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ICF Any experiences? good, bad, etc.

Dave_Richeson's picture

I am starting a 2400 sq. ft walk out basement this spring. the plans are for Insulated Concrete Forms. I've got supplier information on 4 or 5 different flavors. Does anyone have any good, bad, stories or warnings, advice, etc. to offer. I checked the archives, and there is not much. Any help is appreciated. TIA

(post #164758, reply #1 of 43)

Brace it well.....brace it well....brace it well.

you may need to pump the concrete.

You are buying an expensive system for the insulation value and because you do not own forms.

near the stream,


(post #164758, reply #2 of 43)

I did an icf foundation about 6 years ago. I had done several regular pours, renting the forms and all, thinking these new light weight forms would be simple and cost effective.
What a mistake!
The only part off the walls that remained straight were the parts where I ran out of rental bracing and finished with 2x4s. If you need to pump the concrete- A pump truck (idleing) goes way too fast for these forms to handle.

When I was done the building inspector made me cover all the styrofoam with sheetrock-even in crawl spaces. fire code
The finish on the exterior was less than acceptable, and difficult to apply .

I wouldn't do one again!

(post #164758, reply #3 of 43)

Dave .AJ is correct brace it well. Buy forms that are open enough to use regular concrete . I used a convayer truck on my job. I would use the system again. I tied my corners together with 1/8 " cable to keep the tops of the forms from pushing out as we poured . don

(post #164758, reply #4 of 43)

Dave - Just finished doing a foundation with rastra and was impressed with the speed and lack of bracing required. The panels are heavy and that seems to help with stability. While brittle, they are easily repaired with canned foam during setup.
If energy-concious, I'd consider the 14" thick panels which have an R40 rating.
Concrete was 6 sack grout (pumped) with low slump (about 9) and went smoothly.
Less time forming, no stripping, and no foundation insulation are plusses; higher cost (10%) is a negative, but this is an apples vs oranges deal when comparing with conventional foundations.
I'd do it again; in fact, I'm redrawing a house for next year from frame to rastra.
Best and have fun!

(post #164758, reply #5 of 43)

I am considering doing some building with Rastra - you may want to check them out if you haven't already. My understanding is that the Rastra product has somewhat less insulating quality than the other products but the trade off is that there is less potential for damage and you don't provide a nice, cozy place for the insects. I also understand that is cutting it is fairly dusty, unlike the polystyrene based products.

Perhaps Don could address some of the tricks and problems in working with product.

There should be a number of posts in the archives dealing with ICFs. You should find a variety of suggestions and ideas if you can figure out the best search terms to use.

(post #164758, reply #6 of 43)

Pump slow & with not much slump. Someone I know does this & they look great. I found his homes to be less straight than regular framing. But you have to look real close to see the difference.

(post #164758, reply #7 of 43)

Just did a first floor w/ PolySteel ICF. Disaster because I didn't do it all myself. Putting up the forms takes a lot of patience and not much skill - sort of like Legos. Putting in the steel was a piece of cake. Bracing was easy, but used a ton (literally) of 2X4's. I had a lot of advice from the guys I bought from. Walls came out very, very level, but not as straight. Invest in some straight 2X4's to keep walls straight. Doesn't take as much bracing as you might think. Walls were very strong as erected, and withstood pouring very well. Used 2X10's for bucks in doors and windows. if I had it to do over, I'd use their PVC Bucks. 2X10's tend to warp and distort. I solved that problem, partially, by determining wich direction they would cup, then running three kerfs about half depth the length of the bucks on the convex side at about the third points across the bucks. Then put the convex side out so that when the concrete was in the walls, the bolts would hold them flat. If you put all the steel they call for in the walls, you have problems getting the concrete to fall past it and fill the voids. You MUST pump the concrete, and they require a special, small aggregate mix that will pass through a 2" pipe pon the end of the elephant trunk, w/ an elbow on the end to keep it from flowing too fast. Slump is EXTREMELY critical. I can't recall, but I think it called for a 3-4 inch slump. The concrete also has to be 3500 PSI mix. I hired it poured, and got a BAD batch of concrete, too long in the truck, temp too hot - over 90 degrees - and starting to set. I have a mound of waste concrete in my yard that looks like an African veldt termite hill - about 1/2 yard, wasted by the pump operator who was not experienced. According to the block supplier, you did not vibrate it, but rapped hard on the forms to settle tha concrete into a homogeneous mass. Worked well till the concrete went bad. Vibrating the tall column of concrete supposedly settles all the aggregate into the bottom. You pour in strata of about 2 blocks at a time, going around and around the house. When I do it again, I'll find a way to vibrate better than rapping. I wound up w/ some bad voids that were not discovered till after it had cured and I was building the second floor on it. Had to open up the walls, clean out the rubble and fill w/ 8,000 PSI non shrinking grout. The walls were amazingly strong, even w/ the voids. Had one as big as my torso that took over 8 - 50 lb bags of grout to fill. When the mix was good, it filled in very, very well. Bottom two courses are very homogeneous - then the bad mix came. If you want some great propaganda, get the Hometime tape w/ Dean and Robin on the subject. they poured in MN in snow - great weather for this, since the mix stays workable much longer. Forms give insulation to well below freezing - down to about 18 degrees Fahrenheit. I would posit that a vibrator that does not enter the poured mass at the bottom would drop all the concrete to the bottom where the pool is, and keep it from massing on the horizontal steel and blocking the space.

