I was reading through Owens Corning Fold Form manual and read a blip about form settling, "1/4"-1/2" in 8 feet can occur", is this common with ICF's in general?
And how often in a typical house does it happen, as in a 40' long wall if it settles does it typically settle uniform or is the top of the wall wavy?

Settling can be an issue on different levels with different blocks and is contributed by different items such as amount of steel, density of foam and how you pour.

1/2" is a lot for 8'

on your 40' wall I would expect maybe 1/8" max.

Some settlement is normal with ICFs. The amount depends on the type of block, how tightly they lock up, how good a job you do at locking the blocks together, and other factors mentioned by Chris. If you look at the vertical posts of a bracing system, you will see that the screw holes are slotted, to accommodate this. Generally, this will be consistant over the entire wall, and should not cause any practical problems. As Chris said, 1/8 to 1/4" would be the most I would expect on well set wall.
FYI, I used one brand of forms that did not lock together. The foam was square edged, and depended on the composite clips to hold them in alignment. Before the pour, you could see daylight between the forms. We were greatly concerned, but the mfg assured us that it would be OK. And as the weight of the concrete pressed down on the steel, the forms magically settled tightly together and we didn't loose a tea cup's worth of concrete out of the forms.

We refer to this as settling. This was a major issue fifteen years ago. When horizontal rebar is placed in the forms and then concrete is poured in on top of this bar it creates a large downward force. This force caused compression of the forms. One of the brands had compression in excess of 1/8" per course of block. Worse yet ,the block was only 9 7/8" tall.On an 8'-2 3/4" basement stack,your finish height after pour ,would be 8'-1 1/2". You lost an inch and a quarter in wall height. Many people ,who did not understand what was happening, claimed that the block was "floating "or" lifting" this was not the case. These contractors or DIY's were lacking this understanding. They would use bracing that had fixed attachment to the block. The block could not move. When this wall was poured with this type of bracing,severe alligatoring, would develope . This alligatoring would of course be more noticable at the tpo of the wall. It was so bad that I have witnessed concrete pouring out from between the upper courses.Many people to this day, dispel
this principle. My question to them is ,if your bacing is still attached to the block, and your brace has not changed in height, what happened? The deer in the head lights stare usually follows,or an argument. There are still many well known and often used products that behave this way ,but to a much lessor degree than mentioned above. Brands can make a big difference.Integraspec was the first to solve this problem. Their webs attach with a hook ( looks like the end of a knitting needle) to each other vertically. their web also floats in a track that does not allow vertcal loading to effect the foam sides of thier forms.Some mfg's have tried to copy this .Theirs do not work quite as well ,because the side walls of thier forms are attached to thier web.Many other mfg's have lengthened their strapping ,studs,which inturn ,reduces the amount of foam compression that can take place.Manufactures that limit their pour height,usually have greater compression . By limiting pour height ,you limit loading to fewer courses of block. By the time you make your second pass the curing process has limited this problem,the third pass and so on. This also helps to explain why ,if the footing, has a dip in it ,it would show up at the top of your wall. The forms compressed to match the footing. If you have doors and window openings your compression changes and could cause humps in your wall at these areas. Stacking blocks one @ a time, is more complex than it may sound.

You are wright about the compression facts, However by using a laser level eliminates all of these problems does it not?

thagreen,

Please explain, thanks!


Stacking one block @ a time!

Thagreen, yes if you have perfect footings and you dont over-tighten the screws in a slotted brace/alignment you should get even settlement from pouring somewhat even lift heights. There is one well know ICF form that settles more in their corners than their straight block, but I woudn't dare to elaborate other than telling you it's not a reversible form.

Dave

So what do you guys do if you have uneven form settling, shim a top plate or grout a top plate level or what?

We have limited this problem, because we have aligned ourselves with products that do not have settling. Proper bracing is also important to succesful results.

To answer your question though, you can use a laser level or a transit to assure that the top of your concrete pour is level by skreeding. So you don't have to do either if you have done it properly in the first place. If you have already poured and gotten this result and the concrete is cured, then you should shim.

