Things I like to hear from my customers...

[K Frame]

"then a lecture on the forensic investigation at Little Big Horn..."

We expect a FULL report on that in another thread!


As long as your sub base is properly prepared and the correct styrofoam board is used I don't see how the slab would be any more prone to cracking than when using any other type of insulation.

Compaction of the sub base is absolutely crucial to maintaining the integrity of the slab, no matter how it's poured.

My only concern with insultarp is...

Have any independent studies been done on how much effectiveness it loses due to the compressive weight of the slab on it?

[280plus]

Good question, I believe the R-10.5 rating applies to it when compacted. That I'd have to double check. I like the tarp because if the sub base is ueven the tarp just follows the contour. I also question how much the styrofoam is compacted as well. To me, the tarp just seems easier I guess, all you have to do is roll it out. Plus, it is what my distributor recommends.

I'll check on the R value thing.

[280plus]

here's what I got off of Google, theres plenty more there too...

http://www.radiantmax.com/insul-tarp.html

[K Frame]

The styrofoams that are recommended for underslab use show virtually no short or long-term compaction. They're very rigid and are almost structural in their own right. The way they're installed also greatly increases their ability to bear weight without compacting.

Think of it this way...

The slab and the panels are dimensionally very close to the same size -- that means that the entire surface of the styrofoam is bearing the weight of the slab, giving an extremely low pounds per square inch value on the styrofoam.

It's like when you go out on thin ice... if you're standing, all of your weight is concentrated on your feet, and you'll crack the ice surface. If, however, you lay down, the ice can support you because your entire weight is being supported by a much greater area of ice.

Granted, the installation of panels is much fussier than the tarps because the subsurface has to be very flat and very well compacted. With the tarp, you don't have to spend nearly as much time leveling the surface -- it still has to be highly compacted, though. If it moves, the slab is going to crack.

Don't get me wrong, I'm not advocating one against the other. I can certainly see advantages to the tarp, if it works as advertised.


Hum... In reading through the Insultarp information it's being a bit disingenuous... It gives the impression that there's no under-slab foamboard on the market that can mitigate radiant heat loss. That's a lot of "hot air" so to speak. Slab-Shield is but one of the faced under slab products on the market.


Oh SNAP!

Check out the letter from the Federal Trade Commission on this website: http://www.thebarrierinsulation.com/7128.html?*session*id*key*=*session*id*val*

"...it may be misleading for industry members to suggest that such foil products will reflect radiant heat when installed under concrete.

Interesting. And the underlining is in the letter...

[280plus]

Yea, this stuff has no aluminum foil, the reflective cover is actually ripstop nylon too but does seem to have a metallic coating on the inside of both layers of nylon. But it's not just one layer of foam between. I have a scrap here and I count 6 thin layers of styrofoam sheet and 1 layer of bubble wrap. So there's plenty going on in there. I think the same thing holds true on compaction the tarp is able to support the whole weight of the slab without crushing because it is spread out. It seems to work. 

Oh, actually not too much exciting stuff at the lecture. The interesting part was the Cavalry only had 2 weapons, the 1873 Springfield trapdoor carbine and some kind of Colt pistol, I can't recall what it was exactly. Turns out the Injuns had no less that 47 different kinds of firearms from all types of cap and ball to the 1876 Winchester repeaters which were the cutting edge of the technology at that time. The Guy (Dr Douglas Scott BTW) says MOST of the weapons used by BOTH sides in the battle came from CT and Springfield Mass. They actually located lots of empty brass and through the magic of ballistics were able to determine which rounds were fired in which gun and how that gun made it's way around the battlefield. Short lecture but informative. The ratio was 210 soldiers to 1500 indians. Not very good odds I'd say.