Self installed concrete floor?

heaterman said:

Sand is a better medium for insulating than conducting. They make firebrick out of the stuff........??? just sayin.........

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They make rockwool from rock and fiberglass from glass (sand).......but the original rock and glass are terrible insulators.

It's not the material, but the form it is in........which often creates the insulation. In these cases, it is often the air which does the insulating.

As to thermal mass, it always depends......if there is somewhere else for the heat to go! If a mass of floor is over wood framing within the envelope of a house, it would seem that the heat must either go into the home or back to the boiler (return water, etc).......

But when concrete is poured over earth, it might lose a lot of heat to the ground....etc.

I think part of the rule of thermodynamics is that it has to go somewhere......mass can even out the transfer (like soapstone).

Walk on the hot beach sand in the summer. It makes you skip all the way into the water.

Move about 2" off the top and feel the temp difference.

Maybe Michigan sand is different

Heaterman gave you an excellent link to check out....please do so. If that particular product is not available in your area there are many others that all fit into the low weight high comfort category. No good reason not to use some of the best designed products on the market. The cost relative to the risk you may have been considering makes it a no brainer.

We just left a job that was a gypcrete over pour (designed & engineered) it had TJI trusses at 6" O.C. Yup thats right you can.....just get a 4" toilet flange to fit in between & I do mean....just. Gives you an idea of how much more weight this process ads.

In a residential setting products like Heaterman mentioned are the better way to go.

Extremebison said:

As far as how the floor is built of I'll have to tear up the thing and just see. The house was built in 2000. But this is the Yukon you never know what one will find. It is the ground level floor, I can't get under it to see as the logs go right to the foundation. One would think it's built to code, but I already have problems with the septic, and I ask who approved it and I get sent in circles and told I'm on my own. Also I replaced the outside lights with motion lights and found the connections were made with vapor barrier tape, so much for a electrical inspection. So who knows how the floor is built.

Thanks for all your help

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If you cant get at it anywhere , it might be slab on grade. It might say on the listings papers when your house was for sale .
When you buy a house the listing should say slab on grade , basement ,crawl space etc. Try to find a spot where your plumbing comes up. like under your kitchen sinks wheree your drain goes through the floor. Or rip some floor up in a closet.

Here’s another option that works extremely well. In fact my bare feet are resting on it right now as I sit in my chair. No weight or structural concerns, only adds 1/2†in height to the floor, very even heat, water temp requirements are nearly as low as gyp or concrete.

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Wow what a great product! Is it expensive?

After reading all of this thread again, I think the concrete option would not be the one I would choose. I think the climate panel heaterman suggested is a great alternative. I didnt know this was out there.
If you just have to have some thermal mass the plywood strips with thinset and 1/2" concrete board is another great idea, one that after doing some quick math is really affordable, would be only 1 1/4" thick and would not add anywhere near the weight to your floor.
I like this idea the most, as you could get all the material at any lumber store. Aint this a great forum.
good luck

heaterman said:

I'm seeing some things and suggestions here that are making me nervous..........


Here's another option that works extremely well. In fact my bare feet are resting on it right now as I sit in my chair. No weight or structural concerns, only adds 1/2" in height to the floor, very even heat, water temp requirements are nearly as low as gyp or concrete. Response time to heat input is about as good as you can get with a radiant floor. Off the cuff I'd say it's probably 4-5 times as quick as a thin pour.

here's a blurb http://www.ebuild.com/articles/1211498.hwx

here's the whole 12 minute video http://www.viega.net/productcatalog.html#model-group284639617504

We have put down literally tens of thousands of sq ft of this product. It works and works well.

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When this stuff is used do you put down anything else for insulation under the floor?

What about on a basement slab, would it work on a basement floor that does not have foam under concrete?

What have you found to be the lowest useful water temp?

gg

Is there a reason that it needs to be an in-floor system? From what I've gradually osmosed over time here in the Boiler Room- if I were working from a clean slate, I'd probably go with euro-type panel radiators-- they'll respond much more quickly than a floor, and are much less material and labor intensive, especially if fitting into existing construction.

I wouldnt pour on anything if I didnt know what was under it. Lots of suggestions and nobody even knows whats holding the floor up.

I don't have anywhere near the experience some of you guys have, but I'll tell you what I've gotten away with so far.

I converted a barn with 2x8 floor joists, added additional beams to reduce the span and poured 1 1/2"- 2" of concrete/limecrete mix over pex, then tiled it. I also poured an 1 1/2" concrete slab over a 13x22 floor and tiled it with granite. The granite developed a hairline crack that is only visible if you know where to look, this was over a cold joint in the pour.

It was a lot of work but I'm very happy with the result. Just came home after three days with no sun and temps 5-25 and it's 64 inside.

The weight is not that big of an issue to deal with, especially over a crawl space. You have to add some beams and posts, but there is a way to do that if you want to.

"is the mass that important" ask anyone who has burned wood with storage (mass) and without it how important it is. Sure you could build a shed and buy some propane tanks to store the heat, but the floor will do the same thing without the complexity. Of course the complexity also gives you control that you don't have with storing the heat in the floor.

