What are the REAL downsides of ICFs?

Thanks Martin, exactly what i was looking for.

Let's assume a design for a passivehaus standard or a near zero energy house...

would you believe it is achievable with ICF ??
i don't see problem to adding more exterior insulation
( seems same as with other exterior insulated method .. )

What is the usual cost for super air sealing requried for those standard with more general construction ?? for Persist the cost of the membrane + man time to apply and detail it ?

on the ICF there is not much more than openings to seal thus a small save in labour here??

I also like possibility to hold up larger weight on walls of icf

( per example my first floor has a few 40ft long steel joist with concrete slab on it )

Lastly, would you personally rate ( i ask you Martin because i like your answers!! straight and true )

higher an ICF constructed residential than other stick framed methods in terms of value
if everything else is same ??

Have you looked into QuadLock offering ??

http://www.quadlock.com/images/icf_components/R-Values/ICF_Walls_R-Value...

their R59 really gives ~R50 @ 3.75R/inch

it is very easy to achieve R40 walls without finish

i know for fact ( discussions when purchasing back then ) that they'll sell the insulation panels
( the one u stick in between ) at regular EPS 4X8 equivalent price when purchasing full system

i'm very much leaning toward this for my 60'X100'X20'H shop/factory next year

The problem with fastening finishe on the exterior is not valid since using the connection clips provide for a very stiff connection ( holds #8 wood screws seriously tight )

Some would point to the embodied energy of the concrete in the ICFs as a downside. I know the ICF industry would counter with the reduced energy savings as an offset to that, for what it's worth.

As Martin mentioned, it is very inconvenient to modify or demolish. It can be done, but not in a conventional way.

The only other downside I can think of at the moment is that some ICFs are pre-assembled. The positive is that their built in a factory setting, and the QC is usually higher than site built. However, the downside is that you (pay to) ship a lot of air when sending the forms to the jobsite.

EDIT - Thought of another one. Depending on your opinion of foam insulation, it could be a downside to some.

On the topic of R-value, the ICF industry will use air infiltration data to argue that their product produces an effective R-value much higher than their static R-value. I feel that's a discussion left for a different thread, though.

Yes i've also seem alot of false R value claims.

I guess we all know better than to trust any other than static R value for basic insulation setup.
Unfortunately not everybody does ( just look at the radiant barriers etc.. )

I agree that modifications is not easily done with ICF
but i don't believe it is a "real" downside ..as if buidling is correctly planned in advance,
you can have an exterior "recyclable" shell and modify as one wish interior divisions
and exterior sidings ( modifying window openings is another thing though, but still possible )

demolish is out of the question, as i review ICF as a long lasting building method.

True about EPS, alot of people seem to have different opinion and i cannot argue that most plastics are/will be a nuisance if we do not find a way to dispose of them.
However, EPS seems pretty stable if hidding from damages, thus should serve its 2%plastic weight
for quite some time in the future.

A few small thoughts. I have only done one, 6' wall around a house w/ ICF's, and they were good for below grade. However, they were a LOT of work (bracing) and require a LOT of exact planning( penetrations, door/window framing, etc). People do it all the time, so it must not be extraordinary, but accurately building a two-story with them will be an undertaking, in my limited experience. We had two wall blow-outs, too, so plan for that to happen. Also, plan for the extra weight on the footings.

No offense, John, but blow-outs are mostly seen on jobs with inexperienced ICF installers. But you are right to provide the warning, for those having never used it.

And yes, if doing the whole house, the footers have to be a little bigger and/or deeper. I don't know if that's a downside or not, but certainly something to consider.

