lots of products out there.  have been reading the forum on the warmboard product.  seems that everyone swears by it, but the stuff seem pretty pricey.  i have a finished basement with carpet.  i am pulling up the carpet and want to put down tile, but before i do that i want to consider installing radiant heating.  with the warmboard product it seems like i am paying for a subfloor along with the grooves/aluminum for the piping even though i don't need the subfloor (i already have a concrete floor).  is there any product out there that functions as well as the warmboard, but is designed for my needs?  thanks for the help. 

john

Is the floor insulated? or do you need to insulate before puuting down radiant tubes?

not sure. if i had to guess i would say it is NOT insulated. the house is 102 yrs old. i was expecting to insulate on top of the slab that is there now. am i correct?

Yes you will need to insulate before laying tubes. Your easiest is blueboard, tubes then concrete.
There is a product that combines insultion and tube layout but not sure about the cost.( look at other posts fot the product)
I would not go warmboard in this sitution.

The BARRIER is the Best tho! insulates, is a moisture barrier and will not break !

I was hoping on doing this myself and the thought of pouring concrete will definitely put an end to my DIY spirit. Any thoughts on doing this without pouring a concrete slab on top of the tubes? is this possible?

Roth panel; insulation and aluminum in one panel. It's made for this. 3/4" or 1" height buildup then tile.

if you don't already have a hydronic system though and don't plan to do more with it, and this is a small area, you might consider electric radiant as well. As an option. Not knowing what else you're doing it's hard to say what would make the most sense.

thanks for the info rob. right now my wife and i are just getting started. we have a basement that has carpet covering 80% of the floor which we have to remove and replace (we want to go back with tile due to my wife's allergy concerns) that being said we want to go ahead and install a hydronic system, mainly with the thought of one day having all 800sq feet of the basement heated this way. as for the rest of the house, i don't think we would ever do it, but you never know. i always thought electric would be more expensive. also, at some point i would like to have the system connected to a solar collector on the roof which would provide domestic hot water as well. what are the pros and cons for hydronic vs electric for 800 square feet?

depends on your electric rates ;)

But really, that's a pretty small area for a separate hydronic system (though "radiant creep" into other areas of the home does happen too). I'd recommend looking at both options so you can make a fully informed choice though, as you may be in a situation where electric makes sense.

I just talked to the folks at Houseneeds.com and they said you should always insulate under the slab. 6 mil poly with 2 inch blue or pink board over that...then pour.  Pex should be in the center of the slab.

Hope this helps

 

You can also use THE BARRIER, it has the benefits of poly and many of the benefits of 2 inch blue board in 1 product! ALSO a 100% moisture resistant, vapor, radon etc. YOU should always insulate the SLAB. Please see LINK before you do anything. Educate first. SHipped factory direct to you. contact us at link

Is it anywhere near 2" thick? If not there's no way it can provide the thermal resistance of 2" blue board.

I decided to take a look at the web site you link to. In the description for "The Barrier" I find this sentence. "It's common knowledge that R-Value refers to a materials ability to resist the flow of hot or cold air from one environment to another. The key aspect of this is the direct reference to "resisting the flow of air."

WHAT A CROCK that statement is!

Here's what the DOE says about R-value in their publication "Insulation Fact Sheet." "Insulation is rated in terms of thermal resistance, called R-value, which indicates the resistance to heat flow. The higher the R-value, the greater the insulating effectiveness." R-value has NOTHING to do with air flow.

In the description of "The Barrier" they say, "The test data results are that The Barrier has a K-Value of .6 per 3/8". When you take the units for K value and convert the .6 per 3/8" into R value we come up with an R value of 4.44 per inch, which is about the value for EPS. The 3/8" thickness has an R value of 1.66, way less than is generally recommended for under slab insulation for radiant heating.

Why aren't there any ICC-ES reports on The Barrier or other products from Barrett Enterprises?

Take a look at Crete-Heat. No Smoke & Mirrors.

I went to the mfr web site. The info there is more straightforward and honest than the Barret Enterprises web site. The Barrier does look interesting.

Trying to distinquish between R value and K value is simply trying to avoid discussing the value most people are acquainted with because it is such a low value. R =1/K, K=1/R. Thermal conductance is the reciprocal of thermal resistance. Two ways of describing the same exact physical property.

