Am I going to gain a better R value with an 8" concrete pour vs a 6"? How about the EPS thickness? I notice that most manufacturers are making 2-1/2" +/- per side thicknesses. Quad-Lock offers a few 'thicker' panels. Will the 'thicker' EPS panels actually give me a better R rating, or is that hype? This house will be built in a very environmental area... no neighbor is going to want me to pollute the area with tiny pieces of styrofoam - blown everywhere. Can you give me some ideas of what you do/use to contain as much of the cut waste as possible? I've watched a number of videos that show the stuff blowing everywhere - which will get me shot. Suggestions?

More EPS adds R value, more concrete has little effect. To avoid EPS dust, you can cut with a hot wire.

As it was explained to me by a well known energy guru, EPS a 1.5 psf and 2" thickness is efficient, exceeding those perimeters is a waste of money. We use thicker EPS because of concrete pressure it exerts and the current thickness is what works with minimal additional bracing and support during the pour. Our current building codes are still basing evaluations on resistance value and not heat transfer value.

Posted By Roger R on 30 Jun 2013 04:49 PM
Am I going to gain a better R value with an 8" concrete pour vs a 6"? How about the EPS thickness? I notice that most manufacturers are making 2-1/2" +/- per side thicknesses. Quad-Lock offers a few 'thicker' panels. Will the 'thicker' EPS panels actually give me a better R rating, or is that hype? This house will be built in a very environmental area... no neighbor is going to want me to pollute the area with tiny pieces of styrofoam - blown everywhere. Can you give me some ideas of what you do/use to contain as much of the cut waste as possible? I've watched a number of videos that show the stuff blowing everywhere - which will get me shot. Suggestions?

Roger - while other on this forum may disagree, I don't believe you need to increase the thickness of the eps. The trick is to keep all the concrete encapsulated in the foam. The thickness of the concrete will not matter much unless you are doing some special heat storage design and then I think there is better places to do it than the walls.
If you cut your foam with an abrasive blade rather than a tooth blade the foam will melt and not scatter.

If you are using a plank type form like Quad-Lock or LiteForm (what I used), you can cut the EPS planks to the desired length with a 14" chop saw with concrete cutting abrasive blade. This blade essentially melts through the foam cauterizing the cut and you don't have any styrofoam beads floating around. You will get some thin strings of melted EPS spit off the blade similar to spider webs that are easily collected and disposed of.

Here is a link to Quad-Lock's web page stating their R Values per EPS thickness. http://www.quadlock.com/images/icf_components/R-Values/ICF_Walls_R-Values.png Does this look accurate?