So I worked with an engineer on my house plans.  I have a two story house (6" ICF) sitting on a basement (8" ICF). 

The engineer specified #5 rebar for vertical reinforcement every 1' oc and #5 horizontal every 18" oc.

Has anyone else run across spacing this close?

John

That is consistent with the reinforcement used in my ICF basement due to soil type and height. I didn't use ICFs for above ground so I can't help you there.

Greg

Yes, engineers are mostly bound by ACI 318 and generally don't stray from there required 18" o.c. spacing. Many who
have ICF experience will vary from this method, but those with less to none will follow ACI. This spacing could be justified in
the worst case soil conditions, but would definitely be overkill for above grade construction.

Dave

It seemed like overkill to me on the second floor.

I agree about the soil comment, however I'm not a mind reader and don't know where you are building. You may be able to review the IRC code and discuss it with the engineer, who may have a reason for the amount of rebar specified!

Bonzai,

Consider yourself lucky, here in Southern Oregon we fall into a seismic zone 3, and we don't get many jobs where we can have our steel that far apart. on our 12" walls, we actually have two seperate continuous horizontal rebar at each course (18" o.c.) and on one of our current jobs vertical #8 dowels at 8" o.c. spliced with #6 verticals in the walls at the same spacing, and #5 verticals at 16"o.c. spliced with the same in the walls. We've dealt with worse but would still love to get a steel schedule that easy anyday.

Jesse
ICF PRO
Southern Oregon

Jesse,

The double layer of rebar is not so much a product of the siesmic zone you are in but a product of the minimun steel to concrete ratio specified in ACI 318.

ICF Contractor

I'm building in Lincoln NE, and there isn't much for seismic activity here, but there is wind. So far the response I got back from the engineer is...

"The basement walls are retaining and other floors are not. However due to the step in wall size (8” to 6”), the smaller wall size gives us a shorter distance to the tensile reinforcement. The smaller the distance “d” is from the face of the wall to the tensile reinforcement, the higher the load is in the reinforcement. "

I don't know what loads they are running these against. I did run across a footnote saying that all designs were a minimum of 1/3 stronger than their Maximum testing, so that might be part of it.