Reading through some ICF manuals they suggest mounting a strip of wood 4" in height at the top of the wall to nail in crown moulding. Does this need to be recessed into the foam so that it is covered by drywall? If not it would seem to violate the fire rating of the drywall covered wall.

Leslie,
When the foam is stacked to full height and before the concrete is poured, take a laser and mark the top of the walls 2" below the cut off line. Buy some more of the 2 1/2" steel track that you mounted the first course in and put it upside down on the top of the wall. Set it pour height and screw it into the plastic webs. This give you a smooth straight screed line for the concrete and then becomes a nailer strip across the top of the wall.
Hope this helps.
Joe

"it would seem to violate the fire rating of the drywall covered wall."

I don't understand the coorelation you indicate in this comment?? However, Joe's way works too. But many times a client changes on the fly what they want to do with interior trims and design elements. Using a 4" high piece of wood, or any size related to the size of the crown you want to use, works fine by glueing and nailing/screwing this backer in place.

I added a combination layered crown detail in a bedroom at my home last year this way; I built the house in 96 :-)

James,

Let me clarify. I was under the impression that the entire wall, floor to ceiling, needed to be covered in drywall to achieve the 1hr fire rating. If 4" of plywood is substituted for drywall at the top of the wall for the purpose of attaching crown molding , would this not violate the fire rating?

That was my confusion. It would seem the plywood would need to be recessed into the foam and covered with plywood or an alternative attachment like the metal channel used.

Do not confuse 1 hr, 2 hr., etc fire ratings and "Flame Spread and Density" and "Garage Separation from Habitable Spaces"in residential construction.

It is not a 1 hr barrier, but according to the IRC2003 which we use here in CT....

"R314.1.2 Thermal barrier. Foam plastic, exceptwhere other-
wise noted, shall be separated from the interior of a building by
minimum 1/2-inch (12.7 mm) gypsum board or an approved
finish material equivalent to a thermal barrier to limit the aver-
age temperature rise of the unexposed surface to no more than
250F (121C) after 15minutes of fire expo-sure to theASTM
E 119 standard time temperature curve. The gypsum board
shall be installed using amechanical fastening system in accor-...and so on......

The concrete walls of an ICF are rated for almost any required rating, however, there are times when the 2.5" of EPS foam at the wall/ceiling intersection may, I said may, come into play. What happens there is a vertical compromise when a rating is required which needs to be determined during the design phase, not while building!

James has provided the full explanation ... I call it the 15 Minute Thermal Barrier for short.

SO for an ICF wall supporting a suspended slab no drywall is required? Unless the wall in question is seperating garage or other residence. I was under the impression that all walls needed to be covered to protect foam?

SO for an ICF wall supporting a suspended slab no drywall is required? Unless the wall in question is seperating garage or other residence

?? No one said that, and the code does not say that. I said basically, do not misinterpret which walls require which finishes to comply with code. I suggest you have your design professional handle these details and note them for the permit plans!

If I understand the original Q, it was to attach crown molding. Same as base board application. Run the 1/2" ply strip at any location on the suface of the ICF. Butt your 1/2" drywall to the strip, bed and tape the joint. That gives you the nailer you need and seals the joint with compound. That is acceptable to building departments we have worked with in our area of FL. check with local code for acceptability. GR

Flaicf,

Thanks for answering my question. I'll stop asking stupid questions on this forum. Maybe the architect can come on this forum and ask stupid questions on his own.