This would be for a residential 2-story home.

My architect had a couple of questions:

1. What is the narrowest section they can grout and reinforce (as in between windows)? 
2. What is the narrowest piece of wall section (or shortest dimension) recommended from corners to window opening?
3. What would be the longest practical header span if one were to build over several window sections with one larger opening?  I realize to some degree that this would depend on depth of wall section above such openings and the max. number of rebars or sizes of rebar permitted in an 11" ICF wall system at the top of the opening for spanning a beam.

Lebear,
1) I've gone down to a couple of inches. However, what really matters here is how the engineer sees it. Most engineers will treat concrete between openings of less than 10 inches or so as if it isn't there. In other words, they will design the lintel over the opening as if the little piece or pieces did not add support.

2) Zero for a decent installer. But again you'll want to run this by your engineer. Most manufacturers guidelines will say a foot or more. If you are not using an engineer for some reason which I do not recommend then stick to the the basic guideline. On a number of occasions I've seen no corner at all - 90 degree lintel over an all glass corner. But don't try without an engineer.

3) The furthest I've gone is 37 feet. I think most pre-engineered tables stop at about 20 feet and that's with a relatively light roof allowable load of 1000 lbs per foot. That's okay for most houses but ... since we're probably only talking a few hundred dollars for review of these scenarios, I would consult an engineer. Regards .

Your architect should read the manufacturers tables to begin with and perhaps take an ICF course

Besides that

I will not try and create a column less than 6", if the column is less than 2' I just pretend it is not there in figuring out the lintel

I have build windows right into the corner and back down the side, an engineer designed the steel column to carry the ICF wall above, house was Frank Lloyd Wright inspired

Even though I say treat any column under 2' as if it doesn't exist, an engineer can make them exist in his calc's, I have never had to exceed 20' clear span

THANKS GUYS!

Where would one find the manufacturers tables? Can that be found on Nudura's website?

They were there, haven't looked in a long time. Your distributor should also be able to give you an install manual and they are all listed in the back.

If you are using the manufacturers tables, as you said Nudura, make sure you are using Nudura block. Not that I think it makes a difference, reinforced concrete is reinforced concrete, the ICF has no structural value, however the inspector may not accept it if you use one companies tables but another companies forms.

You will also find that after reviewing tables from different manufacturers, using the same perimeters the rebar spec can be different...because they use different engineers

See Reinforcing Tables section under Installation Manual Section:

http://www.nudura.com/en/Technical_Centre.aspx

LBear, If you don't want to hire an engineer, use the HUD Prescriptive Method from US Dept of Housing and Urban Development and you will not have a problem with inspectors. Manufacturer's suggestions are just that, suggestions. They will accept no legal liability for those suggestions. Here's a link.

http://polycrete.us/uploads/ICF_Construction_-_HUD_Prescriptive_Method.pdf

Posted By TexasICF on 12 Feb 2012 01:34 PM
See Reinforcing Tables section under Installation Manual Section:

http://www.nudura.com/en/Technical_Centre.aspx

THANKS!

After reviewing the tables, it is safe to say that the home will be best suited for the #4 re-bar @ 16" O.C.
The home will be engineered but judging from everything I have read, I don't see them going any bigger except for maybe #5 horizontal every so often.

TexasICF - Would you say that #4 @ 16" O.C. for a 2-story residential is the "general rule"?

Lbear,
#4 is common but you may mean 16" O.C. Verticals and 18 " O.C. Horizontals if you are considering Nudura. We sometimes see #5s used here also but you will still be much stronger than whatever your neighbors are buildimg with using #4s.

Lbear,
Note the Nudura tables are based on using grade 60 or 60 ksi rebar. Logix, for example, has tables for both grade 40 and 60.

TX ICF,
The Nudura rebar tables show a Wisconsin PE stamp. Does that fly with inspectors in TX/other states as long as you comply with the unshaded areas of the tables?

There is a more recent 2nd edition of the HUD Prescriptive:  http://www.huduser.org/Publications/PDF/icf_2ed.pdf

Farmboy,
Nothing against logix but you should NOT use grade 40 rebar under any circumstances - use only grade 60 or better.

Regarding the stamp; yes they are fine for most inspectors but should not be confused with a state specific stamp which may or may not be required depending on your jurisdiction.

I bought sufficient #4 and #5 a couple years ago, all grade 60. thanks for reinforcing that rebar decision.

No gov't inspection required or available in the unincoroporated areas of our county, so I don't want to get outside the prescriptive if I can help it. Will get engineer to look over plans when they push the envelop. Dave

Why do they state that the 2nd story ICF wall height can only have a MAXIMUM height of only 10 feet?

That would mean that ICF designs cannot exceed 10 feet in wall heights.

It doesn't make sense to me...

The manufacturers tables are based on certain conditions, you would have to read the entire disclosure to see what parameters they have used to give you the information you are reading.

I.E. Nudura tables account for California seismic, but the State of California will not accept the manufacturers tables as they want everything job specific. That being said, I had engineers in California do a review of Nudura's tables, cut and paste on to the project, I also had others disagree and increase the rebar spec and others who reduced it.