Would I do it again? You betcha, Little Beaver! I love what I have now, and plan on expanding the house in about two yrs. The temp has been very low, and even w/o windows, the inside is measurably warmer than outside. If you have any specific questions about my experience, I'll be glad to give you all the detail I can remember. God luck

(post #164758, reply #8 of 43)

I used Eco-Block for my basement, and it came out straight, level and square. The building inspector did not make me cover the interior, although I've been doing so gradually for convenience and looks. I poured my own, and I've seen a few others poured since. There's a big difference between pouring a flat-wall system like Eco Block or Blue Max and in pouring a waffle wall such as ThermaWall. I think that a waffle wall requires a pump. I didn't pump, and think that in my case, pumping was no more necessary than it is on a traditionally-formed foundation. Small aggregate is key, and because the concrete stays hydrated for the time of its cure, you may end up with a stonger wall. The Portland Cement Association has numbers to back this up.

Cost is an issue. If I'd paid someone else to form and pour with ICFs, I don't know that it would have made sense. As it was, and valuing my labor as I do at $0 per hour, my foundation cost about what a traditionally-formed and uninsulated foundation would have cost. I got insulation and the fun and satisfaction of doing it myself as payment for my time. Considering the troubles I had with ensuing subs, I should have taken the ICFs all the way to the roof. I doubt that it would have cost more, and I'm sure that I would have finished sooner.

Finishing the exterior wasn't that big a deal. I screwed on expanded metal lath and parged it with 2 coats of cement-based stucco. You can also go right over it with an EIFS-type of finish.

I'd be a bit concerned about termites in the south, but at least one company, whose name escapes me, makes borate-treated forms.


(post #164758, reply #9 of 43)

Hi: Below is something I typed 6 months ago and never posted. Thought it was just too negitive. I putting it out there now - under a bogus name because I don't want it traced back to me. But it's all true - as I saw it:

Here's the ugly. The some of you guys are gonna hate this!

There's a ICF house going up a few lots down from where I just finished building a house.

I suspected something was wrong from the get-go. The heavily wooded lot was cleared by a tree cutting contractor, with chainsaws and a stump grinder, no heavy equipment. Later, I really knew something was awry when the builder asked me if the footers should be inspected before or after pouring the concrete. He is a nice old guy. Said that the homeowner expects completion in 5 months. A few weeks later, some guy is out there trying dig up the stumps of up to 24" diameter trees with a back hoe! OK, I'm already off topic, so I'll cut to the chase.

8 months into the project an ICF foundation has been erected, garage and half basement concrete floors poured, and floor system partially complete. No roof yet. A few guys have been there almost daily, but progress is slow. Not a single straight wall in the place. Everything out of level (that started with the footers). One wall has a 5" bow in it (the owner told me this). One inch bumps in the TGI floor system. Notched LVL girders. 9' high wall poured all at once (concrete dropped 9'). I could go on and on!

My point is, that while I know that there are great builders out there building great ICF houses, it isn't happening in this case. A little background. I talked to the owner; he had a hard time finding an ICF builder. Ended up bringing in this guy from the next city about 35 miles away. I talked to the concrete pump truck driver, he said that he had been driving the pump truck for about 2 years and this was the 3rd or 4th ICF house he'd done. I watched them pour for a while, and they had 2 blowouts during the 45 min I was there. Apparently ICFs aren't very common around here, probably because of our mild mid-south eastern US climate. It's the first one I've seen.

All of the above was simply fact and observation. Now we get into opinion and speculation: So, in the end this guy (the owner) is going to have a vinyl sided house with stucco(?) foundation that cost more than the other brick homes in the neighborhood, with, say $50 to $80 a month less in heating/cooling bills. Did he do his research? - yes. Did he use building techniques that were commonly accepted in this area - No. Is he making a wise investment? - Well, probably, if he is going to live in this house for at least 20 ? 30 years. Resale value? - I doubt it; people around here just don't know what ICF is. Is his building project hanging on the edge of possible failure? No, just as long as the current builder doesn't decide to walk. I think his "main man" already did walk as I haven't seen his truck in about a month.

