Hi All,

Realized we missed a connection detail that could hamper our thermal efficiency, so figured I'd ask you fine folks if you know of an elegant (or at least workable) solution.

The house isn't built yet (just at the finalizing drawing stage).
It's a 2-story insulated concrete form, with an exterior balcony.

I received the plans back from the drafter, and it has the detail shown. Seems to be like it's going to create thermal bridging, especially in our down to -40C winters.

Any suggestions on how to improve this detail? Due to the design of the house, removing the balcony entirely would look severely odd. I'm not certain we could independently support it either.

Thanks in advance for any help you can offer!

Posted By Geergirl on 05 Jul 2015 12:36 AM
Hi All,

Realized we missed a connection detail that could hamper our thermal efficiency, so figured I'd ask you fine folks if you know of an elegant (or at least workable) solution.

A possible solution is with what the Germans developed for thermally breaking concrete balconies. It's called the Schock Isokorb

Another way to support the balcony is with columns up next to the house provided there are no windows or doors that the columns block below.

I can't believe I'm agreeing with Lbear, but check out Schock Isokorb. It is a structural element that will allow you to thermally break a concrete slab. Used widely in mid-rise multi-family construction.It's not cheap. but it is elegant and it works.

Well you could use longer Jbolts and only open up the ICF in a square around the jbolts, and place the ledgers out on the face of the ICF. This would greatly reduce the thermal contact between ledger and concrete to the area around the jbolts. Or instead of using jbolts and a ledger in contact with the concrete, spec out something like a Simpson ICFVL That pushes tabs thru the ICF. These are poured in place and hang the ledger outside the ICF thermally broken from the concrete except for the anchor tabs passing thru the ICF into the concrete(necessary evil with any connection)... There are some other joist/truss hangars that install in this fashion without removing the foam, but the name escapes me right now. The simpson stuff is common(perhaps a little spendy) but the engineers like it because it has documented specs they can more easilly design for/signoff on...

What ronmar said - look into putting the ledger over the foam, not removing the foam. I expect that glued and pulled tight with the bolts, it would work (roughly, a 12' 2x12 against 15 psi foam should hold 26,000 pounds). You can put a little spray foam over the bolt heads.

Ronmar, I think you're going to be the winner - my husband just found and showed me the simpson strongtie ledger attachment as well!
Seems simpler than the isokorb (not a huge fan of new european stuff, though I did send them an inquiry last night).

geegirl - this is what you need http://www.strongtie.com/products/connectors/icfvl.asp
if you use them on the exterior you will need galvanized self-tappers you can use the standard self-tappers on the inside.

geegirl - this is what you need http://www.strongtie.com/products/connectors/icfvl.asp
if you use them on the exterior you will need galvanized self-tappers you can use the standard self-tappers on the inside.

geegirl - this is what you need http://www.strongtie.com/products/connectors/icfvl.asp
if you use them on the exterior you will need galvanized self-tappers you can use the standard self-tappers on the inside.

I did mine the way ronmar said- I cut holes in the foam to let the concrete come flush with the surface of the ICF. I did the same thing to hang the ledgers inside. My contractor adviser said that you had to pull the ledger up against concrete, not just foam. The Simpson product sounds about ideal, though.

Another option is the Windlock 6" diameter anchor tunnel with 1/2" anchor bolts to secure the ledger. This provides solid concrete backing for the ledger while reducing thermal bridging compared to complete removal of the exterior ICF foam.

http://www.buildsite.com/pdf/windlo...382135.pdf

This link shows an anchor bolt with a flag welded to the bolt to transfer the load from the ledger board to the concrete.  Simple to install, but these have to be custom made.  This is what I built and used to attach my exterior deck ledger to my ICF wall.  I also extended the 3/16" x 3" flag an additional 4" past the exterior foam to span across my brick veneer.

http://greenbuildingtalk.com/Forums...fault.aspx