If you're feeling adventurous look up "screed floor" on google or youtube and see how the europeans do things.

I'm not saying any of this is worth the effort, especially with a newer house, but if that's what you want then go for it.

Thermal mass be it a tank of water or a concrete slab cannot create energy or heat, It's just a flywheel.

In some, many, cases it is an asset to a radiant system as it can help dampen wide temperature swings. But you still need to put energy into it and keep putting energy into in proportion to what it loses to the room and any loss down or out the edge.

In some cases where you have wide and sudden outdoor temperature swings, or maybe a lot of passive gain, a high mass system can cause some overheating. It takes a while for that flywheel to wind down when you have it filled with thermal energy. The more mass you have the slower the response.

Using a control to keep the slab at the exact temperature to meet the load helps with high mass. An outdoor reset control helps adjust that input temperature to the slab and prevents overshooting. Of course it adds more cost and complexity.

It always comes down to the individual application and your expectations. Read some of the homeowner reviews on those high mass sandbed system. In the shoulder season, the fall for example when the slab is charged up, but the outdoor temperatures are still mild, opening and closing windows is the only "temperature control" they have. Using open windows to control an overloaded warm floor is not for everyone.

hr

benjamin said:

I don't have anywhere near the experience some of you guys have, but I'll tell you what I've gotten away with so far.

I converted a barn with 2x8 floor joists, added additional beams to reduce the span and poured 1 1/2"- 2" of concrete/limecrete mix over pex, then tiled it. I also poured an 1 1/2" concrete slab over a 13x22 floor and tiled it with granite. The granite developed a hairline crack that is only visible if you know where to look, this was over a cold joint in the pour.

It was a lot of work but I'm very happy with the result. Just came home after three days with no sun and temps 5-25 and it's 64 inside.

The weight is not that big of an issue to deal with, especially over a crawl space. You have to add some beams and posts, but there is a way to do that if you want to.

"is the mass that important" ask anyone who has burned wood with storage (mass) and without it how important it is. Sure you could build a shed and buy some propane tanks to store the heat, but the floor will do the same thing without the complexity. Of course the complexity also gives you control that you don't have with storing the heat in the floor.

If you're feeling adventurous look up "screed floor" on google or youtube and see how the europeans do things.

I'm not saying any of this is worth the effort, especially with a newer house, but if that's what you want then go for it.

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Not only is thermal mass important but where it is is and how much is also important. I would rather have my thermal mass in the storage tank than in the floor. Even with my relatively low mass 2 1/4 thick floors with staple-up I frequently overshoot my temperature setting on the wall thermostat because the floor is emitting so much heat after the thermostat has been satisfied. On the other hand it often lag when the thermostat calls for heat (response!!). My mudroom floor is very responsive with the cement board/tile sandwich.

I've tried both high and low mass. In my shop it make sense to have the radiant in the slab, exact temperature control is not that important. In the house I went with plates under the wood floor and some radiant ceiling. In that application I would rather the thermal "battery" be in the buffer tank. With low mass, especially a dry system with plates you can accelerate and decelerate quickly. So it allows for quick setback as we leave the house at 7AM and return about 6-7 every evening. i can set back to 65 and within 15- 20 minutes feel warm when the floor and ceiling start warming up.

On my next remodel a blend of floor radiant in the tile bed and panel radiators will be my choice.

The current issue of Solar Today magazine has an article on sand bed radiant storage., "Storing Summer Heat for Winter" I like the method they used by insulating completely around the sand bed. Then a second installation of radiant tube on top. Now they have the ability to pull the heat when it is needed.

www.solartoday-digital.org/solartoday/20110102/#pg28

hr

I agree with everything Fred and HR have said, but it comes down to what you're trying to achieve. An automatic system is nice, but most of us are still going to be throwing the wood on the fire.

As HR warned, I got caught with a roaring fire and the sun coming out unexpectedly on Sunday, if 84 degrees in January is considered a failure, then I can live with that. I can get away with a range of 60-80 degrees, even 58 or 90 once in a while, so the mass in the floors and walls adds a small buffer that smooths the wood heat and solar gain over a day or two.

The sand bed system is an interesting idea. The "summer heat" title was somewhat misleading, they didn't mention what percentage of the heat was stored from summer and what percentage was stored a few days or weeks. If you really want to store summer heat look at Annualized Geo Solar or Passive Annual Heat Storage, they have ideas in use for storing much larger amounts of solar heat from season to season. I haven't seen a sand bed hooked up to a wood boiler but it makes a whole lot of sense to me.

Back to the original post, I can't see the project being worthwhile in such a new house, but it definitely can be done and can make wood burning much easier to manage. Another similar option is a masonry heater. I've heard they are even harder to get the time lag just right, they take a long time to heat up and can then overshoot the temperature. You could build your own version to match your requirements. If you're considering pouring your own concrete floors over wood then I'll assume you're the type who's not afraid to experiment a little with a super sized Russian oven.