All I'm saying is if you want to use other than standard building practices, use the utmost care in selecting your builder, and don't forget to take into account that if you select the cutting edge building techniques, you are increasing your chance of ending up on the
i bleeding edge.
Oh yea - and it's gonna take you longer.

b Current Update:

16 months after the project start and the people have moved in. House still isn't completed. I think they ran out of money. Some of the exterior is not completed, there is no interior doors (special (back)order) and there is a lot of other trim missing.

PS: The guy in a previous post who said he
i should have
done it himself is out of his tree! This is not a DIY project! BTW, I'm not talking about Andy.

(post #164758, reply #10 of 43)

Check out the ICFweb. You can learn a lot. I have been studying ICF for several years and have been on two pours and seen a half dozen structures. My first comment is: HELLO, it's concrete. It must be done right regardless of how it is formed.

I would start with ICF dealers in your area. The reputable ones have a vested interest in seeing projects completed successfully. They will either point you to an experienced ICF builder or figure out how to find someone who wants to be. In that case, they will be on site to teach/supervise them how to do it right. ICFs are not rocket science, but they are concrete forms and you don’t get a second chance to do it right. Previous concrete experience is very important, but there is nothing like this type of form in industry.

There is no question in my mind, after an admittedly big investment of time, that it is the only way to build a residence or small commercial building. I am talking ICF all the way to the rafters. After all this, I could not stand to live in a new stick-built and SIPs would be a VERY distant second.

There are a number of ICF blocks that have come on the market recently that have learned from earlier mistakes. Do your homework and pay the little bit extra, it is very well worth it. It is not just a question of saved energy. There is a hard-to-pinpoint tranquility in a high-mass and well insulated structure. Good luck.

(post #164758, reply #11 of 43)

We have been using ICF's for nearly twelve years. We evolved from Log, Timber frame To SIP and ICF. The main impetus for us to use ICF's way back when was because we had a tough time getting a concrete sub to deliver a plumb, square and level foundation or basement.(mind you, I am not knocking the guys that make their living in this capacity. We rarely had a square box foundation on a level site) About the only time we were able to get this was when we requested to work with the sub....ultimately the cost issue became debatable since we slowed productivity and increased materials etc. in our quest to obtain the best possible product. I lived in Europe and the Middle East during my school years and had seen ICF's there. Someone showed me a flyer of a company that produced ICF's in the U.S. and wondered if we may be able to use them. We bought our first order of blocks and received them with no installation information, no code approval, no nothing, simply a tractor trailer load of "foam blocks". Our first project was a basement (will never forget it) the walls were to be 10'-5" tall. The blocks were 9-3/4" tall, making it tough to hit grade because we were removing the web of the block as we made the horizontal cut. The longest wall was 76' long with three small windows and a 6 foot door. The walls were perfectly straight with minimal bracing, before we poured. We thought we had it made, we built the basement (3 of us) in two days...a savings over our usual subs by at least 3 days. It went down hill from there, we learned the hard way, BUT it turned out well. We had no knowledge about the pour rate, we had talked to the guy that sold us the blocks (He was in Massachusetts, we were in Oregon) We used our limited amount of "concrete common sense", blew out a 6' tall section of the wall, had voids in one area, had bowed walls in other areas. We fixed everything to include shimming the walls out to make the finishes straight, cost a bundle of time and money. Today, the technology is ten times better, the old ones are still on the market, although some come and go. The newer blocks are far superior to the old ones in most cases, there are many different styles. We have used 35 brands to date, some we will never touch again, some we favor for particular applications. We have been involved as a subcontractor or a technical assistant to another sub, builder or homeowner in nearly 1000 ICF projects. On some projects, you can lead the horse to water but you can't make it drink, others, what you say is gospel and they respect it, some people know it all before you get there, others listen, some people shouldn't be on the job, others are eager to do it right and won't do a thing until you sign off on it. The success of ICF is in our opinion no different than the success of any other building material, the installion team must have more than one trade experience though, ICF's require Concrete, Framing and general layout and finish knowledge. One of our lead guys used to have a title under his name "The dryer vent man" ....With ICF, EVERYTHING must be considered at the time the walls are formed. We drill most small penetrations, but life is not fun when you forget the dryer vent or downdraft at the second floor elevation. We are asked to build houses all over the country, mainly due to reputation. As for speed and accuracy, last summer we put up a 5900 SF three story rectangular house with 12/12 pitch, to the gables, two sizes of concrete, 14" basement that stepped with the grade for a stone ledge, and 6" concrete above, 36' overall height, two pours, including all framing inside, stairs, loft, used wet 2x12x26 rafters on 16" centers, waterproofing on the basement, cornice, ready for stone, roof and exterior doors and windows, passed framing inspection (paid to have county check framing prior to mechanicals so we were sure to meet local code).....start to finish, 15 days, worked 12 of those days. Just like anything else, ICF is fast if that is what you do. Just like anything else, the ugliest trim job is the one the framer did because he needed the work and the builder's regular guy was too busy. ICF construction is still a novelty in most areas, but if you ask a homeowner of an ICF home if they would trade the benefits of it for a wood frame house, 99% would tell you "NO WAY". Here in Texas, the typical added cost is paid back in less than five years with most owners saying three. We have seen our share of ICF disasters, we are called on a regular basis to "fix" someone else's mistakes, unforunately, most of them only deserve to be torn down. I would agree that there are a lot of problems with the methods that many ICF manufacturers use to sell their product....It's easy, just like lego blocks, but there are just as many if not more guilty people that THINK they can do it themselves....This is obviously true in the auto repair business...ever notice how many cars don't leave the driveway anymore? If you plan to use ICF, Do your homework, go to other jobsites, watch and work, do more than you think you need to do before you start a project or hire someone to do it, the more you know before you get involved the better, once you start and have a second though, it is too late. More information about ICF's is available at,, or by using a search engine and inputting "insulating concrete forms"

