Megan,
 
A good article on icehouses is:
 
   Helen Tangires, "Icehouses in America:  The History of a
     Vernacular Building Type," NEW JERSEY FOLKLIFE 16 (1991)
     33-43.
 
There are a lot of interesting illustrations of the ice
business in:
 
   Joseph C. Jones, Jr., AMERICA'S ICEMEN:  AN ILLUSTRATIVE
     HISTORY OF THE UNITED STATES NATURAL ICE INDUSTRY,
     1665-1925 (Humble, TX:  JOBECO Books, 1984).  [Send
     inquiries to JOBECO Books, Box 3323, Humble TX 77347]
 
Icehouses have been around for centuries but apparently became
popular in the U.S. in the 1830s and '40s, in part due to
advances in ice-harvesting technology.  There also seems to
have been a shift in American eating habits and tastes (pardon
the pun) with an increased interest in refrigerated foods--so
you may want to look at historical food-ways in your region as
well.
 
Regarding dairies--there is a thesis here at the University of
Virginia (in the architectural history program) which may be of
use:
 
  Sallie Arlyn Smith, "Chesapeake Dairies:  A Prototypical
    Outbuilding Study of Southampton County, Virginia," Thesis,
    University of Virginia, Charlottesville, 1982.
 
This should be available through interlibrary loan.
 
Good luck,
 
Marty Perdue
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