Slab shield R-values

Chap

Verbal Diarrhea Deniability

Nothing in writing. Seems like the SWAG stuff is always verbal. My first question was "why the range?" Kinda like being half-pregnant! R-10 if it's damp & R-14 if'n it's dry? Gimme the why's & where for's or get thee out the doors!

Chap

10 to 14 R-value?

Customer says the mfgr claims R-10 to 14. Anyone have info???

Rich L.

No experience but...

Hi Dave, I don't have experience with this stuff but checking them out on the web I found this claim in thier advertisment:

"This is where the pure aluminum center-leaf comes into effect. It provides an effective thermal-break between the foam layers and prevents the slab or heating system from seeking the cold ground below it,"

They are claiming that a layer of aluminum in the center is going to stop the heat flow from the warm slab to the cold ground. Huh? Since when did aluminum not transfer heat? Sounds a little like some of the bubble-foil-bubble claims over the years.

The web site this comes from is:

http://www.heatall.com/radiant/slab_shield.html

Till something better comes along I'll stick with the 2" pink or blue stuff!

Regards, Rich L

John F

Their literature says R-2.9.

Chap

Thanks!

That's exactly what I needed. Some slick salesdude was spoon-feeding them R-10 to R-14. I suggested it was much lower, but the HO's wanted to hold onto that higher R-value belief. Nice to hear it straight from the horse's mouth(G).

Unknown

someone should let that sales guy know that he's committing fraud?

Don Regan

Crete-Heat...

is what we use on all our underslab radiant installs.

Kevin O. Pulver_2

Dave,

We've used a lot of this slab shield and like it.
Nebraska wind has a fit with the foam board.
This stuff conforms to the ground and doesn't break up when you walk on it. A basement would be one thing, (down out of the wind) but a large slab on grade is a nightmare around here. I use duct tape on the seams. Even sticks pretty well in the rain!
Kevin

Unknown

if you have to use a roll/tarp product, use "the barrier". it's the only one with a real R-value.

no offense, but slab shield is not insulation.

Rob Blair

Rob,

I just went on the barrier webpage and they stated 1.7 R for 3/8" and 3.4 R for 3/4". Slab shield is 2.9 for 1/2". How can you say that it doesn't have any r-value?

Rob

Unknown

slab shield is including the dirt, gravel, concrete, and other non-slab shield components of the assembly in that number. See the note about "testing in a concrete assembly"? that's what it means.

Slab shield ITSELF not 2.9 and statements to that effect are at best misleading and at worst a violation of the FTC R value rule. Since other companies have been bitten by the FTC already, I imagine it's just misleading if you were to compare it to other insulation products NOT tested in a concrete assembly that state just their 'naked' Rvalue.

Again in this thread, go here for all the reading you want; http://www.healthyheating.com/Page 55/Page_55_o_bldg_sys.htm

In short, study after study after study proves, the performance of these products is more like a 1.6 to a 1.8. That may not seem very far away from the R2.9 claim, but it represents a nearly 50% reduction in effectiveness. Technically yes, that's an R value. It is, however, a colossal waste of money if stopping heat transfer is actually your goal.

The barrier is foam. that's it. 3/4" of R5/inch foam is R3.75 and the barrier is slightly less than a true 3/4" thickness of foam, due to the extra layers on it. But it's nothing magic, just rollable foam.

I wouldn't use that either because it's not the 2" of foam I like to see in most cases, but if I had to use a tarp/roll product, I'd use ONLY it. All bubble/foil or reflective tarps are junk. all of them. period.