Do you need to sheetrock the Insul-Deck foam when you do a dropped ceiling?  Am looking at HVAC and plumbing under the deck.  Also, do you need to have sheetrock between a framed out wet wall and the ICF?  Last question.  When stairs run along a ICF wall do you need to have sheetrock between the stringer and ICF?  Thanks  David

It depends on the drop ceiling. The rule is that the foam must have a thermal barrier to prevent it from smoking when exposed to the heat of a fire. If a fire can start in the drop space then yes. Normally if you frame out an ICF wall (but why would your?) and the frame is right against the foam, you would not need additional thermal protection. Same goes for the stair stringer although things are normally neater if you put the drywall on first and then hang the stairs or leave a 3/4" gap to drop the sheet through later.

Thank You.  The wet wall is for washer and dryer going on outside wall.  Between the valve box for the washer and the dryer vent box the depth is more than 2.625 inches.  So it would be easier to frame out.