Great looking project. Should be a contender for an ICFA Award.

It is a beautiful home and a huge ICF/InsulDeck project. It does go a long way to show the right ICF contractor either makes or breaks a project. It can either be ones dream house or it becomes a house of horrors. ICF is specialized trade and it's not like wood frame where mistakes can be fixed with a hammer.

Keep us updated!

How many different days did the pump truck have to come out? I guess that is the same as asking how many lifts there were and did they use a pump truck for every one?

There were 5 pours for the ICF:
1) 1st floor walls
2) Floor between 1st and 2nd
3) 2nd floor walls
4) Attic floor
5) Tower and attic knee wall

All the pours involved a pump truck.  Even the foundation slab used a pump truck.  Given the size of the project, I don't think it would have been practical to do it any other way.  I didn't time the truck hours, but I think all the pours were between about 4 and 6 hours. 

The only portion that didn't use a pump were the foundation piers.  The foundation sub poured all 98 of those directly from the concrete truck.

If you don't mind wasting 9 minutes and 23 seconds of your life that you will never get back, I put up a video here:

http://www.youtube.com/watch?v=lP_G...e=youtu.be

It took about 1 month for the foundation, and 2 1/2 months from start to finish for the ICF.

Thanks for all the positive feedback.

Oh, that's right: no footings. They were piers.

What about the main floor slabs (the first floor floor)?

Posted By ICFBdr on 02 May 2013 10:14 AM
Great looking project. Should be a contender for an ICFA Award.

I agree. You should enter. This is a perfect example of an ICF & InsulDeck project done right.

Posted By ICFHybrid on 03 May 2013 12:57 AM
Oh, that's right: no footings. They were piers.

What about the main floor slabs (the first floor floor)?

The main floor slab was done with a pump truck.  That makes a total of 6 pump truck visits for the house. 

The piers were done directly from the concrete truck (no pump).  They pour the concrete into each pier immediately after drilling (98 piers done over a 4 day period)  I'm sure they try to avoid the pump if at all possible for the piers, just due to the time involved in the drilling process.  The video above shows the pier and slab process, if you haven't checked it out already.

One thing that I have noticed, is that there has only been a single 4ft hairline crack in the entire foundation slab.  That crack was there the day after the pour, and not a single additional crack has showed up since they post-tensioned the slab.  The insuldeck is another story.  There are a number (dozens) of hairline  cracks (nothing at all structural) that show up within 1-2 days of each pour.  I'm guessing it is from a combination of slight settling in the deck (the engineer had warned me to expect 3/4 up to 1" of settling in the longer spans) and the different concrete mix (pea gravel and higher slump/more shrinkage) to better consolidate with all the beam rebar. 

I'm sure that when we start taking down the shoring this coming week, that there will be some additional settling in the floors.  I'd actually like it to settle as much as possible over the next few months (before I put tile down).

(dozens) of hairline cracks

I got about 2-4 such cracks per room within a few days of the pour. Hairline cracks continued to appear for months or even longer, probably precipitated by understandable stresses in the concrete. Here are some stresses that appeared to facilitate cracking in my slab overs;

1. Continued construction of upper levels including placing of interior walls.
2. The first hard freeze of some duration.
3. Really thorough drying and exposure to sun during a long summer dry spell.
4. Turning on the hydronic heat and bringing it up to temp (18 mo after pouring floor)

Ultimately, I ended up with maybe 4-8 cracks per "room"

I have had lots of thoughts about the cracking, mostly centered around how they affect the structure, but in the long run, I haven't retained too much anxiety over it. I saw in some of your pictures where it appeared as if the contractor cut down (up) into the forms for the bracing walls. What was that for? We used 2X6 studwalls in which they production cut the studs and sorted the ones that turned out longer to the middle of the span in order to create a bit of an "arch" in the bracing. In retrospect, I realize that isn't going to get you a perfectly level floor above unless you take care to continue the "arching" through to the finished concrete surface above.

We are now laying tile and there is a definite rise in the surface towards the edge of each slab. Can't really tell if it is from settling of the slab or by power troweling during the initial finishing.

A couple thoughts on flooring:

1) Use of a crack isolation membrane under tile is a must. We are using Schluter Ditra. Thorough "mapping" of the floor high and low spots by crawling around feeling with your hands and a bubble level prior to installing the Ditra helps you find where to lay the thinset a little heavier or a little lighter as the first step in reducing the inevitable irregularities on your way to a flat floor.

2) While scrubbing the floor of all the construction grime prior to starting the Ditra, I noticed the very beautiful "grain" of the concrete aggregate appeared once again. Finishing these floors by staining and polishing the concrete appears to be quite viable. At least one person remarked that the cracking prevented that, but I have noticed that the most beautiful concrete stained floors are the ones that utilize the cracks as part of the decoration. Perfect floors with straight control joints appear, well, too perfect. I have seen the best finishers work the color and polish in such a way that the cracks appear to be a part of the natural material. THey are the most believable floors. Staining and polishing the concrete would be a very cost-effective and tremendously energy efficient finish to a radiant slab over.

