Yeah - I figured as much. I'll be coordinating with structural about the slab thicknesses. I'm most concerned about the wall ties. I don't want them to be obtrusive and rust after they've been broken off.

7 5/8" are common in some markets. My builder friends in Kansas City say that's what they use there. I've only seen even-number increments here in New England.

You can get fiberglass snap ties. Just be careful if the walls are tall; my brother had a 30' monopour fireplace blow out in an almost-finished house once and it wasn't pretty. 

That's my concern WG. The walls are 30'-0" tall.  Not my design. 

Define 'obtrusive'? Easy enough to spec. stainless ties w/ silicone. Or pony up to properly finish the hole.

30' tall? I hope some framed bracing somewhere?

Resident structural engineer here, 1/2" increments are usually doable in my experience, it all comes down to the inherent tolerance of concrete construction & the quality of your local concrete subs. 1/2" is the smallest tolerance that can be hit reliably, 1/4" is very difficult to hit consistently and 1/8" is close to impossible. You might spec 1/8" but you won't get 1/8". Your structural engineer should know the right increment, and they'll want input on that thickness so they can design for strength. Good luck!

Unrelated to the wall question but I have a client at the moment who is adamant about the dimensions of a concrete pour. Since we're evolved beings, we use the metric system but the formwork guys used archaic inchies and feeties. No big deal, numbers are close enough because a hard conversion gives us just under 3.5mm O/A delta. Apparently that's a concern? Dude, your wall is 125' feet long. 1/16" error in either direction is the least of your worries.

Appleseed wrote:

Define 'obtrusive'? Easy enough to spec. stainless ties w/ silicone. Or pony up to properly finish the hole. 

Obtrusive as is easily seen and looks like ::bleh::.  I was planning on using plastic coated stainless steel wall ties.  The issue is the height of the wall makes them rather large.  When they're broken off it's easy to damage the finish.   It's easy for the proper hole finish to not match. I've seen it a lot.

JLC-1 wrote:

 "30' tall? I hope some framed bracing somewhere? "

Oh yeah. There will need to be a lot of that. This project just finished SD and I wasn't involved in it so I'm still coordinating things.

The idea here is to have a board formed wall on both sides for aesthetics that is insulated. Without violating privacy here is the design concept. Again, not my design. 

Like this?  I pass by this one every day.  It was done with tilt-up poured concrete panel sandwiches.

That's what I'm thinking.

I'm looking at multiple options.  

Cast in place insulated board formed concrete panel. 

• A good amount of structural engineering will probably be needed to accomplish this.
• Due to the 30’-0” heights of the panels we will probably need additional steel structure to support the panels. 
• We’ll need to speak with structural about how this works as it will probably be two concrete walls tied together with insulation between.

Precast concrete panels.

• This is literally what precast panels are for.
• I’m unsure about how to finish the outside corner of the boxes or if that is even possible with precast panels.

Tilt up concrete panels

• Cannot finish the ‘back’ side of the panel.
• Would need to use a veneered stone product to mimic board formed concrete on the interior.

Board formed concrete with metal stud wall.

• We would do a board formed concrete wall on the exterior and frame metal stud walls with insulation on the interior.
• A veneered stone products would be used in the interior stud wall to mimic board formed concrete.

Composite siding.

• Use a Resysta type product to produce a board pattern similar to board formed concrete.  

You can finish both sides of tilt-up if you press something into the top after pour. That's how the example in my pic was done. But you're probably looking at a precast panel system if you want better control. I'm balls deep in precast panels and will see my first full wall erected next month. I'm expecting finished corners... fingers crossed.

I was thinking about the stamped look on the 'back' side.

Thanks for the advice. I'm you've raised many of the concerns I have. Glad (and sad) to see I'm not crazy.

proto - any advice on how to define what is acceptable and defective work in this situation?

Use your design mockups to set your parameters. 

One way might be to make a list of the typical repairs on a new concrete wall. Then reverse-engineer the parameters for when an identified repair condition has a threshold. What are you willing to put up with? Then itemize those in numbers and words. Example: Crack size thresholds. Crack length thresholds. Crack position/orientation thresholds. Crack hierarchy of issues to threshold of repair/rejection. Then repair hierarchy of processes. Etc. Do it for finishes, mixes, wood formwork, timeline of form-pulling for ideal embedment of just the right amount of wood fibers...etc

Thanks proto!