(post #164758, reply #12 of 43)

Thanks to all. These are just the type of heads up stuff I,m looking for. Like Andy I am going to form and maybe pour this myself. I say maybe pour, because labor might become an issue.

This is our "dream home" and I intend to everything I can myself. That may also depend on how many guys show up when I run up the "help me" flag. After 24+ years in construction and maintenance I've built up quite a labor pool of guys that owe me for free work. The free work was my choice with the payback clearly stated up front. We'll see.

At any rate this house is designed to be a passive solar assisted dwelling. The insulating value of ICFs is both mine and the engineers specification.

I have a ton of experience in both flatwork and forming walls. Every thing from basements to bank vaults, with retaining walls,ditches, and a few bridge head walls thrown in for good measure. To quote "blue" I've at least had a chance to "booger" them all. That is what I want to avoid with this one. After all, I have to live with the co-owner.

By the way this place is going to be on Passive Solar tour site on the web, as well as being open for inspection by interested builders a few times durring the project. I don't expect it to be a speedy job. I have a day job, so the whole project wiil stretch out over maybe two years. I'll post the web address after we get started and try to post some pictures here as well.

All sugestions and warning are appreciated.


(post #164758, reply #13 of 43)

Ian....What's the best company for a foundation?....northern low cost and easy.

near the stream needing help picking from your 35,


(post #164758, reply #14 of 43)

I think what we see here is examples of good and bad icf's, and good installations and bad installations of icf's. Make your choice of icf carefully. A flat wall block is the only way to go. That narrows your list of potential blocks considerably. Make sure you get a contractor who has some experience with icf's. If he doesn't, make sure you choose a block company that will send you someone to oversee the operation, making sure to nip potential problems in the bud. Pouring properly is critical. Slump isn't as important as you might think. Having an "S" to slow down the mix from the pump truck tends to work better. Pour no more than 4 or 5 foot increments, as any higher and the hydrostatic pressure will cause blowouts. As far as walls being straight, I've never seen one braced properly that had crooked walls. Crooked walls are either bad blocks or poor installation. It's also a good idea to place steel channel, the kind used as top and bottom plates in steel frame construction, on your top course of blocks. This helps to keep them straight as well. Turnbuckle type bracing also helps tremendously as you can make small adjustments during and immediately after your pour.

My first icf house, I was a skeptic before the pour and a raging advocate afterward. Keep in mind, I'm a framing contractor so advocating icf's is a paradigm shift for me.

Let me stress again, experienced installers and straight wall blocks and everything will go fine.

(post #164758, reply #15 of 43)

OH, nearly forgot. As an icf distributor myself, I would strongly suggest checking out Eco-blocks. They are the most versatile and the easiest to install.

(post #164758, reply #16 of 43)

Really depends, We are biased toward the solid continuous concrete style for this type of application. If the job is small, ICF may not be the most cost effective route, I would cost it out to see first. Check the area for people selling or using different systems. You can check the directory at either or at If you find some, go to the sites and watch them work, some forms take forever, watch them place concrete too. A good block is quick to build with and can withstand 6-7" slump concrete placed at a yard a minute with a boom, and be INTERNALLY vibrated with a real concrete vibrator, not the tapping of a hand. Most blocks don't fit into this category. There are some new blocks that will be marketed this year that will no doubt break the price/performance barrier that is currently driving the market, so if you are still investigating, keep doing your homework. Ian

(post #164758, reply #17 of 43)

I helped measure a house for trusses a few months ago that was built with ICFs. The contractor said the forms kept blowing over, and were hard to keep straight. We measured the foundation, and added up the numbers. The front of the house was 14" wider than the back. (We checked it twice - that's not a mistake)

We had a hell of a time trying to figure out how to do the roof. The guy ended up putting a porch around a large portion of the house to try to hide the fact that it was so out of square.