Interesting to note that the engineer calculated 3/4" - 1" of creep on the floors. I figured it would be less than that but those are large spans. The interior stud wall framing should take that into consideration so as to not crush your top and bottom plates while the floor settles.

ICF walls provide the perfect curing environment being sandwiched between the EPS but InsulDeck slab floors are a different story. As mentioned, the cracks are aesthetic and do not compromise the strength unless the crack gets large enough to where it might need to be inspected.

Concrete cracks, that's part of its nature but can anything be done to reduce these cracks?

I've read that fiber additives can help although they leave the top slab somewhat "hairy" but that can be sanded off. Curing exposed slabs is not easy since it's "exposed" and weather dependent. Wind, heat, sun, all of which can accelerate curing.

I have noticed that higher psi ratings usually have fewer cracks. A 3,000psi mix vs. a 5,000psi mix results in less cracking.

Out here in Phx about 80% of the new homes have post tension slabs to prevent major cracks. The homes that were slab on grade, with no post tension, they ALL develop significant cracks resulting in buckled and cracked tiles and other problems. To prevent these problems, builders are now doing post-tension on 8 out of 10 homes. My current home is post tension and I don't have any cracking. My other home was NOT post-tension and the slab cracked and lifted up causing a 3/4" lip.

I am wondering if it would be cost effective to do post-tension on InsulDeck to prevent the cracking?

The interior stud wall framing should take that into consideration so as to not crush your top and bottom plates while the floor settles.

My biggest unsupported spans were about 20', but I saw no evidence whatsoever of pressure against the lower studwalls. Presumably, you would see some compression of the foam where it bore down on the top plate of the walls, but I never detected anything like that.
Since the cracks clearly don't affect the slab integrity, I really don't see any purpose in efforts to stop them.

I go to the big box stores often, HD, Lowes, and I never see cracks in their floors. What do they use? Also, would adding Helix prevent cracks? How much does helix cost?

Posted By ICFHybrid on 04 May 2013 07:01 PM

The interior stud wall framing should take that into consideration so as to not crush your top and bottom plates while the floor settles.

My biggest unsupported spans were about 20', but I saw no evidence whatsoever of pressure against the lower studwalls. Presumably, you would see some compression of the foam where it bore down on the top plate of the walls, but I never detected anything like that.
Since the cracks clearly don't affect the slab integrity, I really don't see any purpose in efforts to stop them.

I meant that creep is a factor that must be considered into the interior wall assemblies. If the engineer says 1" of creep then that means the upper floor can drop by 1" and if you didnt take that into consideration then it can crush your wood framed walls. Its easy to do by just leaving a 1" gap on the top plate when framing the walls.

Posted By robinnc on 04 May 2013 07:20 PM
I go to the big box stores often, HD, Lowes, and I never see cracks in their floors. What do they use? Also, would adding Helix prevent cracks? How much does helix cost?

Good observation. I just came from Costco and I don't remember seeing any cracks. Maybe they use a special mix? I was quoted $4 more per yard for fiber reinforcement. That is the claim of fiber reinforcement, that it helps prevent cracks.

Here is an engineering article on fiber reinforcement:
Bright Hub Engineering

I am not sure what the equation is for InsulDeck floor slabs. Let's say a 10" form? Anyone know the equation for InsulDeck?

I know with a 6" ICF wall, it's basically the wall square footage divided by 54 = yards of concrete needed.

So to price it out for my area, a 3,000sqft wall area with a 6" core requires 56 yards of concrete.

56 yards of concrete @ $82 a yard for 3,000psi mix = $4,592
56 yards of concrete @ $88 a yard for 4,000psi mix = $4,928
56 yards of concrete @ $88 a yard for 5,000psi mix = $5,264

Fiber reinforcement adds $4 per yard to the total or only $224 It's not that much money ($224) for fiber reinforcement. The question is WHAT KIND do they use?

I also don't see the cost savings in going with the lesser psi mix. We are talking about $672 for the entire wall pour with the 3,000psi vs 5,000psi

I've read where they were doing an ICF wall and instead of adding more rebar the engineer on record decided to add fiber to the concrete mix. Supposedly the fiber replaced a lot of the rebar and the engineer OK'd it. This would tell me that the fiber reinforcement does add a structural or tension load to the concrete.

Posted By robinnc on 04 May 2013 07:20 PM
I go to the big box stores often, HD, Lowes, and I never see cracks in their floors. What do they use? Also, would adding Helix prevent cracks? How much does helix cost?

