Typical ICF vertical reinf. spacing verse ACI-318

[eng003]

I see typical vertical reinforcement spacing in ICF at 48" +/- o.c. depending on the loads. You will arrive at similiar spacings if you follow the prescriptive pca-100 design guide. I am using the AMVIC ICF system software and it is noting my 48" spacing is violation fo ACI 318-08 14.3.5 and I agree it is conflict with this code section?? but Isn't it typical to use this type of spacing?? Even the IBC includes presrciptive tables form PCA-100 using spacing greater than ACI 318-08 allows??

 

[msquared48]

If it has been tested and rated by a certified testing lab, the spacing limitation does not apply anymore.

Mike McCann
MMC Engineering

 

[TXStructural]

PCA-100 was intended to be ACI 318 compliant, but IBC/IRC may have accepted a lesser requirement - or could be using information from an older 318. None of the flat wall ICF manufacturers have done sufficient testing to demonstrate that variation from this is acceptable.

Don't stray too far from 318, since rebar is really not very expensive, and barely meeting minimums provides only the performance assured by those minimums. There is nothing wrong with designing for greater than minimum performance. I am in the process now of designing an ICF house that will have #5 @ 8" (tornado wind design). On 200 ft of exterior wall, the vertical bar for this spacing will be about $900. For #4 @ 48", the bar would be $220. Not a difference which justifies much engineering time, especially if you aren't talking about this big a difference (as with #4 @ 48" v ACI 318 mins)