I wish that builders and homeowner in my area were more progressive and see value in additional insulation, such as 1.5" XPS or iso, but that is not the case. 95% of homes that I see are concrete foundations (often left completely uninsulated, since they are spec homes built cheap and the developer does not have to worry about heating the home) with 2x6 walls above with fiberglass batt insulation. Only when there is a total shift in values and homeowners see these types of ungrades as INVESTMENTS rather than COSTS (whether it be ICF, geothermal, solar, etc) will the construction industry see any changes.

I apologize for getting this thread off track. I didn't mean to ruffle so many feathers. I have been in the construction industry for 11 years and working with ICF for about 4 - it is a technology I believe has numerous advantages as a builder and as a homeowner. I have reaseached ICF quite extensively and am still learning more every day. I am simply trying to make this case based on data I have found.

Posted By Ray Gladstone on 16 Aug 2011 03:19 PM
"The most typical new construction I see near me is 2x6 + 1-1.5" of XPS or iso, which has thermal performance quite comparable to R22-R26 ICF"

I think you might be makin' that up.

It's not me, the folks at Oak Ridge Nat'l Labs are makin' that up- I'm just a sucker for their data. (Seriously?!). 

Whole wall R of a blown-fiber insulated 2x6 studwall is about R14-R15, depending on stud-spacing & other framing factors and to some extent the fiber density. An inch of exterior foam puts it in the R20 range. With 1.5" of iso it's in the R25 range.

The mass effects of the concrete are often overstated in the marketing of ICF- according to ORNL data it only hits double-digit energy-use savings over low-mass construction in local climates with truly huge diurnal daily temperature swings.  (And stick-built isn't necessarily low-mass- putting the mass fully inside the thermal boundary has a modest performance advantage over insulation/concrete/insulation stackups.)

Or mayhaps you're suggesting that in my neighborhood they don't actually build that way?

R13 + 5 is still legal as far as MA state code, but most local builders are going R19 + 6 or 7.5, even on spec-housing.  In this climate zone R19 + 7.5 is sufficient to dispense with interior vapor retarders (per the IRC), and that's pretty typical of how mid-range houses are built here. I haven't looked at any low-end spec houses lately- could be there are some going R20-no-foam (which is also bare-minimum per state code and has whole-wall R of ~R15).   Better-builders locally are using blown fiber and R10 sheathing. 

Code-min on foundation walls is R10/13 here, but still see a lot of post-pour insulating of foundations rather than ICF. I don't see how they're actually saving anything that way- a minimalist- R16 ICF approach isn't very expensive, and has advantages for the builder beyond just the ~35% reduction in heat loss out of the foundation.

I kind of feel like I'm interrupting but...

I guess we're going to go with ICF foundation. My builder says it would only be $1 - 3/sq ft cheaper for a poured foundation and then we would have to frame and insulate.

ICFhybrid - re: root cellar, is there some reason to use ICF walls for the root cellar instead of insulating walls? Just out of curiousity, can you tell me anymore about your root cellar - how big, what are you using on the walls, do you have a window in there, ... Thanks for any info.

Everybody else - just continue your discussion, it's very interesting.

I'd like to see any pricing comparison for:

1) ICF basement with wallboard
2) Poured basement + exterior foam
3) Poured basement + wallboard and interior insulation
3) FPSF monolithic slab with a fully exposed, wallboard+wood+foam+siding "basement/garage"

Say all at the same R value or thermal performance.

No window in the root cellar. In fact, the door will be well sealed to prevent light from getting in under it.

Don't want the vegetables stored there to get any funny ideas from the light. :-)

It is long and narrow with shelves along either side deep enough for bins. (18' X 10')

Floor is concrete slab, not insulated.

We needed well insulated walls because the storage areas shared the basement with living areas. We wanted the wine cellar, root cellar and storage rooms to have cool, constant temperatures, while the other living areas would be warm.

Designing interior basement walls of ICF helped strengthen the entire build and kept us at 6" ICF forms instead of 8". I was worried because some contractors called the additional corners "more complex", but it turned out that they were no additional trouble during the build. I am glad we used them instead of insulated frame walls which would have been yet another construction step.

