Yes, they used to use the masonry heaters all the time here, when people had private homes. Under Communism most people were encouraged to move to Government-owned concrete apartment buildings that are heated with water radiators hung on the wall. There would be a giant boiler supplying heat for 100s of apartments. Energy was cheap, waste was elevated to an art form :)

The reality is - there is a whole different paradigm in Russia. Energy is amazingly cheap (although it is rapidly going up), but the good quality materials (insulation included) and technologies are prohibitively expensive. Also, hiring a "professional" crew to do any work costs the same or double the cost in the US, but the quality is half or less


also, you said "a reflective barrier-those are sometimes looked on as being able to do more than they can."

From what I read, foil reflects only up to 30% of radiant energy (depending on material quality) and radiant energy is 45% of all energy a slab possesses. so maximum benefit of a foil layer is 15 % better DIRECTIONALITY. Some say it is truly insignificant.

Vlad (post #207500, reply #7 of 10)

This truly is an experience.  I don't think I've ever conversed with anyone in Russia.  Thanks for sticking around and chewing the fat.


My education on the foil films/thin backers are that here they are sold as the biggest easiest cheapest way to insulate an attic...................1/4" foam with foil..............

and then this disclaimer-you need to keep it away -not be laminated to anything- to get it's true reflective benefit.

so, against a slab-using that theory, it would be negligable at best.



I don't know the science, but it arose just b/4 the "reflective" insulating paint..................that could reduce your energy bills............


However, a mason friend-the one who is the masonry heater specialist, lived in a house under construction for a long time...................

We visited with them and it was like staying in a baked potato-if you have ever eaten in a restaurant that wraps them in foil.   Bright?   you could lite the whole house with one light bulb.

He then went over it with sheetrock, not sure if he left an air space..................


I'm still trying to get Rob on here to discuss your radiant questions with a little more expertise.


Off to the corner bar for live pizza and good music..........................

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


Interesting (post #207500, reply #8 of 10)

I went to satillite view and saw something I've a question about.

There's some structures staggered with roads/drives up to them.  Looks like the earth is banked around them.

Now here, I'd say that must be a trailer park (due to the layout).  But knowing it's Russia, those aren't by any chance, missle sites?

Just curious..................not wanting to fan the cold war again or anything.


A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


Radient hot water floor insulation. (post #207500, reply #4 of 10)

Radiation and conduction move through 360 degrees.

So yes, you do need insulation below your hot water pipes as 50% of your heat is going downwards.

You need at least 4 inches of a closed cell insulation, like polystyrene.

Like all air based insulation, the heat from your pipes will gradually work its way downwards through the plastic but, there is nothing you can do about this. Of course 10 inches of polystyrene insulation would be better, remember to insulate the edges of the slab to the same level.

The best way to go is to have a light weight radient set up, with the pex pipes set in aluminium plates laying on top of the insulation, this covered with a OSB floor is quicker to heat up and cool down when the sun comes out - it can be very hot up there mid morning and afternoon - trying to loose heat quickly can be a problem.

thank you (post #207500, reply #5 of 10)

Perry525, thanks.

Unfortunately, it is not possible to get aluminum plates here. I am lucky to have PEX tubes :)

Also, on my main (1st) level, I am hesitant to lose 6-10" (basement - no problem - It is over 11 ft!)

 I understand, that if I don't have insulation on 1st level floor - it will heat up the whole slab, but the upside to that is that it will act as a radiant ceiling for the basement. Also, hot air from the basement will be rising to the 1st floor and provide benefit there.

Under existing basement slab I have 6" XPS, so again, I won't be "wasting" a lot of energy, just in the beginning it will take a little longer to heat this slab up.

Can there be TOO MUCH thermal mass? I understand the law of diminishing returns. I guess, the better question is "Is there anything NEGATIVE in having 10.5" radiant concrete slab versus 4" (beside very slow response time)?

As it stands now, the cost for me to add 2" XPS for the entire house will be $1500 or $3000 for the 4" of insulation. Are cost savings significant to offset these costs? How many years will it take to break even? Propane price right now is $508/m3. I consider my house superinsulated.

Thank you in advance,



Concret horrible amount of heat absorbed. (post #207500, reply #9 of 10)

Concrete is a fantastic thing to work with, but it has an enormouse ability to absorbe heat.

If, as I suspect the floor is not insulated from the rest of the building, then in trying to heat the room, you will be throwing masses of heat into the whole building frame, walls, floors - everything! By conduction.

This in turn will be throwing heat into the cold air outside, you will never get the rooms warm.

The idea that a few inches of insulation under the building will make a difference is wrong. The concrete will absorbe all the heat you throw at it, and the heat doesn't float on the surface it disappears into every hidden part.

The only time you will get some of the heat back is when the air temperature drops below the surface level temperature of the concrete.

СПАСИБО (post #207500, reply #10 of 10)

That was "Thank you," by the way.

This is what I am planning to do - keep the Radiant floor temp at 80-90F and the indoor air at 65F