I'm nearly at the point in stacking my ICF basement wall where I am up to the level of my attached garage slab and front porch slab.  I believe that it would be a good idea to mechanically tie the adjoining concrete slabs to the ICF wall, but I have seen little to no discussion on this and I don't recall seeing any details on this in any of the ICF manufacturer's online manuals.

Here is what I was planning on doing.  If anyone has any input it would be appreciated.

1)  Cut some 3' lengths of 1/2" rebar; enough to have 1 rebar every 16" where the slab contacts the ICF wall.
2)  Put a 6" 90 deg bend on one end,
3)  Drill a hole in the ICF panel facing the slab at ~ mid level of the slab just large enough to accept the rebar (I'm using self-assemble panel type ICFs, this might not work as easily with pre-made block type ICFs)
4)  Push the rebar through the foam leaving ~2" cover concrete over the back of the hook (~6" embedded in the 8" wall) with ~24" extending beyond the foam to later be embedded in the adjacent concrete slab.
5)  Tie the rebar hooks to the panel ties securely so the rebar doesn't move during the pour.

I'm also at the point of setting anchor bolts to connect my deck ledger board on the back of the house.  This would be fairly straightforward except that I plan to have brick veneer with ~1" air gap installed and can't rely on that for support. 

Here is what I had in mind for those deck ledger board anchors:

1)  Obtain 5/8" x 14" L type anchor bolts
2)  Obtain 2" x 3/16" steel strap
3)  Cut 6-1/2" long sections of the steel strap - long enough to span through the foam (2.5") and the 1" air gap to the face of the brick (4")
4)  Weld the 6-1/2" steel long strap to the anchor bolt edgewise leaving ~2-1/2" bolt to project beyond the brick to attach the ledger board.
5)  Spray a corrosion inhibitor (most likely cold galvanizing spray) on the exposed portions of the anchor assembly.
6)  Bore a 5/8" hole in the ICF panel every 16" and cut a 2" deep slot below the hole to accept the flag anchor.  Holes will be staggered high and low on the 2x10 ledger board.
7)  Insert flag anchor bolt and glue in place in the ICF panel.  Also wire tie inside to hold in place during pour.

Thoughts?  Anything else I should do or do differently?

Thanks.

Hope I imagined it right from your post, if not please clarify!

Porch : We usually embed right sized bars,(4' bars bent in half 90* or not bent but to be when concrete has hardened) this being in porch walls that are extending outwards of the house. If an inset porch you could go the route of the anchor bolt with an 4'' diam. concrete around your bars(bent 90 *).

For the ledger, hope I understood correctly, why not use flange bolts for ledger directly to wall and seperate flange bolts to hold an angle iron above the ledger for brick.
Staggered bolts for ledger are common practice for us and ussually 12 to 16 in. apart depending on span.
Gluing the flange bolts isn't necessary. Drill the the hole, use the keyhole saw down to flange depth. Fit will be tight so no glue required. Once you filled the wall go back to the bolts anstraighten them out.

Hope it helps!

Here is roughly what the front of the house will look like.  The front porch slab extends 7' out from the front wall and is 38' long.  One end of the porch will butt up to the back of the garage (garage doors on left side of image below).  The garage slab and front porch will be built on strip footings built up as required with CMU.  The front porch will be ~2-3' above grade (in the image below, grade slopes gradually downward from left to right, and much more so from front to back - basement is walk-out).  Beneath the slabs will be compacted fill (most likely fine sand or rock crusher dust).  Also for the garage and porch slabs, 8"x8"x16" CMU will be stacked up in vertical columns approximately every 4' on the footing and next to the basement wall.  These will be filled with concrete during the slab pour.  This will provide additional support in the event that the back fill settles any.  The purpose for the rebar tie to the ICF wall is to insure the slab doesn't pull away from the ICF wall for any reason.


I did state that I would glue the flag type anchor bolts to the foam, but that is probably not necessary if the bolt fits tightly.  However, I have found that a coating of Titebond II wood glue really sticks stuff to EPS insulation.  And it is cheap.

Regarding the ledger for the back deck, I did not want any interruption in the brick veneer from the footing to the eves.  My intent was to have the flag anchor bolts protruding out from the wall, then have the brick layers brick around them leaving only the 2-1/2" threaded portion sticking out to attach my ledger board.  I would likely apply some tape over the bolt threads beforehand to keep any mortar from sticking to them.

Posted By arkie6 on 15 Feb 2011 10:27 AM
I believe that it would be a good idea to mechanically tie the adjoining concrete slabs to the ICF wall,

Not necessarily. Depends on your climate. Are you building in a cold climate where the ground freezes in winter, or otherwise?

When I was getting ready to build my house in SW Idaho I talked to a very reputable concrete guy. He said even though most everyone does, don't tie the slab into the house wall. The reason for this is the ground freezes and swells and contracts through the winter season. As a result concrete slabs tend to rise and fall. If they're tied into the wall they are prone to cracking. Slabs that are free to float have a lot fewer cracking problems. My front porch slab, similar to what you are doing but smaller, is free to float around the footing pillars the front columns rest on, and is not tied to the wall.  My back patio and driveway slabs are free to float. Two winters later there are no cracks in any of the three, except in the control cuts. I used no rebar or rewire but I did put fiber in the concrete. My garage slab is also free floating. There are no cracks in it yet, except of course in the crack control cuts.

In a damp climate like the South, the soil under the slab can dry and shrink, then get wet and expand. This can cause the slab to move down and up and cause cracking.

I'm with dmaceld. Even in Texas I would uncouple them on my next house. As dmaceld said, this is true for cold but I would like to add it iis also true for heat. Remember the concept of cold doesn't actually exist there is only absence of heat. Regards.

The idea of letting outside slabs float has been proven over a long time. One issue however is that with homes on full basements there is rarely proper soil compaction for the seven or eight feet of back fill. For this reason we almost always tie to the wall. On ICF buildings we usually use a brickledge just below slab height and insert rebar dowels (straight up) After backfill and slab prep we bend them down into the slab bar and tie. This spans the excavated area. Proper prep of the slab base and proper landscaping around the slab to allow for drainage prevents frost heave.

Good info to ponder.

No real ground freezing concerns here in central Arkansas - footings only need to be 12" deep here. On the front porch there will be a 24" wide x 12" deep footing around the perimeter into hard red clay. Then there will be ~4 courses of 8" block to bring the foundation up to the slab level. Then the interior will be back filled with rock crusher dust. Also, after the porch slab is poured, the brick veneer under the front porch will be supported by the slab. I'm not sure how this would affect my brick if I allowed the porch slab to float and possibly move.

The garage will be 2x4 framed and insulated so I don't see any huge temperature differentials between the house and garage. The front porch is on the north side of the house and will be covered, so it should roughly follow outside ambient temperature.

One more question. Right now I have my front porch slab planned to be ~4" lower than the floor level in the house. This will allow ~1 course of brick under the front door sill. The back decks will be the same level as the front porch. Is this pretty typical for porches and decks? The garage slab will be ~16" lower than the floor level in the house.