After that experience, I don't think I'd ever use the things.

(post #164758, reply #18 of 43)

Ron, a house that out of wack was built by a moron. You could probably find people to say "After what I saw on that job, I'll NEVER use roof trusses!"
If that was the norm, nobody would be building with ICFs. Think about it....Joe H

(post #164758, reply #19 of 43)

I'd say that was "normal" for ICF..... As I have said and others before me, ICF installers need to have knowledge of Framing, Concrete, Exterior Finishing, Interior Finishing and a strong emphasis on layout since there is only one chance to get it right. Unfortunately, the simple appearance of ICF's and many of the manufacturers tout them as a new and better way to make money.....Typically the guys that look at that and bite are the ones that can't make money doing ONE of the trades that is required. The Manufacturers lead them on with "it's simply stack and pour" or "snap 'em together and you're done". Some manufacturers offer training, but the training is usually nothing more than a glorified sales boosting class. Half of the guys installing ICF probably don't know how to pull a 3-4-5 etc. So consequently the business is full of flakes....I guess IR12 We used to build log and timber frame homes, the nightmare stories in that business is comparable, just as in any other I guess.

(post #164758, reply #20 of 43)

Dave . FRrom your post I would guess that you know enough to start with a level and square footing. I think that is the most important step to success with Icf. The first ones that I poured were made with 1 1/2" beaded styrofoam and 4" welded wire every 4" they were a nitemare . I don't think I would use the so called post and beam blocks. Use the turn buckle supports even if it "isn't needed". makes the job go easy. Andy , when I figured the cost for my house I looked at stick frame and ply sheething and ICF and concrete the cost was so close I went to the eve with ICF. Whoever used the 2x4 s for bracing try 16ga. metal studs. Mine are 2"x3 5/8" . works great with the 2" foam that I used . As far as window bucks make them with open bottoms ,mucheasier to be shure that the concrete is in place. If your forms require so much rebar that you need pumpmix I would look for a better system. My last pour was 12' tall .we poured in 2' and then 4' lifts the rest of the way. Dropping that distance was not a problem , still had lots of aggregate on top of the lift. we went with a4'' slump first go round and then 5" till we got to the top . Ian , Name some names of the best ICF s In your Oppinion. I liked the panel form that I used but when I run out of ties I will go to blocks , So have to know straight from the master. Don't be shy tell us what is the best . Also maybe some you would not use again names or type. What is the name of the new blocks that you hinted on?

(post #164758, reply #21 of 43)

Joe -

You're right, in a way. What scared me most about them wasn't so much how badly it turned out, but how difficult the builder said working with them was. He constantly had problems with forms blowing over, among other things. The whole system looked like crap to me.

I'm not sure I would say the guy was a moron, but he sure didn't have a clue what he was doing with the ICFs.

(post #164758, reply #22 of 43)

It is really strange that not a name good or bad is being mentioned....

near the stream needing the names too,


(post #164758, reply #23 of 43)

AJ, I'll mention names. I used Eco-Block, and I've seen Jeff Preble's ThermaWall installed, and I'd use either one. I chose Eco-Block because the distributor, A.H. Harris in, I think, Southington, CT, offered great local support (I don't mean to imply that Jeff wouldn't be helpful; I didn't know him when I bought my ICFs, but I wouldn't hesitate to work with him now). Harris has locations throughout the northeast, so I'd guess there's a branch in Albany that might supply you. Harris's salesman, Gerry Robinson, even spent several evenings helping Pat and me to get started. Based on that experience, I don't think which ICF brand you choose is as important as choosing one that has local people who will support you.

And I've got to comment - An ICF house that differs 14 in. from one end to the other was likely built by a crew that wouldn't have gotten a framed house much closer. That kind of error has to start at the footings, and I doubt the fault lies with the ICFs. Our foundation, admittedly a simple rectangle, was dead level and within 1/4 in. on the diagonals. It ain't rocket science, but like any aspect of building, using ICFs requires common sense and care. Clearly, construction experience is needed, as well.

I can imagine ICFs being difficult to assemble in the wind, but I would think that a properly-built scaffold/bracing system and some strapping tape would hold most walls together in most conditions. I had so much fun building my basement with ICFs that I'd like to try a full house. Because there are no heavy exterior walls to lift, I think that it's an ideal way for small crews to build.

Hope your Christmas was great.


(post #164758, reply #24 of 43)

I'm currently less than half way through having a custom 3200 square foot, total ICF home constructed. I specified an ICF flooring system for both floors (2 story house) - LITE-DECK - and using 6" core Reward Wall system walls. My experience on this project has been that the actual construction is not that difficult, but, attention to detail is definitely called for.