I guess I can chime in since I have been down this road and every other road I could find, and it led me to ICF as my final choice. I am currently in the middle of my first DIY ICF build, full basement and main level. Before I arrived here, I looked at about everything as many know. Being in zone 6, needed something efficient. Looked at Sips, thick foam, advanced framing, and the top contendor was the prefered double stud wall. My findings and cost comparisions are a little skewed since very few of my numbers include labor since I was doing it.
However my reasons for choosing it over double stud was:
strength (tornado alley)
air tight (easier to achieve)
continuous insulation/strength from footer to top plate without mud sill area
decrease sound (STC may be comparable double stud however)

I am using vertical forms with a tappered post and beam engineered design resulting in a higher average r value of about 30. It also uses less concrete so my "embodied" energy reduces as well. With energy modeling, we found in my zone that the head load bump from r30 to r40 walls was minimal (about 1200 btu). WIth triple pane windows, properly designed solar temporing and home layout, my heat load for the 3600 sqft is still around 24k.
Super insulation and energy conservation certainly takes lead on this site, however I also believe that part of being responsible is also building structures that last. Obviously a concrete home will outlast a wood house. The details on wood need to be correct. Moisture issues and risks are higher. Mold risks are much higher.

We are currently setting trusses now. Feel free to check out my ICF building blog:

http://www.lizerhomestead.blogspot.com/

John Klingel: Which "brand" of ICF u used ?? because this influences the friendiness to "n00bs" to a high degree.

Planning is nothing but easy with ICF
took me roughly 6months of evenings and off times to plan the house construction once i was set on ICF and few other key products. I didn't make a single error on dimensions or locations of parts.
And let me tell you that my house is large and complexe ( was my first building also .. i am still a n00b ! )

Bracing is not that hard if you know where and when , need to study the product and have some basic mechanical engi. knowledge.

I did a 40ft high ( 40ft of ICF from top of footing to last block ) house of 80' X 45' size as my first time,
and i didn't find it that challenging, was pretty straightforward i'd have to say )

I planned all openings and dimensions based on 1FT heigh increments and 2" horizontal increments, and builded accordingly.
So i really never had to cut some blocks horizontally ( except for a few door openings inside the buidling ) and all windows were custom sized to fit the openings.

Not a single blowout might i add, and i dind't use that much bracing at all...
( might be because QL is placing the clips where they should be, between panels ... )

Jesse Lizer: nice work !! might i suggest you install a minimum of 2" addition EPS on the exterior??
what is used as fastening strips on this brand of form ?? the vertical strips ??

I used only regular 2.25"/concrete/2.25" forms, had i knew better back then,
i would've add a minimum of 4" of EPS on the exterior side.
Still the house is very comfortable ( even though we have some current window and leak problems)

I agree 100% that building green = building that LAST
because building twice something that has "half" footprint and 80% original price,
usually costs 2-3 times more and pollutes as much.

I am "still " seriously considering ICF for all of my next projects which will all be much more energy efficient.

Some ICF manufacturers may or may not calculate the R-value correctly. I know of one manufacturer/system that erroneously calculate the R-value based on the average thickness of foam, not the 'lumpy' method, see http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/25547/F.... Although the quad lock referred too above does appear to have continuous insulation of same thickness, so this issue would not apply to that specific product.

adding the 2" drives the price to energy savings/payback beyond reachable. The r30 average wall in foam accomplishes a fairly strong r value for my climate. Climbing much higher, and certainly above r40 makes little financial sense.
The black strips are 2.5" wide and are continuous for attachment. They are strong and provide great attachment for about anything. They also held the vertical rebar in internal clips during assembly.
It took me and another person about 2 days to put up the entire level of the foam wall. 1 more day to build window boxes and set them.
The forms are Hobbs Vertical ICF, and the contour panels which are precut to the height of your wall (very little job waste and fast assembly) are 16" oc vertical spacing. They are 9.5" wide out to out with a 2" web of concrete. At each black stud, they flare out to be 2" foam with a 5" concrete column around the vertical #4 bar.

Jesse: looks like a nice engineered product.
I do not hate the vertical layout, puts the strips where they are supposed to be.
R30 is not that bad either.

Would you be able to pull out a quick price of component per SQ FT this system costed you ?
( just the components.. ) just for sake of comparison.

Straight walls looks easy with this system
i guess you used bottom and top tracks to keep everything straight ??