Right now, the insuldeck ceiling of the root cellar is open to direct sun and the upper slab temperatures have been in excess of 100F. Because there are no doors yet, the basement is open to daytime temperatures of 75F and the root cellar still maintains a slab temp of 55F and an ambient temp of about 60F. I think we are on track for a finished target temp of about 57F.

From above:

"The mass effects of the concrete are often overstated in the marketing of ICF- according to ORNL data it only hits double-digit energy-use savings over low-mass construction in local climates with truly huge diurnal daily temperature swings. "

This ORNL report is regularly used by some to say that mass is overstated by ICF. You need to read the report very carefully. What the report actually says is:

... according to ORNL data it only hits double-digit energy-use savings over low-mass construction ((( WHERE THE LOW MASS CONSTRUCTION IS IS BUILT TO THE SAME R-VALUE AS THE MASS CONSTRUCTION))). That's kind of important since most homes are not. Therefore, add the extras -- e.g. bring 2x6" stick up to par with staggered stud or external foam and then look at the report.

Regards.

Jeez, TexasICF, give it a rest. The means by which ORNL established that the concrete in an ICF house adds relatively little in energy savings was to build houses that were otherwise identical, including R value, and then heat and cool them. That's how testing is done: eliminate all the factors except the one you are investigating. That tract-level studwall houses aren't insulated that well means nothing because you can add EPS to stud walls without pouring concretel. I think we can assume that folks who visit a green building site will not settle for code minimum.

As for the overstatement, my ICF contractor swore up and down that Arxx blocks were an effective R45.

Posted By jonr on 17 Aug 2011 08:54 PM
I'd like to see any pricing comparison for:

1) ICF basement with wallboard
2) Poured basement + exterior foam
3) Poured basement + wallboard and interior insulation
3) FPSF monolithic slab with a fully exposed, wallboard+wood+foam+siding "basement/garage"

Say all at the same R value or thermal performance.

Jonr-
Over the last year I actually got quotes in almost all of these areas, so I can share them with you.  Most of it will be DIY b/c of my construction background, however I will have experienced help from the industry on site.  I did do both prices...materials priced for DIY as well as fully installed prices.  I can show both.

1- DIY Hobbs (r-25-30ish) ICF basement, 9' 4" walls, 1/2" gyp on exterior walls:  $7,500 for forms, $2300 concrete, $900 pump, $1000 rebar/other, $850 waterproofing, $1800 drywall and materials. = $14,350

1A- Pro installed everything- horizontal blocks (Logix)- $26,000 blocks and concrete, including pump, $1100 waterproofing, $3500 drywall installed- $30,600

2- Poured basement with 2" exterior XPS foam placed in forms prior to pour (all pro installed)- $24,000, $1100 waterproofing, 2x4 + r-11 interior batt walls (materials only, all DIY)- $1650, $1800 drywall (or $3500 drywall pro installed)= $28,550

3- Pro poured 8" walls- $21,500, $1100 waterproofing, 2" interior XPS foam- $1300, 2x4 framing w/ r-11 batts- $1650, $1800 drywall= $27,350

4- This I never considered since we always want a basement.  Plus our site slopes, so a walkout basement makes sense.  However I quickly came up with these prices based on numbers I have from concrete slabs and framing for the first floor- entire 4" slab w/ 2" XPS below slab, 2" XPS down 24" on sides and out 24" around perimeter-  $1800 for foam, roughly 28 yards of concrete @$110= $3080.  Install for the basement slab was $5500, so I assume this would be around $7000+, 2x6 OVE framing with 2" XPS foam over 1/2" sheathing, cement board siding, all DIY install (materials only)- $2800 framing materials, $1400 foam, $1100 strapping/screws, $1400 cement board siding= approx. $18,580+.   While this option is slightly cheaper, it still is not worth it if this is not something someone wants.

Posted By toddm on 18 Aug 2011 07:59 AM
Jeez, TexasICF, give it a rest. The means by which ORNL established that the concrete in an ICF house adds relatively little in energy savings was to build houses that were otherwise identical, including R value, and then heat and cool them. That's how testing is done: eliminate all the factors except the one you are investigating. That tract-level studwall houses aren't insulated that well means nothing because you can add EPS to stud walls without pouring concretel. I think we can assume that folks who visit a green building site will not settle for code minimum.

