I grew up setting and pouring foundations.  I run a foundation business with my family currently.  We do not use icf's, but I am planning an addition onto my house and would like to utilize the materials that i already have and add the insulation after.  Are there any downsides to this approach,  other than extra labor to add the insulation after?  I just really know the forms I am using in and out, not that i have a problem with ICF's

Will there be VOC's from the glue used to attach the insulation?

And furring strips or some kind of attachment method for both the interior and exterior wall coverings.

That's about all I can think of.

randynh,

Board insulation can be added to some conventional forms before the concrete is placed.  If the form ties will accept board insulation, then place the insulation in the forms on the exterior side only.  This method will reduce the amount of labor.  The thickness of the board insulation (R-value) should be determined by your location.

If the insulation can not be placed inside the form and mechanical fasteners will be used, then try to install the insulation board right after the forms have been removed.  Waiting until the concrete cures will require more labor when using some types of mechanical fasteners.

See http://www.preciseforms.com/easi_wall_system.htm for another approach.

I have seen the ties that hold the insulation in place. Looks as though this method could be a pita. Do you know if they make a form tie that would hold the insulation in place after the wall has been stripped?

No, I have not seen a form tie that would hold the insulation board in place after the wall has been stripped.

If you plan to install brick on the exterior, then closed cell spray foam can be applied by some companies smooth and consistent enough to replace the need for board insulation.  Brick ties need to be installed prior to the spray foam.  The brick ties are used by the spray foam installer as depth guides.  The secret to installing spray foam for brick application is to apply the foam in thin layers.

Is there a reason you can't stab the insulation boards onto the snap ties?

I would still have to glue or secure the insulation with a fastener.

Only behind the above ground grade portion, dirt does a good job holding it in place without penetrations below grade.

the inside also

Concrete bonds to EPS. Strongly. I inserted 4" thick EPS panels on the inside of my outside concrete forms before pouring concrete and poked the ties through the EPS. After the concrete cures, it is impossible to remove the EPS without completely destroying the foam panel. It bonds so strong that you'll have to scrape it off the concrete and you still won't be able to get all EPS residue off. If you insert the panels before pouring concrete you won't need any glue and you won't need mechanical fasteners to keep the foam attached to the concrete.

you are correct the foam does stick to the concrete. I use it occasionaly to create a brick shelf and I have to cover it in grease or poly if I want to be able to reuse the pieces. I am just going to install it after. I don't think that it would be too big of a deal

Foam in the middle of the concrete makes sense from the standpoint of not having to finish the inside or outside, especially with form liners. And from a thermal mass standpoint. Does it require engineering to meet codes? Ie, not clear to me that 4" concrete + 4" foam + 4" concrete is the equivalent of 8" concrete.

Such a design might be a good area to get into as a possibly better/cheaper ICF alternative.

http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0061/0901b80380061a97.pdf?filepath=styrofoam/pdfs/noreg/179-04047.pdf&fromPage=GetDoc

I see a lot of problems with that set up. How do you pour and not have the insulation go to the form? The pressure will move it all over the place. unless it is precast I guess. There technically isn't enough room for rebar. Generally you need 2" of clearance from the face of conrete. This is not structurally as strong as an 8" wall

Maybe a dual/split hose (one on each side of the foam) would keep it centered during the pour. Along with some rebar and perhaps special centering ties. With above grade walls, isn't the reinforcing requirement quite low - perhaps use steel mesh. This would then be a poured instead of sprayed SCIP (which is known to work structurally, even with 2" of concrete on each side). Might have to use self-consolidating concrete.

maybe. or have precast panels made

Two good examples of foam between two wythes of concrete:
ThermoMASS
EASI-Wall Inserts

With ThermoMASS only the inner wythe of concrete is structural.  With EASI-Wall Inserts both wythes are structural since it is a true composite wall.

Yes, engineering is available for both types of walls.