Need advice on basement concrete overpour

GH

Kevin You could check out our product that you can install yourself. This product has a vapor barrier shell
and is water proof with extreme light weight high PSI concrete. If the floor gets wet as some basements have
been known to do this product will not go into self destruct. This product also fixtures the tube as you install
and you can find your tube and or make changes in lay out if you like . So check it out www.GCSRADIANT.com

kevin_5

concrete overpour

This may be a concrete question more than a heating question, but I know I'm still in the right place, as some of you have probobly done this many times.

I just finished a couple homeshows, and have several people interested in doing their basements. (too bad they already poured them)
The cost of Quick-Trak seems prohibitive, and in the basement I'd have to first put down 47 sheets of 1/2" plywood to screw the quick trak to.
Talk about extra time and materials!

The question is, how have you done this?
We don't have anyone very close who can do the gyp-crete lightweight stuff, so I'm thinking regular concrete, and weight is not an issue here anyhow.
All I know is Wirsbo wants 3/4" of pour over the tube.

What is the thinnest pour you can safely use with regular concrete? Is there a special mix to recommend?

Is it safe to put down 1/4" of the bubble/foil/bubble insulation under it?

Since the foam staples won't penetrate on such thin insulation when it's directly over concrete, what attachment method do you use? Is pex/al/pex part of the answer? I know foam would work, but it's quite a bit thicker, and I sure like the idea of the foil radiant barrier if it's workable.

I know it's not my job to tell people what they can and can't afford, but it sure seems the overpour would be a lot more cost effective. Am I missing anything? Thanks to you all in advance. (You've never disappointed me yet!) Kevin

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ta finnegan

Thoughts

Have you looked at the Watts Base Ray product. Nice for retofits when a staple up is not an option. I like the Onix tubing for this.

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Chris Maderia

How about this for a possible solution

Use R-Foil bubble wrap for your insulation over the exisiting concrete. Use 1x6 Firing strips or in the attachements photos 1 x 12's with a 1" space inbetween them and shoot them into the concrete. Then use transfer plates as in the photos or better yet Radianat Engneerings Thermo Fin plates (They come 8' long). You can then apply your finsished floor and you've made your own quik trak. I've attached pictures of job that I recently designed for a contractor. Bye the way, nice job Frank.

Unknown

some people have had some success using chicken wire to tie to the tubing down to.

for concrete pours you want at least 1" of concrete over the top of the tubing, so for 1/2" tubing you are looking at 1.5" concrete pour minimum.

Unless you know for certain that the existing slab is insulated underneath, also use some kind of insulation between the two. I would personally go with a rigid foam, but bubble insulation will provide at least a minimal heat break if it's rated for under-concrete usage.

kevin_5

Is OSB Okay, or must I use plywood?

I like your idea Chris, and the homeowner has indicated he would like to help with labor to keep costs down which is fine with me, but he wondered if OSB (oriented strand board, like they use on roofs a lot)would be OK. I see no problem with it. It handles extremely high temps on roofs, but I need your experience to speak to me here.

I planned on using 5/8" board, and 1/2" tubing, with plates, and 1/8" foil/foam underneath. My wife was going to run a heat loss on it and see what we need. Any problems with running the plates and tubing 16" on center if it will handle the load? It might help cut the cost a bit.

One more question, IF we did an over pour, what about cracking? The homeowner has done quite a bit of concrete work, and can't believe it would hold up without cracking.
I told him I didn't know, but I knew the guys who had done it before, and would find out. Thanks again for all your help. I would really like to see this young couple have a radiant basement, and it would help me too if I had a more cost effective method than the quik trak. Kevin

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Dan Peel

Floor system

If you stray too far from "normal values" you'll end up with nothing of value. I'm all for lowering pricing to the customer when the application allows but, from your suggestions so far you're begging disaster.
In a heatloss program you may be able to input a high enough water temp to get a result on 16" ctrs. - that won't make it work well. The closer to the surface of your finished floor you place the tubing the more striping you set yourself up for - 12" is typical spacing in embedded systems with a couple of inches of concrete to help blend the surface temperature. Delivering to a heat loss can only be achieved using an average temperature across the panel area. Look at 8" spacing with plates, 6" spacing without. 16" spacing is right off the map. For materials savings choose 1/2" plywood and 3/8" tubing. Tubing is cheaper than fuel and you only have to buy it once. Enjoy....Dan

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Steve Eayrs

watch the heat loss

I don't know where you live, but up here in Alaska, where the ground temps are real low in winter, and not that high in the summer, you could have problems.
Even if you insulate under the slab, (and I will not do a radiant system unless they will), the perimeter edge has a a huge potential for heat loss. Very high if the walls are concrete or concrete block. Seen a couple places where they could just about grow flowers around the house all year. 1-1/2" high density foam could be used, and still use the foam staples, and if moisture is a problem than, you may not want radiant floor unless that problem can be solved. water is great conductor of heat, and can turn good insulation into a condutor.
Steve

Of course maybe a 1' wide snow melt system all around the house is desired........

kevin_5

Thanks guys

I appreciate all the adivice. I will let you know what I come up with.
Incidentally all your advice makes a lot of sense to me. Don't you feel better about giving advice when people actually TAKE it.(especially when they asked you)
I will let you know what I come up with. Kevin

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