You will also note a clause about the building not exceeding I think it says 40x80, again, the engineer who reviewed and stamped these tables has based everything on certain conditions.

This does not mean you cannot use ICF for a footprint bigger than 40x80 or 2nd floor walls cannot exceed 10', it is telling you if you are using the tables to build your house without an independent engineer review that would be job site specific here is what we can tell you works based on limited information and what we assume your conditions are.


What I would like to add is an engineer can actually save you money on your project, use the tables as a guide only. I was in Florida in '05 and the engineer reviewed and stamped drawings for 12' high walls, 6" core with #4 bar at 4' o.c. both directions!! Does it work? Who am I to argue, I get a set of plans and build as per spec. But if you use Nudura's tables from '05 it called for #4 @ 18" o.c.v. and #4 @ 16" o.c.h. for that application...the tables were covering Alaska to Florida and Tijuana to the Baffin Islands, but when rebar was hitting $ 1000.00 per ton, this engineer saved that and then some.


I just finished pricing a job tonight, the plans show 12" ICF below grade, after review and using experience I suggested to the client to have it reviewed, it can be done in 10" and the savings were roughly 15%

Posted By Chris Johnson on 12 Feb 2012 11:28 PM
  But if you use Nudura's tables from '05 it called for #4 @ 18" o.c.v. and #4 @ 16" o.c.h. for that application...the tables were covering Alaska to Florida and Tijuana to the Baffin Islands, but when rebar was hitting $ 1000.00 per ton, this engineer saved that and then some.


I just finished pricing a job tonight, the plans show 12" ICF below grade, after review and using experience I suggested to the client to have it reviewed, it can be done in 10" and the savings were roughly 15%

Sadly, most engineers that don't deal with concrete or ICF builds, are really shooting in the dark when they engineer those builds. 95% of residential engineers deal with wood frame. When you inject ICF, they go to the extremes, either not enough rebar or they rebar that thing like it is a 30 story hotel.

How much would a typical 2-story home with 3,000 sqft home that is utilizing #4 rebar at 16" O.C. , spend on rebar for such a project? Are we talking $1K - $3K in rebar costs for such a home?

From what I read and understand, rebar is what gives the concrete its strength. I just watched a crew rebar a concrete overpass, wow, I was shocked to see how much rebar there was. It looked like the overpass was made out of steel.
Of course an overpass is not the same as a home but the point is that concrete without properly sized and spaced rebar is VERY WEAK, especially in seismic areas.

Rebar holds concrete together to make it easy, concrete without rebar can come apart, rebar without concrete is useless, put the two together and Wahla, you got some serious strong walls...if designed and built right

As for your bar, without plans I can't give you an estimate, but if your grid pattern is 16x16 or 18x16 depending on your block, take the gross square footage of the wall and multiply by 1.5, divide by 20 then divide by 160 that will give you tonnage of #4, I don't know your local prices.

This is close for estimating purposes, it does not account for special details on lintels, etc. Somewhere you may need #5 for lintels, #3 for stirrups, you may have a lot of openings which can change it, but it's close

Posted By Chris Johnson on 13 Feb 2012 06:41 AM
Rebar holds concrete together to make it easy, concrete without rebar can come apart, rebar without concrete is useless, put the two together and Wahla, you got some serious strong walls...if designed and built right

As for your bar, without plans I can't give you an estimate, but if your grid pattern is 16x16 or 18x16 depending on your block, take the gross square footage of the wall and multiply by 1.5, divide by 20 then divide by 160 that will give you tonnage of #4, I don't know your local prices.

This is close for estimating purposes, it does not account for special details on lintels, etc. Somewhere you may need #5 for lintels, #3 for stirrups, you may have a lot of openings which can change it, but it's close

Just for ballpark estimate sake, on a typical one or 2-story home, 3000 sqft, with a 16x16 pattern, how much would the rebar cost? I can't see it being over $3K but maybe I am wrong.

What is the gross footage of the walls

I paid $2250 delivered for 3 tons of #4, Grade 60. That was enough to do basement and first floor plus attached garage with 9' finished ceilings. Floor plan is about 2500 sq ft plus another 700 ish for garage. We had a little left over that went into the poured driveway.

Posted By galnar on 14 Feb 2012 10:15 AM
I paid $2250 delivered for 3 tons of #4, Grade 60. That was enough to do basement and first floor plus attached garage with 9' finished ceilings. Floor plan is about 2500 sq ft plus another 700 ish for garage. We had a little left over that went into the poured driveway.

What was the spacing on the rebar, 16" OC - both ways? What state do you live in? $2,250 for 3 tons is a great deal.

I called here locally in Phoenix and the quote I got (non-contractor rate) for 2 tons - Grade 60 - #4 rebar - 20 foot lengths, was $2,300 delivered. Of course a contractor would get better pricing than I could. Basically $1K per ton is what I was quoted. So if a home incorporated 3 tons of rebar, one would be looking at $3K for the rebar.

What I don't understand is I read an article on-line how someone claimed they paid $20K more in rebar costs for a 3,000 sqft ICF home than they originally estimated because they changed the spacing from 24" OC to 16" OC. That contractor totally ripped them off, that is what happened. He took a ton of rebar for $1K and up-charged the homeowner another $19K.