Logix added a section to their wall engineering documentation, calling for additional connection between footings and walls, and between wall tops and floor frame, for jobs done in seismic zones. For me, designing for buildings in seismic D1, that now means the vertical dowels that connect footings to walls are called out at 18-inch spacing. It also means that each floor joist or floor truss that bears atop walls be clipped with one Simpson A3 18-gage angle clip, four (4) 10d x 1-1/2 nails in the sill, and four (4) in the joist or truss. If you are designing or building with ICF in seismic zones, what is going on with you? Logix does not call for more wall rebar. With earthquakes, it is all about connections, and thus while the wall rebar remains the same, the connections get reinforced.

Welcome to my world...everyday

So, what details apply for you in your zone?

High siesmic zones require expensive and extensive detailing this is achieved through so much additional hardware it will drive you nuts...I know, it added days to my first project when I moved to California.

1/2" AB's are non-existant, everything starts at 5/8" and goes up, spacing never exceeds 24" and in a sheer situation can be as tight as 6" o.c. (Real fun trying to get concrete in there) You can not wet set anything, everything has to be in place prior to pour. All concrete requires special inspections, basically pour day is expensive, you need City/County approval, Engineer of Record Approval and Special Inspector Approval of you rebar, then Special Inspection for placement and test samples (Min. 4 sets every 5 trucks).

Every truss needs to be clipped (L50, L70, Etc) to a top plate and usually a hurricane clip as well, the blocks on top of the plate between the trusses need to be clipped (L50 x 2 pc) on every block. Panel edges normally require solid blocking.

See your other thread about hanging floors, than add blocking again to the panel edges and in some cases a CS16 strap continuous and nails in every hole.

So the next time someone says California is overpriced on housing, guess where the money goes!!!

When you want to start a thread on Rebar I can show you some scarry stuff. Paul Stevens came down here about a year ago...I think he was happy to go home after three weeks...

Chris

I surely can relate! During the construction of our 10ft high wall for the City of Burbank (power and water) in 2003; the required Rebar left very little room for the concrete. To further complicate matters, spec's required 105 lbs/cuft - 3000psi concrete ( the wall was built over a access tunnel). The concrete weight/strength was achieved by using a cellualar concrete mix (quite hot - 8+ bag mix), which was very helpful in the flow.

That being said; at least the great state of CA. is very progressive concerning alternative (ICF) construction and re-newable energy saving technologies. At least (hopefully) comments like "Why don't you build with wood as everyone else"; are unheard of in your neck of the woods :)!

Flyash or Slag is your friend, it makes flowability very helpful in these situations, but concrete is still vulnerable to get hung up...hence the vibrator and it's function.

I haven't had to use 8 sac mix before, most is 6 - 6.5, with the flyash I get cylinder breaks of 5000+ after 56 days

Visiting Chris and seeing first hand what he has to go through was quite an experience. You sure understand why the install price is higher than usual. But you just can't beat the weather (at least the time I was there!). But as tough and time consuming as it was, I would go back in a second!! Hint, hint.
Paul Stevens

Fly ash in a ICF block can also be your enemy.  It depends on the grade. There is no standard for or spec in the USA and you don't know what your getting when you allow fly ash in an ICF mix. 

What is the enemy part of this? This is new to me.

Almost all spec's I get call for a minimum of 15% fly ash, if LEED points are required it goes up to 30%

Paul, Daisy says come on back down!!!

The quality of the fly ash varies with the coal consumed.  Up to 65% of fly ash available in North America should not be used in concrete to replace cement unless the fly ash has been processed to make it suitable.  Using the wrong type of fly ash can result in lower test results.  Usually, the ready-mix companies that I have used will have an admixture that contains the right type of fly ash and the percentage will not exceed 20%.  Some tests have been conducted on structural concrete that contained up to 60% fly ash.  Again, it really depends upon the type of fly ash, the mix and the end use.

Flowable concrete (used for compaction and soil stabilization but not for walls) can use up to 95% fly ash. 

Bottom ash is another completely different animal.  Just because it might be available does not mean it would be the right thing to use for structural walls.  I have not seen enough testing to convince me to use bottom ash. 

I can appreciate what you have described, I am confident that the fly ash being used at my local concrete supply is acceptable, considering the liability they would incur should a problem arise. The reason I say this is fly ash is heavily promoted now for LEED points, engineers are required to examine all mix designs prior to ordering and placement, the mix design identifies the source/location of the raw materials. Everything that is needed for LEED. The funny part to the LEED thing is they want fly ash...There is no coal within 500 miles of me, so how does this attribute to points is beyond me.

So, I feel safe now, but thanks for the heads up, I will mention it to the salesman and see his reaction/comment.

Chris, tell Daisy to make room for 4, this time Mischele and the kids are coming too, looks like another trip to Alcatraz!!

Gene,

I build in the Pacific Northwest, the same seismic zone as CA, the most restrictive D. I have been building with Logix since it first came out and we rarely use Logix engineering. Usually when we do it is for a simple little building in one of the podunk counties where they don't pay a lot of attention to the engineering.

The engineering in the Logix prescriptive path is mostly derived from the IRC, that is why they make reference to the seismic zones D1 and D2. The issue that I have with the IRC is that it is so conservative and restrictive that you get ridiculous amounts of unneeded rebar in your walls. You also get ridiculous and stringent attachments and details for all of your connections. So my opinion is to get a great engineer that actually does the calculations and only references the IBC seismic zone D. The engineering in the IRC is someone else's calcs that anyone can use, you don't have to be an engineer to use the IRC.

I frequently do basements with 6" walls and #4 grade 60 rebar on a 16"X16" grid, and the verts from the footing are on 16" centers just for convenience, I believe we can stretch those out to 18" in the basement. Above grade is another story we can stretch the verts out to 24" or more in many cases. Our above grade steel is also 16"X16" #4 because the ACI has a specific steel to concrete ratio that has to be satisfied, and I believe that a 16X16 grid of #4 in 6" is the best we can do with the 8" modules. Heck we are currently finishing up on a 4 story, 16 unit ICF condo project that is 4 stories of 6 inch on a 16"X16" grid.

My experience has shown me that a great engineer can be invaluable and save the project tons of time, money, headaches, and heartaches. We also use some tricks to get around having to get special inspections. We have a proven ICF mix design that we have used for years. We have tons of test data on it and it uses flyash and slag. Anymore we use about 50% flyash slag mix with 50% cement and we get 28 day breaks at 6K to 7K. So I have been having my engineers add into their general notes that a special inspection is not needed if the following mix design is followed. So far I have not had a problem and everyone seems to like it, plus it is saving $500,$600,$700 every time we pour.

ICF Contractor

PS Who is going to PCBC?