As for the overstatement, my ICF contractor swore up and down that Arxx blocks were an effective R45.

  On Mars, mayhaps?

I have nothing against ICF, I have everything against BS straw man arguments to promote it. (And don't get me started about the BS arguments used by the spray foam guys...)

There are MANY documents available online from ORNL documenting the actual thermal performance of ICF vs. low mass-equivalent U-value structures.  Yes, there's a modest dynamic performance boost from the  thermal mass of the concrete, but not enough to offset a 5% cost increase over other methods.  Adding R value to the other methods can usually more cost-effectively null out any performance gains.

The cost of concrete varies widely with region & location- where it's cheap ICF can look pretty good, but where it's expensive the cost-adder may not always be worth it, despite the very substantial structural strength improvements.  In hurricane zones the structural aspects of concrete alone may make ICF "worth it", but I don't expect it to become the method of choice for tract housing anytime soon.

Posted By toddm on 18 Aug 2011 07:59 AM
Jeez, TexasICF, give it a rest. The means by which ORNL established that the concrete in an ICF house adds relatively little in energy savings was to build houses that were otherwise identical, including R value, and then heat and cool them. That's how testing is done: eliminate all the factors except the one you are investigating. That tract-level studwall houses aren't insulated that well means nothing because you can add EPS to stud walls without pouring concretel. I think we can assume that folks who visit a green building site will not settle for code minimum.

As for the overstatement, my ICF contractor swore up and down that Arxx blocks were an effective R45.

Ready fire aim?   ORNL did not establish that.   ORNL does not build houses.  ORNL does not heat or cool them.  This particular ORNL test was a compilation of several tests some of them dating back a few years and most of the compilation was theoretical (unlike the largely empirical study just completed by MIT).   You can find all this in the intro/abstract.

Regarding BS claims, I don't believe I've made any.   I am, however, not a fan of the more temporary construction methods like stick - however, you might piece them together to get close to ICF.   Regards.

Turns out the ICFA, the industry's trade group, built identical houses in Knoxville in 2000 in a joint test with ornl. Couldn't find the results at forms.org. Instead, it cites energy savings from a BS study that compares energy consumption in ICF houses to stickbuilt counterparts next door. No one here will argue that a well insulated, airtight home will save energy and money. The BS part of this approach, and yours, TexasICF, and the MIT study, is the unstated premise that you can't get the insulation and air sealing without the concrete, Anyway, TexasICF, there are at least two houses built by ornl and your trade group, (Actually, many more besides.) What are the results?

lzerarc, thanks very much for the pricing. Do options 1,2,3 include the floor slab?

actually no, I did forget to add that to the cost. So you would need to add that to the totals. You would also have some more excavation costs int here as well vs the SFPF. However you would need a 2 story exposed house, and some builders charge more for that in our area due to additional equipment they use (lifts, larger cranes, more scaffolding etc).
Another issue that might play into is slightly larger heating requirements since basements tend to be better regulated by the earth. Most people in our 7400 HDD do not even heat their basements or cool them. If so, its done with very minimal air. Most ducts in the basement ceilings leak enough to keep the room comfortable

ICFhybrid - That sounds great, oooh 10 x 18, I'm jealous. I have to rethink my house plan, to save some money so I'll probably have a much smaller space but hopefully still big enough. I'll have to look up insuldeck ceiling. What are you going to use to finish the inside walls? I'm so glad to have found someone who is doing this. Thank you for all the information!

What are you going to use to finish the inside walls?

That's a good question. I'm glad you brought it up. I need to be thinking about that. :-)

Suggestions?

Cedar?

Plastermax, so it looks like white-washed dirt?

Plastermax sounds interesting. Are you using that in the rest of your basement? If so, would you DIY? Hard to find good information about that. I can't seem to find it anywhere near me, Ontario. That would be cool if we could do it ourselves (notice how that y changed to an o when I was talking about myself
Do you think you could just use exterior grade plywood or bluewood?
I guess you'll have to decide before me, so let me know what you choose, please.

