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RE: ICF Basement Wall with Top Restraint

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A floor system restraining the top of the walls has been done for many years with concrete and CMU.  It just needs proper connections and nailing.  I’ve done it a lot, but not for seismic loads.  I’ve also restrained walls by tying them into slabs, but there are several things you have to take into account, such as settlement of the soil under the slab.  You can detail the ICFs such that you can get the values you need with some manipulation of the forms.  It’s easiest with flat wall forms, but can be done with Polysteel waffle wall, too.  Some jurisdictions require a thermal break between interior and exterior concrete.  By tying exterior concrete into the ICF concrete, you’ve defeated some of its purpose.

 

If you must use the Simpson hangers, they will take a certain amount of combined lateral & vertical load, but good luck getting those values from Simpson.  The best way to deal with that is to cut out the foam at the hanger and either recess it, or allow the concrete to come out to the hanger (Back when I was with the ICFA, I offered my assistance to Simpson for developing an easy-to-install hanger wit properties for design, but they declined).    

 

I prefer the old-fashioned way of anchor bolts and ledger.  Watch the eccentricity.

 

Jerry D. Coombs, P.E.
President,

Coombs Engineering Services
214-287-4696

www.coombsengineering.com

jcoombs(--nospam--at)coombsengineering.com

 

From: Joseph R. Grill [mailto:vveng(--nospam--at)cableone.net]
Sent: Monday, January 25, 2010 1:57 PM
To: seaint(--nospam--at)seaint.org
Subject: ICF Basement Wall with Top Restraint

 

I have a client that wants to use ICF Flat Wall panels in a basement wall situation.  Actually, it is a lower level garage wall in a (sort of daylight) basement in a residence.  He also wants to use Simpson Ledger hangers (ICFVL) for hanging the floor joists to the ICF walls.  With the top of the wall restrained I can get enough reinforcing in the concrete for the flexural loads.  But, these particular hangers are installed on the outside of the insulating face of the ICF wall therefore the insulating “foam” face will be under compression.  Can the floor framing, (wood joists and plywood floor system) still be considered to restrain the wall. 

 

Also, on the soil side of the wall there is a concrete slab which if anchored to the top of the wall (the wall is 10’ high) can restrain the top of the ICF wall.  I was going to have the client pour the slab over the top of the wall with a thickened section at the slab then continue with the upper floor ICF walls above the slab.  But since the concrete thickness at the wall is only 6” I am not getting much for restraint values with a #4 dowel extending into the slab and hooking into the wall.  I don’t think there is enough of a concrete thickness at the wall to develop a hooked bar.  Alternatively, could I use anchor bolt values from table 1911.2 from the IBC using #4 bent bar in 2500 psi concrete, if acceptable, would give me a shear value of 1250 lbs at each dowel.

 

I would rather have a note for shoring the wall temporarily and tying the wall into the slab.

 

I had looked at all this some time back, but my client has made some changes which have increased the restraining value at the top of the wall.  At the time I was much more comfortable with what I had.  I had set up the whole situation on a 3D model (I had a lot of time back then) to see what the top restraint values would be.

 

I hope all this makes some sense, but thanks for your time.

 

Joe Grill