The thing to keep in mind is that if you are going to have any settling, that you need to compensate for it above the doors and windows prior to pour, because if you don't, the settling won't be in those areas, but will be on the rest of the walls. This un-uniformity will look like a hump in the wall, and will be magnified as you go up more courses. You need to leave a gap on the top side of the window and door bucks based upon the amount of settling that you anticipate. It is not unusual for the gap to be 1/2 to 3/4 of an inch.

To thagreen,

The laser level will not solve compression or settling. It will, though, allow your finished concrete surface to be level, which is important on your highest wall.


Stacking one block @ a time!

So Chris says 1/8" max, Wes says 1/8"-1/4" and Chirp says 1/2" to 3/4". Quite a range; 1/8" I could live with, 1/4" is pushing it but 1/2" or 3/4"??

Thats no good, you cant assume its going to be uniform.

Anything under a 1/4" on 40' is first off within acceptable tolerances (Construction Standards) and secondly not noticeable once all construction is complete.

Larger than 1/4" will require shiming to fix the issue. Using a laser to check and screed could work...if you have the manpower on site and also provided you haven't had to set all the hardware prior to pour.

Floating is another issue that happens with certain blocks. But that's another thread.

The 1/2 to 3/4 would be with an inferior form or pouring the whole 8' as a rookie in one lift. As long as you follow the recommendations above you should be no more than an 1/8th. There are many reasons they settle as described above including wet slumps, and to much lift height. Compression around windows and doors are also affected by your methods of pouring.

As long as your asking these questions it tells us you want to be informed! Consult your local dist. how your specific form re-acts to vertical pressure along with the bracing and see what they say. If they seem stumped maybe they don't know that much about settling. Or they use one of the less settling forms, but there's always dissandvantages with them also.

Dave

Chris, you where suppose to call me with your cell phone # quite a while ago? Or maybe Email me! Hope you had fun at WOC while I shoveled another 12" of a 150" snow year. I know if I was as smart as you I would have moved away from the cold as you did many years ago. I'm not quite sure why they let a canook into the US thou, other than learning a few drinking lessons. LOL

Dave

Jealous Dave?

I can't call you...I was at the bar one night and some girl named Lola wanted my number...I gave her your card...so if you get a call...

A couple of years back I had a home owner using a laser transit on a foundation that had about 3/16 of settling. He was pissed and threatened not to pay the remainder of the bid. But in most cases its not that big of a deal. Like mentioned if you use a good block it should be minimal. This is one reason I am hooked on the vertical system because settling is eliminated.

Sound like he was LOOKING for any excuse to try to not pay a bill, maybe so he could pay for surgery to have an object removed from his........
hahaha

chirpfrog,
Laser level is a spinning laser on a tripod which seeks the laser receiver. Unless someone knocks over the tripod or moves the receiver on the stick all top of wall will be the same.
The height of walls must be close to what it's supposed to (blocks), but this helps a great deal if the foot. is uneven or out of plumb. A spot check at t/w is good practice so you know what to expect. One guy on the pump and the other, directly behind, floating w/laser to 1/8 or less of expected height. Hope this clarifies.
Cheers!

Thagreen,

You left a guy out. The one running the vibrator between the pump guy and the float guy!

BNC

If you put more time in your footing and get em done like a sidewalk you will be alright, leave 3/8 inch or so over your doors and windows and bring your lifts up uniform (same depth every pass) have someone walk with the pumper with a long gauge stick on first pass) Some like Nudura have continuous ties that meet so it will not settle, Throw away the pink stuff #1!

I suggest that you do a little research before coming to too many conclusions.  There are some block out on the market that do allow quite a bit of settling (1/2" - 3/4").  There are some others that saw that problem and fixed it.  I do know Integraspec's webs connect and so does Nudura.  I don't know much about other block.  Another cool thing about Nudura is that they also fully lock so you don't have any lifting during the pour either.  As far as I know, they are the only one on the market that does that.
Hope this helps.