But even the mfr obscures the insulation value by advertising an R value of 4, but at least they admit that is for the entire assembly of concrete, barrier, and sand and gravel. The small print does say the R value of the barrier is 1.7. Dry sand is a good insulator. In old days blacksmith shops used forges constructed of a wood box filled with sand. 2" or 3" of sand would keep a hot fire from burning the wood!

There's no question that The Barrier has value, but don't try to sell it as being equivalent to 2" of XPS in thermal conductance. It ain't. After all, it's K-value is about .1 for 2" compared to The Barrier at .6 for 3/8". Adjust either one so you can compare equal thicknesses and they are almost the same. Add a sealed vapor barrier over dry sand under 2" XPS and you'll have the same additional benefit The Barrier touts.

This is really getting old.

K-value is simply conductivity. R-value is resistance to heat flow, and is simply the inverse of k-value. To say that K-value matters, and R-value does not, is absolutely ludicrous. You really need to stop believing everything you read in the product's marketing lit. That's flat out wrong, using non-standard figures for K-value to mislead even professional consumers (K-value is usually a figure based on a one inch thickness).

The Barrier is EPS foam. a 1/2" "The Barrier" gives you the same R-value as 1/2" of EPS foam, ditto for the thicker version. It's not magic, and suddenly adding in sand, gravel and the resistance of some concrete itself which is present whether you use the barrier or not does not make it better than equivalent thickness of EPS.

R4 and R5 are NOT extremely impressive, even if you want to give your product the charity of adding in those other layers (which is like adding in siding and air films to a wall insulation product to make it look good, and is ILLEGAL when marketing insulation, I might add, but hey, why quibble) They are substandard R-values in most regions of our country, though they are better than nothing. A typical R-value spec is for R10 (insulation only R-value). The Barrier is definitely better than the reflective foils

EPS foam holds its R-value when wet, last I knew. water permeability is not the issue. Even if it were, any residential slab these days should have a polyethylene barrier under it which renders that point fairly moot. The Barrier saves you a step, but it saves you a step at the cost of cutting your target R-value drastically. Another way to say it, is that it more than doubles your slab heat loss compared to 2" of rigid foam... quadruples for the 1/2" product. Now it's still not necessarily gigantic numbers, but it's real money over time. That's "Green"? Really?

I am not sure how you plan to "educated and promote green products" when you don't understand the first thing about the products you sell (as witnessed by practically all of your posts on this forum) and purport to be 'educating' people about. Perhaps you should stop trying to "educate" so much, and instead work on your own education. You had the reflective foil under slab breakthrough, so I have hope you may continue on the righteous path.

Here is your arguement for the barrier: you don't always need 2" of rigid foam. If a lesser amount of insulation is appropriate due to mild climate, exceptionally dry and sandy soil conditions, for very large slab CENTERS (not edges or perimeters), or for periodic use like snowmelt, "The Barrier" can be a fine choice.

But it is in no way, shape, or form equivalent to 2" of rigid foam. To even insinuate that it is, is either fraudulent, or based in ignorance. I assume the latter here, for you, though I can't say the same for the MFG, I believe they have already been ordered to stop using the K-value arguement in the lawsuit they settled with the FTC earlier this year: LINK

I just noticed another thing about the Barrier installation instructions and NOFP sales pitch. NOFP discusses the need the prevent water vapor from coming through the barrier because water can degrade the insulative value of the assembly and that is a major drawback of foam boards. Interestingly though, the install instructions have the installer place the taped overlap on the TOP SIDE of the barrier. What that does is leaves all the seams open on the underside. Vapor from the ground can eventually permeate the barrier decreasing its effectiveness. They should have the taped seam on the underside of the barrier.

Did not realize this was a place for personal complaints so this will be last post here but wanted to set the record straight about one very important thing that someone has said that is not at all correct. We have never advocated the use of reflective foil products under slabs ! Never ! I also am a distributor for outdoor wood furnaces and I will not use foil in our underground water lines so this is not a correct statement at all.

Barrier is taped underside when applied properly.

I do have to apologize. I could have sworn we'd been discussing under slab radiant barriers, and I can't seem to find those conversations. So I have to assume I am a little crazy there.

That does not let you off the hook for parroting the stuff The Barrier people got sued for, so if that qualifies as a "personal complaint" so be it.