As the home owner, I haven't done much of the work, but I sure have caught a lot of the potentially exspensive mistakes: wrong sized window bucks in the wrong openings, dryer and vetilation wall perforations not made, floor beams mis-alligned. Again, attention to detail and experience can not be over emphasized. Once it's cast in concrete, mistakes are more or less permanent or expensive to fix.

One potential problem with ICF construction, which I've experienced, is that some subs will attempt to charge you more because their unfamiliar with this type of construction.

(post #164758, reply #25 of 43)

O.K. Here is a current OPINION on which ones are good ALL AROUND.
Put these issues aside:

Cost of the block itself, but rely on labor, that is where we make or break a project.

Manufacturer or distributor provided assistance, we have trained more than our share of them.

There are uses for nearly every brand of block, they all perform well if common sense and general experience is used.

For habitable structures, we are biased toward the solid monolithic thickness style block, that being a generic 4, 6, 8, 10 etc, concrete wall. E. Green block, AMVIC, Blue Manx (which is now called ARXX),CO, Formtech, Quad-Lock, Conform, Lie-form,

For sound walls, fence walls and DECORATIVE walls, that are not retaining any significant load, we use the above but consider the screen grid and waffle style.

Screen Grid blocks like Conform Standard, Modulock, Reddi-Form, Rastra and Durisol.

Waffle systems that we consider are only one, that is REWARD. We have not used the other brands for over three years.

We install whatever we are asked to... except for a few. There is a price for all of them.

Ultimately, we use the brand of block that the builder or owner want. If they are trying to cut the cost, then we work with them on that. Most of the time, they leave the decision up to us after they have narrowed the choices. We look at the total installed estimate with emphasis on:
labor liability
time to deliver a good finished product
additional materials required to obtain #2
"Pucker factor" associated with the form system
Ability to fill the forms with 6-7" slump concrete
Ability to place concrete at 1 CUYD per minute
Ability to INTERNALLY vibrate the concrete
Ability of the form to hold 4' of concrete without deflection
Labor factor for putting forms together then moving them about the site
Labor factor for "building" corners
Additional bracing requirements from a base figure
Simplicity of cutting forms both vertically and horizontally through webs etc.
Waste factor of form system-- costs us time to bag and stack it up as well as creates messy site conditions.

With those items in mind, we look for a system that has ties or webs that are close enough together that supplemental bracing is not required at all at any point on the formed wall, to include NO wood bracing around window and doors, No pieces of plywood to "hold cut pieces together", No wood plates on the footing to hold the bottom block from bulging, no wood at the top of the wall to keep the block from bulging. Basically, we don't want to put labor and $$ into something that is not necessary with the right product.

The fact that the ties or webs are close together allows us to utilize ALL of the block. Systems with web spacing at 8" or 12" simply waste a ton of money. We use even pieces of block that are as little as 2" whether it has a web or not, with blocks such as AMVIC, GREENBLOCK and QUAD-LOCK. The webs must not impede the flow of concrete through them and must be easily cut horizontally for around openings.

For the most part, the cost difference between already assembled or molded together blocks vs. the assemble on site block is typically not enough to go the assemble on site rout. The assemble on site blocks are the only choice when a concrete thickness greater than 8" is needed though. The already assembled block are typically landed on the site at the same or similar cost. A house that we put up in Colorado last summer is a prime example: We were 1 hour away from Colorado Springs, the location that Formtech uses for making panels, we used their 14" concrete thickness for the stepped portion of the basement so that we had a ledge for stone, and used AMVIC's 6" concrete form above...which was manufactured in Toronto, Canada. The AMVIC block cost landed $2.83/SF, the FORMTECH landed cost $3.25/SF and we lost three days while they got the ties straightened out (missent the wrong ties not once, but twice) The notion that a few high school kids can put the assemble on site block together is flawed, especially since all it takes is ONE mistake to ruin the day later on. We are professionals, not high school kids. If the builder or owner want to assemble them, that is fine, they then need to put them in bundles that we can move around the site as we see fit. It is easy for one man to pick up a fifteen block bundle, but if they are all loose, the most that can be picked up and carried around site safely is about 4, that just added three times the labor to move blocks to locations they are to be used.

Premade 90 and 45 degree corner blocks are also a factor. The systems that don't have a simple method that doesn't require more time to put together a corner than a straight wall are lacking. Our average project seems to always have over 20 corners, usually a third of those are 45 degrees. Site cutting foam to obtain an exact 45 degree corner ten or twelve foot tall is no fast task unless jigs are used and additional bracing etc is used which translates to more unnecessary cost.