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Thanks. Using European products is not going to fly for this public works project. Materials need to be locally available (within 1,000 miles).

Those stainless steel wall ties you've drawn wouldn't fly in high spec build ( thermal bridging )  ... anywho

Oh the wall ties in the 'sketch' aren't finalized. I'm looking at several thermally broken wall tie options.

“you’re welcome’” …..

????????

I still won't be using the product you've been promoting.  It's not available in this part of the US.  

As I said in the OP - it's just a sketch.  The wall ties aren't chosen yet.  I've narrowed it down to three thermally broken wall ties that are available in the US.  Now I just have to see if they will be strong enough to work with concrete walls this high.  

no worries Chad. All good

btw , The two products are global brands and available in the US. We used this system in the projects 10,000 miles away from where it’s been made in Germany.

already regret posting this/ i’m out.

I appreciate the recommendation!

I knew about the product before you mentioned it. It's a European made product and the nearest supplier to the project is more than 1,000 miles away, hence why we cannot use it. I'm going to be recommending to the owner that they revise their material limitations but I have to be realistic. :(

Thanks for the advice.  I really appreciate it!

Coping details?  I assume you mean the parapet cap?  Don't worry about that - it' won't be done that way.  There will be a standing seam metal roof over the concrete walls.  That was just shown there so other team members wouldn't freak out about the top of the wall being 'open'. 

After so many years, I finally got to see the Salk Inst recently and, with a board formed experience from work under my belt, the visit was an absolute wonder..! Going to Japan might blow my mind!

yes the parapet cap is what i meant. I thought it was coping in English? Good to know.

The Salk is beautiful. I saw it a few years ago when it was being renovated, but even in that less than ideal state it was clearly a masterpiece. Ando concrete is technically a lot cleaner and sharper, but I like the Salk. It feels warm somehow. Something I have never felt with Ando's work.

But if you are into concrete definitely visit Japan. There is a lot of amazing works worth seeing. Including this one most recently (https://www.spoon-tamago.com/keisuke-oka-arimaston-building/). It's a crazy hand made building filled with invention, a bit like Gaudi. If you think board-formed concrete is pushing the limits, this guy is so far beyond the avant-garde he feels retro.

[coping def works]

It's all good Will! Thanks for all the insight!  

That's certainty the 'look' we're going after. Writing the spec and creating the details to get that 'look' seems to be rather complicated and expensive. Around $70 per SF of board formed concrete. :s

Was going to suggest this as well. Precast can be done with boards, or board forms, depending on what you're going for. The nice thing is, less expensive and better quality control BUT it takes a ton more coordination.

I was also going to suggest precast. The co-ordination isn't much more. Once the foundation and structure are in place you will need an accurate survey before precast fab happens. And of course a crane so it may add to the $$ but likely shorten the timeframe. Hard to say without knowing the scope.

I'm in agreement. I told the team this is literally what precast panels are for. It's all going to come down to cost. We have about 9,800 sf of 'concrete' wall. I figure it will cost at least $70/ SF to do BF conc so around $700k. We're doing an SD estimate now so . . .

FWIW finished a precast building last year, about 2.5x your sq. ft. Panels were comprised of 3"conc, 3"rigid, 5"conc. outside to inside. The panels were the biggest we could manage with getting into crazy trucking. Nominally 12'W x 40'H. foundation bearing and clipped to the structural concrete slab at top. This was a deflection / lateral support anchor. Project was in the NE and all the energy modeling worked out. Mostly simple panels w/ window penetrations, score lines, and alternating etched surfaces. I don't recall the pricing but I think your number is low for the NE. Hope this is some help.

Thanks! 

I'm really not sure about the cost of BF concrete. I do know it adds around $40 a sf to a standard cast in place wall. I'm thinking that local subs will see a BF job and charge in the $80-$90 / SF range.

I'll give an update when we find out the SD pricing.  

How effective is the insulation to prevent condensation inside? Are the the walls still really cold to touch?

Thanks gibbost!

JLC I've done plenty of precast sandwich panel projects, and in my experience the interior concrete stays the same temperature year round - it's effectively a huge thermal mass that helps a little to mitigate especially warm or cold days

Thanks gibbost and bowling_ball. We're thinking of doing a 10" interior concrete (structural) 3" rigid insul, and a 5" finish panel.

I know 3" rigid insul doesn't seem like much however we're in climate zone 5b so it's nearly double what is needed.