Replies

1. 
   Guest_ | Jun 07, 2000 06:47am | #1

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   Nick, I treat my concrete slab as I would without the radiant heat. It depends entirely what finish you are looking for. Some difficultys you may encounter are screeding over the tubing, but it is not a big one. It is quickly gotten used to. One pour we did had to be done by barrow and we used sheets of ply over the tubing to allow easier travel. Also it is better to not run the heat during your cure to prevent stress cracking near the tubes.

   Alot of my finished slabs are skimmed for the finished floor with Milstone or such topping. But I have also scored the slab into squares, deepened the score-lines and grouted the joint. Which brings us back to the beginning. Just some thoughts.

   walk good david

2. 
   Patrick_Eagan | Jun 07, 2000 02:59pm | #2

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   We do almost exclusively hydronic heat in the mountains of Colorado and David's right treat just as a regular slab. We found pre-blocking our WWM at approximately 1.5" of grade and then strapping the tubing to it works the best. We've gone to pump trucks or chute extensions to avoid damaging the tubing.

3. 
   Guest_ | Jun 10, 2000 07:43am | #3

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   David,

   What is Milstone?

   Jerry

1. 
   Guest_ | Jun 14, 2000 07:27am | #4

   *Jerry, I missed the e, it should spell milestone. It is an acrylic admixture to portland cement which offers many colours and a stable medium to work with on walls, floors, countertops, etc. There are several similar products out there, this is the one I have used the most. An interesting website is http://www.cementics.com. Has a bit of history and some photo examples of what can be done. walk good david

4. 
   Nick_Roberts | Jun 14, 2000 01:14pm | #5

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   So what you are saying David, is that I just pour regular cement and finish it just like a typical basement slab? No special mixtures no added strength? No colour added to the mixture?

5. 
   Guest_ | Jun 15, 2000 07:11am | #6

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   Nick, What I am saying is you finish your slab to suit your
   specifications. Once your hydronics are in place, necessary wire
   mesh, rebar etc and what ever, do your pour as you would if there were
   no hydronics. If coulour is desired in the concrete add it as you
   would a regular pour. If you want to be creative add colour during
   the troweling, do it. The only considerations are, during the pour,
   the tubes are durable but can be damaged through carelessness. And
   you will achieve a better cure if the heat is not on during the curing
   time.

   walk good

6. 
   Dn_Lauer | Jun 17, 2000 06:25am | #7

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   Nick;
   We poured our second story slab using a concrete pumper truck.I initially added my coloring to the concrete truck when it arrived----Bad idea.It would have taken 10 times the coloring we had on hand for the desired color.Luckily the remaining coloring was used by broadcasting it.Even then we ended with a colored surface that was so thin that minor scratches revieled gray because we hadn't enough to broadcast.When using this method to color concrete adhere to the makers recommendations.Also our polyethelene tubing was pressurized after being filled with water.Good luck!

1. 
   Jim_K_ | Jun 17, 2000 12:57pm | #8

   *>Also our polyethelene tubing was pressurized after being filled with waterI'm surprised at this. If the hose was kinked during installation, you couldn't fix it without draining it. Worse, if the tube was punctured, you'd have gallons of water added to your floor or fresh concrete. If it was instead pressurized w/ air, these wouldn't happen. And a puncture would still be obvious. There's no mistaking that sound--I know from experience!!!

7. 
   Guest_ | Jun 18, 2000 07:09am | #9

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   Jim,

   I recently placed my first radiant slab (about 700 sq.ft.) without a hitch. I pressurized the PEX with water before/during the pour but what you said concerning the risks makes perfect sense. I had considered using air, but talked myself out of it. I was concerned about pressure fluctuations due to temperature changes being mistaken for leaks. I was suprised to see this happen with the water. As the PEX warmed during the day the pressure would drop and then rise as it cooled. After placing the concrete the pressure dropped considerably (then remained steady - no leaks) Then slowly rose over the course of a week to where it had been.

   Long explaination - simple questions!

   Have you seen this happen with air? Do you test with water first to find manifold leaks? What pressure do you use?

   Thanks,

   Jerry

8. 
   Jim_K_ | Jun 18, 2000 01:19pm | #10

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   We tested with air mostly be/c we weren't ready to hook up to the
   manifolds or water supply yet. Just daisy-chained the tubes. But my
   HVAC dude gave me the reasoning I passed on above. Set pressure to 20,
   but doesn't much matter. He also tests the system by adding freon (or
   something else, I can't remember) and then using an electronic
   detector.

   As to air leaks being noticeable... While the system was pressurized I
   had to bolt some wall sills to the floor. I must have mis-measured one
   (in my defense--not that I need one :)--it was a curved wall). As my
   helper was drilling, he nicked a tube. The sound was
   unmistakable--PPPSSSSSSSSSSTTTTTTTTTTTTT. Loud and long as the system
   de-pressurized. And when my helper stood up, his face was covered in
   fine concrete dust, like something out of The Three Stooges, only
   there were just two stooges there. Pain in the butt to fix. I'm told
   that if you get a leak during a concrete pour, the effect will be like
   a concrete geyser. Unmistakeable.

   The pressure fluctuations you saw are much smaller than if there were
   a leak, I'd guess. We always pressurized the system the night before,
   so that almost any leak would result in a drop to 0 by morning. With a
   leak of the type that could occur during a pour, the pressure loss
   would almost certainly be fast and furious.

9. 
   Nick_Roberts | Jun 18, 2000 01:20pm | #11

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   With the growing popularity of this type of floor, I was wondering if someone could answer some questions.
   What strength of concrete is ideal?
   Should the colouring be added to the mix or at the trowelling stage?
   How smooth should one expect the trowelling to be?
   Should the concrete be allowed to cure and then be ground and/or polished?
   Should the concrete be sealed while it is being trowelled,or once it has fully cured?
   Anything else I should know?