Can EIFS be used over 1" foam sheathing.  I am interested in it for three reasons: extremely hard, less coats and less expensive vice stucco.  But I am not sure what considerations are needed for application. I am still in the infant building stage and would appreciate any comments as I can still change what I need for the outside where the EIF will be applied. Also any considerations for windows sizes when ordering. I also see that some insurance /window companies (PELLA)don't like it.
THX LRM  

EIFS (Acrylic stucco) must be applied over EPS (bead board).  It cannot be applied over XPS.  In general, installation involves stapling a drainage mat to the Tyvek-covered, wall sheathing, than mechanically fastening 1-1/2" of EPS board.  The base coat, reinforcing mesh and finish coat are then applied.  The drainage mat allows condensate a means to escape and dry out before water damage can occur.  Make sure a quality caulk and backer rod are used around windows and doors.  Proper flashing of windows and doors is very important in case water manages to get past the caulking.  I like EIFS, but advise using only a reputable installer with a proven track record for quality installation.

Here's a photo showing the installation of the drainage mat (blue) and the EPS over Tyvek.

Do you have experience applying EIFs directly to MGO board? I'm thinking of building an MGO board SIPS home and am looking for products that can be applied directly.

That's because some monster lawsuits have arisen as a result of product and installation deficiencies. Whenever complex technology is used to substitute for simpler systems (usually to reduce cost), quality control becomes critical.

For example; caulking is a complex technology often asked to substitute for the high reliability and longevity of simpler mechanical barriers. However, to be as effective it requires much more skill in application. The problem is that while a poorly applied flashing will often leak in the first rainstorm, it may take years (i.e. outside the warranty period) to discover caulking was inadequate.

The quandary for homeowners (and builders) is ensuring enough oversight at the journeyman level. It is easy to inspect flashing, but almost impossible to inspect caulking.