When forming walls over large openings,(lintel) the requirement for additional reinforcing is usually dictated, typically stirrups should be used with larger horizontal bar. The ties don't usually cause much grief here since the lintel design that we implement is detailed with the condition at hand. We make our stirrups on site. Placing concrete in the wall however is another consideration with the added reinforcing along with the ties, therefore, it is our choice to INTERNALLY vibrate all concrete. Most ICF manufacturers don't advocate vibrating internally....mainly since the form system won't withstand the added pressure. The idea that simply tapping the wall with a hand or using a sander or sawzall to vibrate is flawed for consolidating concrete although it makes the people on the job feel good.

The ability for the contractor to control the slump of the concrete is non-existent in residential construction (with some exceptions of course) That is why it is necessary to use a form system that withstands a placement rate of a yard a minute. Depending on weather conditions (and other factors), the ability for the mixer driver to maintain the correct slump is nearly impossible. Most ICF form systems are poured so SLOWLY that it takes an hour to discharge a ten yard truck....No way can there be any consistency in assuring the concrete does not have voids as a result of the slump of the concrete unless every bit of it is vibrated in the form. Not to mention that some ready mix companies won't send trucks to ICF jobs until the previous truck is empty, or else they send them all at once thus causing a mess. Tapping the exterior of the form system does no good in knocking the hanging concrete down in the form. Concrete builds up on ties and reinforcing as each pass around the building is made, causing the wall width to shrink, much like rust in a pipe or fat in arteries, We have seen an ICF project where 80% of the walls did not even have concrete at the bottom, also, we have seen where the top was "full" yet less than a foot below (typically where horizontal bar was supported by ties) there were massive voids, a combination of concrete build-up as a result of several lift passes, and concrete that was no doubt of the wrong slump. Voids are common in ICF walls on projects that we stop to "compare our work". The last one we stopped and "tapped for voids" had 22 voids!! In one area, the electrician ran his wire through a void!

In short, the smaller tie spacing, (yet not too constrictive) the lower waste factor, the sturdier the wall, the easier to use, lower deflection, the straighter the wall will be, the corners will be "more true" with premade units.

We own our bracing system, we use the WASS (Wall Alignment Scaffold System) system with some modifications. It is versatile and useable with just about any ICF system. It is OSHA approved if put up in accordance with them. We believe that all we should need to bring to the job is WASS for all wall alignment and scaffold. We also believe that the form system should do the job of containing the concrete. Systems like AMVIC and GREENBLOCK do this repeatedly without fail. We also believe in "if they say one, we'll do two". We err on the side of conservative, so we set our bracing at 6-7' centers, this helps us out considerably in ways I won't discuss here. We stringline every wall and strive to have the wall as straight as the string. With the WASS system, we use regular form turnbuckles, so tweaking the wall is easy.

Our AVERAGE project above grade is a single story house, two or three plate heights, hardly ever 8' tall, usually 9 or 10 up to 14 or 16'. The average formed wall square footage is 2500SF, the average number of corners is 25-35, the average number of openings is 25-35 (1000SF additional wall area). Lately we have been incorporating a saferoom with a steel frame and door, and a 6" concrete slab ceiling all poured with the walls. We typically have all materials on site before we arrive. We use 3, 4 and 5 man crews, depending on the project. Most projects are completed start to finish in less than 4 days. The average reinforcing is #4 bar 16" on center horizontally, and #5 bar 12" on center vertically-double bars around all openings, and lintels over 4' wide have stirrups at d/2.

If we use a boom pump to place the concrete, we try to place the concrete at a yard a minute with a lift height of 4-5 foot depending on the quality of the slab or footing that we are pouring on. If we are using a line pump, we usually try to place concrete at 3 minutes per yard (line pumps are slower)

The success of an ICF project is helped by several factors that can be detected early on:

slab or footing level within 1/4". Not only over the perimeter, but from the outside edge of the wall to the inside. The wall will want to lean with the weight of the concrete to the perpendicular. If the slab is way out of level, then we shim the block and pour a small lift to set the shimmed block in place, by the time we get back, the concrete rarely leans the wall out.

The slab or footing is the right size and square with the Reinforcing Dowels set correctly. All too often, we get to the job and the slab or footing is WAY off...

The walls are engineered by a P.E. (P is for plenty and E is for extra)

All wall penetrations and changes are marked on OUR set of plans and we have details for connections, beam pockets etc..

We often provide the framing along with ICF, especially on two story projects. By adding the framing as an option, we eliminate having to pull off the job and come back. Most of the time, framers ADD for ICF (which I don't blame them after seeing the poor general quality of ICF installs), so we can offer the service to eliminate one trade's learning curve add-on.

