Help!  I have a customer that is using ICF blocks to build the stem walls for modular homes.  The walls are 4 ft. high and about 3 ft. is left expposed on the outside.  Here is the problem; they are using the crawl space as a plenum for the hvac system.  The local Building Departmant requires that the stem wall be water proofed in this instance.  The builder wants to incorpporate the waterproofing with a covering of the exposed ICF.  Has anyone had a similar problem?  What  was the solution?

Why use the`whole crawl space for the plenum? Non habitable space tents to be dirty, dusty and smelly. I would imagine this would shorten the life span of the furnace and contribute unwanted odours throughout the living areas.

Anyways to answer your question, use acrylic base coat for EIFS installations on the above grade exposed areas

Maybe the same reason I did. I get a warm floor in winter time, not the usual radiant heat temperature level but warmer than the room air above. With air moving through the crawl it won't be dank and damp so no odors.

Larry,

One caution the customer needs to aware of. Since the ICF blocks will be enclosing a conditioned space integral with the living space the inside surface of the blocks has to covered with a thermal barrier such as drywall. Also, since in winter the air in the crawl space will be substantially warmer than the ground surface he should insulate the ground. To make it really work good he should pour a thin slab throughout the crawl. Also, since he's dropping a factory built house onto the foundation he will have to make sure he gets an absolutely air tight seal between the stem wall and house frame.

From my own experience thus far while building my house, using the crawl space for a plenum is not at all a crazy idea.