I thing i do not agree with the manufacturer is about having more foam and less concrete.
My house weight a little more than 1 million pounds, and having more concrete in the walls was a requirement for everything to hold up ( most walls are 8" concrete and some are 12" concrete )
That does not change the quantity of EPS, which is also something u can continue to add on
as much as you wish on the exterior.
Regular foam boards usually cost a lot less than the same size of boards from ICF forms.

anyhow, nice product and wish you success in your project! :)

Jin
an often misconception with concrete walls/ICF is that you NEED a solid concrete wall when in a lot of cases 6-8" easily does a foundation and 4-6" can do the main level depending on wind loading and other things. While I am not an engineer, I do work with them on a daily basis so I am quite familiar with it. A lot of engineering has gone into this particular system, and they have the results to back it up. If you read the flexural testing, compression testing and other tests, you can see that the post and bond beam design performs extremely well, structurally. Steel and concrete is a powerful combination, and when designed together it performs well to maximize the charactoristics of each. 6" and 8" walls are usually easily engineered with perscriptive paths. However this system is engineered specicially for each and every project, including steel lintel design, rebar size and layout, etc. You then recieve a sealed and signed set of engineered drawings with the foam package.

As mentioned, all pieces came precut to the heights needed, no matter what they are so this eliminated a lot of construction waste. I think at the end of the project I have about 6 trash bags full of foam pieces, cut furring, etc. The corners are extremely strong and feature steel on each side with 2" foam within. Due to the vertical nature, they are easily straightened with strong backs at the top of the forms screwed to the furring strips. Bracing and kickers is only needed every 10+ feet. The bottom is secured with a supplied metal track screwed to the deck or shot to the footer with a ramset.

My project ended up around about $4.35 sqft for the foam, plastic, corners, and tracks, delivered to my site. My added costs were screws, a lot wood bracing (that I am using up in interior wall plate framing and truss bracing), rebar, and concrete. I have about $1k worth of bar and supplied in it, and then the nearly 4000 sqft of wall surface used only 52 yards of concrete. By comparison, a full 8" wall would have used closer to 100 yards of concrete.

So you get the best of both really. A wall much stronger and better for long term durability than wood and a decent r value in a 10" wide wall.

Jin:

I can also confirm Jesse's 1st sentence above. An 8" foundation wall should not only suffice structurally, but should not present any problems to a local building code department.

Jesse: price doesn't seem too bad it is includes engineering services and rebars!!!

As for the thickness of the walls, when using ICF for basement or first floor only,
nothing is wrong with using 6" walls with rebars, but once u start going up
and use long span floors with concrete/steel decks u get to another level.

I have a "situation" on my rooftop that was designed to hold up a very large sap ( jaccouzi u call them ? ) or a small pool , and i've used 12" of concrete with a super footing and almost double rebars for that " vertical H form " ... but it could probably hold near 200 000LBS on top of it, and is way overkill ( it's 40ft high also )

I understand the point of it being a residence, and as with insulation, too much usually doens't yield anything other than additional expenses, so your system with it's savings and engineered forms looks very good!! :)

On a side note, i've seen and heard of many many builders trying to save on rebars,
and i have a few local stories or failed garage door and large window lintels.
Rebars and proper lintel design is a must with any structural concrete,
thus the engineering service provided to you with your package has a real value here.

On my house, i had to figure out the lintel design myself
( again way over did to be sure ) but it was fun and a good learning experience.

Mike: Yes, blowouts are obviously a result of human error. I was just pointing out that one should be ready, because having concrete streaming out of a wall at huge $$/minute is not real cool. We were lucky that we had stuff and people around to patch the blowouts, or the whole job could have been quite compromised. Jin: "I did a 40ft high ( 40ft of ICF from top of footing to last block ) house of 80' X 45' size as my first time, and i didn't find it that challenging, was pretty straightforward i'd have to say )". Wow. That is all I can say.

JOHN: your word describes my feeling when i got to the 2nd story of the building and finally realised i had WAY over done the dimensions that seemed perfect in my 3d software !! :p

yes, 45x80x40 high is kind of large for a house. have fun in the tub on top.

Unfortunately, the roof terrace has been delayed ( just as much as the basement gym and HT room )
to unforeseen events ( defect products installed etc.. )

But i am sure i will get to it! one day :)

Here is a quick pic of the 5th row of blocs and a more recent picture of the still unfinished exterior
( had 2 shoulder surgery this year, trying to mange 2 business same time, 2 kids within the house construction time ... some tough years but still alive and kids are healthy so! :)