ICF walls are only one small piece of the building "puzzle", if ICF is going to be used for the exterior walls, then energy efficient and durable products should be used to complement the walls throughout the structure, otherwise, the walls alone aren't worth it unless the customer "just want it"

(post #164758, reply #26 of 43)

When's your book coming out? (I'm printing your post above to pass around our company.)
A year or so ago, I read one of your postings at in which you said, among other things, you thought Integra Spec was one of the better systems you had worked with to that point. You haven't mentioned it above. Have you changed your mind about that product. I'd appreciate your opinion because I have a price out on a large Integra Spec project and have never worked with it before. I ahve built with Lite Form and Blue Maxx.

(post #164758, reply #27 of 43)

Well wouldn't you know it, the publishers turned down my book....seems I had too many run on sentences and I put all of the periods in the wrong places......

To answer your question about Integra Spec...

After I made that post, I thought about the potential problems with that system on a more complicated project and have not really felt comfortable with it. Furthermore, we tried the AMVIC system.

We have to deal with a lot of out-of-level footings and slab edges, and since the panels float freely from the ties, I think it is going to be tough to eliminate the "banana effect" where the wall bows vertically like a banana on end. We also had to install bracing around the interior and exterior of the openings to keep the form from bulging where it was cut. The form is also an assemble on site that I feel doesn't make it cost wise. Initially, Integra Spec was priced much lower. If they added the extra tie in the panels and decreased the spacing to 6" on center, then it would be a good contender. I would use it vs. assembling lite form any day. Blue maxx is just too cumbersome and they still have quality problems. If you have the opportunity to grasp the end of a BM block and pull it apart as if your hands are the concrete, you will find very little resistance, couple this with the fact that on the average job the bundles don't get handled with the utmost care...this usually leads to suprises at concrete time. For comparison to the pull apart on BM, try the same thing with Integra Spec and with AMVIC.... Unless you really snap at the start of the pull, the only one that survives is the AMVIC...Do the same with GreenBlock, it won't break. Another thing about the Integraspec that seems like it should work well but doesn't is that it doesn't want to stay straight, possibly due to the play of the tie, whereas the solid prebuilt blocks will tend to stay straight. Opinion only...of course.

(post #164758, reply #28 of 43)

I was really suprised to see all of the negative feedback at the begining of this thread. The fact that people mention walls out of plumb/square are simply the result of poor installation. The same as it would be with any other building system in the hands of inexperienced people. There is simply no excuse of out of plumb or out of square walls.

I have been installing ICF's for a few years now and have used several different brands. Some I like, some I don't, some were easy, some were hard, some were fast, some were slow. It took some experience and projects under my belt before I could sort through all of the brands available. Time to complete an ICF home should be virtually the same as a stick frame home, if not faster. The stories posted above about taking months to complete could not possibly be from experience ICF installers. By example an average residential project should take under a week. I recently trained a do it yourselfer on a 7000 sq. ft. basement with 10' walls. The crew was the owner, his wife and three kids (12,8,5). We started the project on Monday and was poured and completed by 3pm Friday. The walls were as straight as the string line we had around the perimeter (straighter than is possible with wood). Also, last year we completed a 10 story building using ICF's. The building was 11,000 sq. ft. per floor or 110,000 sq. ft. total. Wall heights varied between 9' and 11'. The building had 96 45 degree corners per floor and only 6 90 degree corners, the longest straight section of wall was 10' (very cut up). Total time from start to finish was 90 days. (one small photo of the building on my home page

So, in short, ICF's are a very viable and efficient building system when in the hands of an experienced installer. Walls can be straigher than stick frame and durability, strength and energy efficiency can't be matched by any other building system.

(post #164758, reply #29 of 43)

Thank you, Ian. If the man signs on the line, I'd be delighted to build his townhouses, of course, whether in Integra Spec or in cow poop if the price is right.
So a few more screws through the bracing don't take care of the wall bowing do they? Damn, I hope we won't have to start crowning ICF blocks as they go up.

(post #164758, reply #30 of 43)

I have been following this discussion since early on, and have learned a lot. I have an upcoming project for myself that I would love to do in ICF's. It is a two-story building, about 900 sf per floor, shop under office.

I'm in Southern CA, and the considerations that matter most here for this project include termites, seismic codes, noise control, fire resistance. A good friend used Cempo screen grid type panels for a foundation last year and liked it pretty well. I am leaning toward the block style that gives a monolithic concrete wall between foam skins, however, and so am curious if blocks of this kind are available made of the Portland cement bonded EPS beads? Our climate here is very mild, so extreme insulation is not really needed. The termite factor is a critical factor in my situation (am replacing a 1951 structure with extensive damage), and I also like being able to plaster both faces without metal lath. Do the manufacturers of ICF's typically offer engineering services in seismic areas? I would like to take it to the rafters. We are close by a freeway that never abates, and the office may one day become living space. Thanks for all the good posts.


P.S. Like Ian said, I really would prefer a wall system that can withstand internal vibration and 4' lifts. Does one form a two story structure from the footer in increments with separate pours, or all at once?