Hi Texas ICF.
I was a carpenter during my construction life and wood is what I did until late in that career when I discovered the benefits of ICFs and began building ICF-only houses; I used a fair number of different forms. So, though I still love wood (for interior uses) now I'd only build ICF.
I'm not good with a computer so if this is a duplicate response please forgive me.
I believe you are right on regarding mass effect.
Here in Colorado my SIP house (with spray-urethene roof insulation, triple pane low E windows, careful assembly with good sealants at all joints) drops 6˚ to 9˚F overnight on cold winter nights (0˚F range). My ICF house (same roof insulation, better u-value windows) dropped only 3˚F during SIX days two winters ago when the boiler went out during a prolonged period of 0˚F to 10˚F temperatures.
When my energy rater read the thermal sensors cast in the walls of that house he discovered center of wall temperatures ranged from 45˚F to 48˚F, depending on compass orientation. My thinking on why this should be is that the insulated concrete is "wicking" thermal energy from the footer & soil up into the wall. I mentioned this to a friend who told me he thinks ARXX did a study on this some years ago; said study came to the same conclusion.
Almost zero air leakage, good CONTINUOUS EPS insulation, and mass walls combine to make a superior structure. A structure which is quiet, won't rot or burn down or blow away. Where's the problem?
Below I attempted to attach an article concerning a recent study at MIT which addresses the sustainability of concrete structures, and a report from CTL which is, I believe, the origin of the R-45 or R-50 claims made by ICF salespeople who have not themselves read the report.
Cheers.

/Users/felixmarti/Dropbox/Documents/PT reborn/Energy items/MIT weighs the lifecycle impacts of concrete.webarchive /Users/felixmarti/Dropbox/Documents/PT reborn/Technical, NUDURA/ACI + Code & test docs./CTL equiv to R5… Compressed.pdf

No, not treated wood for this one. It's a food storage room and I don't want the chemicals in there. It should be dry enough that cedar or even Douglas Fir would be okay for shelves and whatnot. Plastermax would be a nod to the white-washed dirt cellars of yesteryear. I could gouge the ICF foam out of vertical channels and inset wood to look like support posts and use rough plastermax inbetween. I hadn't really planned on using Plastermax anywhere else. Except maybe the wine cellar. I might want to go for a hewn stone look in there.

In either case, for just one or two small rooms I might DIY it, but for anything bigger I'd rather contract it out unless I couldn't find a contractor I had confidence in.

I'm going to wait on finishing out the rooms until I see how they perform, temperature and humidity wise. So far, they seem to be coming out as planned, but everything is still opened up. I'll probably wait until we've been through all four seasons. Since I'm thinking of a "dry" root cellar, instead of a more humid one, we will also have to wait and see how that works out for the vegetable storage.

Here is a link to an article on how a modern root cellar might be constructed....

http://www.organicgardening.com/learn-and-grow/building-root-cellar

ColoICF, Do you think that by using Polystyrene insulated forms for the footer, that the center of wall temperatures would be better?

Sheesh. It's like the movie Ground Hog Day. Yes, ColoICF, a concrete home will cool slower than a low-mass home in same manner that a five gallon bucket of boiling water will stay hot longer than a one gallon bucket. (Analogy not perfect because the bigger bucket has more surface area radiating heat.)
but put them back on the stove and guess what? It takes the same number of btus to reheat each to boiling (again, assuming equivalent surface area.) You haven't saved nearly the energy that you think you have. Here is a link to an ornl report on the joint icfa/ornl test houses in loudon tn completed in 2001. http://www.eere.energy.gov/buildings/building_america/pdfs/db/30962.pdf

The cliff notes: the thermal mass effect of ICF in tennessee is in the 8-10 percent range. The ICF house is 5-10 percent tighter. The jury is still out on ColoICF's earth coupling theory. I assume it is still out judging by how deeply the ICFA has buried this study, relying instead on BS research.

But that doesn' mean that we can't learn something from the ICFA. Hey, my analysis shows that I am 40-50 percent handsomer than the gents at the Golden Acres Nursing Home. I am still waiting for the babes for each arm.