Proper prep of the base. Fibre reinforcement (usually poly fibres. And no they don't fuzz the surface. Metal filings at the surface can react with floor finishes and cause staining.) Water reducing admix. Simple recipe.
Spider cracks are almost always to much water. Even with frost (not a good think) its still to much water.
Hair line cracks are usually shifting, lack of support. i,e, if you pour over a wood floor or q-deck the hair line crack will almost always be over a beam because the spans flex.
Larger cracks are almost always shrinkage. Also often a case of to much water however concrete likes to break into about 20 x 20 squares. That is why most engineers spec saw cuts or control joints in a twenty by twenty pattern. Anything that will hold the concrete such as a post or wall should be looked at when deciding where to cut. Any oblong section should be cut square. All soft cuts should be done as soon as the concrete is cuttable. Usually in under 24 hours. The saw cuts are to relieve the shrinkage pressure and control where the slab will crack.

go to the big box stores often, HD, Lowes, and I never see cracks in their floors

They have slabs on ground, not slab over. If you look, you will see they most often have control joints.

Posted By ICFHybrid on 04 May 2013 10:00 AM 


Use of a crack isolation membrane under tile is a must. We are using Schluter Ditra. Thorough "mapping" of the floor high and low spots by crawling around feeling with your hands and a bubble level prior to installing the Ditra helps you find where to lay the thinset a little heavier or a little lighter as the first step in reducing the inevitable irregularities on your way to a flat floor.

I have the Schluter Ditra for the outdoor decks (for waterproofing as well as crack isolation).  I need to get the decks waterproofed as part of the Dry-In process for the house.  I was going to wait till the end to do the interior tile floors (let the rebar and concrete find a happy medium between tension and compression).  I wasn't sure if the crack isolation membrane would be required, or if just a modified mortar and grout would be sufficient if the floors were given enough time to settle first.  I have some time to think about it and will see what the tile guy I eventually pick out recommends.

Although there is the hairline cracking in the insuldeck, it doesn't really bother me.  With as much rebar and concrete that went into this house, I'm not worried about any structural issues.  I think both the engineer and ICF sub made sure that this thing would be around for a while. 

Posted By ICFHybrid on 04 May 2013 10:00 AM 

I saw in some of your pictures where it appeared as if the contractor cut down (up) into the forms for the bracing walls. What was that for?

I'm not sure what you are referring to there.  The engineer did put some camber (3/4 to 1") in the longer spans.  This allows for settling / creep to flatten out the floors.  That might be what you saw.

This allows for settling / creep to flatten out the floors.

That might give you level ceilings, but unless they troweled a camber into the upper finished surface as well, that floor will end up having concavity on top as it settles.

I saw some of your pictures where the wood supports seemed to be supporting the upper forms which had notches cut into them.

ETA: It's the last image (bottom, right) in the four dated 10 Apr 2013 04:46 AM.  Can't tell if it is the perspective caused by the top plates projecting out or if the support bracing is let into the forms on top.

Posted By ICFHybrid on 05 May 2013 12:12 PM

This allows for settling / creep to flatten out the floors.

That might give you level ceilings, but unless they troweled a camber into the upper finished surface as well, that floor will end up having concavity on top as it settles.

I saw some of your pictures where the wood supports seemed to be supporting the upper forms which had notches cut into them.

ETA: It's the last image (bottom, right) in the four dated 10 Apr 2013 04:46 AM.  Can't tell if it is the perspective caused by the top plates projecting out or if the support bracing is let into the forms on top.

I see what you are saying with the camber.  It is probably something I wouldn't even notice.  I'm not that sensitive to minor elevation changes.  I might keep a eye on the amount of drop over the next few months with a laser distance device (accurate to 1/32") just for fun.

It is just an illusion in that picture. The support bracing came out further than the insuldeck in the photo, so it just looked that way. The insuldeck was laid directly on top of the support, no cutting involved.

Posted By ICFHybrid on 05 May 2013 12:12 PM

This allows for settling / creep to flatten out the floors.

That might give you level ceilings, but unless they troweled a camber into the upper finished surface as well, that floor will end up having concavity on top as it settles.

I've seen the odd finisher that could put a hump in the floor but usually it wasn't intentional (;=)). On the other hand, the "puddle" created when the slab goes into torsion is pretty easy to fix with a dozen or so bags of self levelling cement. 3/4" drop on a twenty foot span might not sound like much but it's still 3/4" out of level in ten feet. That would drive many people nuts when the furniture etc. is placed.

That would drive many people nuts when the furniture etc. is placed.

Won't you have visible or functional issues with laying flooring before you get to occupying it? Like, what would a floating wood floor do over a 3/4" depression?

Posted By ICFHybrid on 06 May 2013 03:28 PM

Won't you have visible or functional issues with laying flooring before you get to occupying it? Like, what would a floating wood floor do over a 3/4" depression?

Wood floors have creep also, while there is a lot more dead weight with concrete floors over a 25' span, that is why engineers take into account the creep of a floor.

I wouldn't worry about it and like I mentioned, when framing the interior wood wall underneath it, take that creep into account and all will be well.