"McMansions", also known as "garage mahals", "starter castles", and "Hummer houses" are all synonymous for the latest phenomenon in home building that has communities across the country banging down the doors of local City Councils to enjoin builders from destroying the character of their neighborhoods. The debate concerns interests of property owners who want to be able to use their own land as they see fit versus the interests of community members who want to maintain a uniform neighborhood appearance and not have a huge eyesore on their block, literally casting a shadow onto their humble, and often historic, homes. There is a wide range of issues at play in these communities, including constitutional rights, zoning issues, and even energy and water concerns. Though McMansions are causing a stir throughout the U.S., the solution is left to the 40,000 local governments across the country who will ultimately determine whether to eliminate Super-Size from the menu of housing permits, or to allow the expansion to continue. 
McMansion has been defined in various ways: (1) "a large home by world standards and located in a low-density sprawling subdivision"  ; (2) "not just a place to live, but an assertion of the American sense of identity and a statement of propensity" ; and (3) "a large modern house that is considered ostentatious and lacking in architectural integrity."  Behind all these definitions is the theory that some people think bigger is better, but not everyone agrees.
There are 2 types of McMansions: mass built houses in suburban areas, and houses built in existing neighborhoods of smaller houses, where an old, small house is torn down from the lot and a new McMansion is built in its place.  The focus of this article is on the second type, since this type has been more controversial. McMansions built in older neighborhoods are generally too big for the lots, too big for the surrounding neighborhood, and even too big for the number of people who actually live there.  While the average square footage of houses is steadily increasing, the average household size has dropped from 3.35 people in 1960 to 2.58 people in 2002.  While the average size of homes in 2004 was about 2400 square feet, new homes of 10,000 square feet or more make up 1 percent of the total number of new homes built each year, which amounts to approximately 10,000 new homes per year in recent years that are 10,000 square feet or larger. 
So, what's all the fuss about?
People are buying existing homes in neighborhoods, knocking them down, and building on the entire lot, leaving no green space. Neighbors feel this creates an architectural eyesore that not only looks terrible but also instantly drives up property taxes which sometimes forces people out of neighborhoods where they have lived their entire lives, eliminating mixed-income neighborhoods and changing the class structure.  The other main point of tension is that most of these torn-down homes are historic and once they are gone, the character of the neighborhood is destroyed and can never be restored. Historic neighborhoods are especially vulnerable to destruction because they generally occupy prime spaces near city centers, and are located in neighborhoods with character, which encourages people to buy up property and build their huge homes in a convenient location to shorten their commutes. 
Proponents of McMansions argue that people have a right to use their property as they see fit, and there is even an argument that the First Amendment should protect people's rights to free expression in the form of residential architecture.  They also argue that McMansions are good because they are new construction in older neighborhoods, which brighten up the neighborhoods and bring a lot of tax money to small towns.  And, if these arguments are not convincing enough, there is the always-compelling argument that "even a mega-house is better than a crack house." 
Opponents include neighbors in the community and City Councils across the country who are charged with making zoning ordinances, which determine how neighborhoods will look by regulating things such as how far a house has to be set back from the street, what percentage of a lot can be used to build a house, and how high houses can be built.  Cities across the country are experimenting with various ordinances to control the spread of McMansions and preserve the character of their cities.
For example, in Austin, Texas, a builder who is knocking down an old house to build a new one is constrained by certain size limitations meant to keep neighborhoods looking more uniform. An increase in size from the old house can only be up to whatever is greatest of: a 2500 square foot increase in size, a 20% larger house than what was removed, or a 0.4 to 1 floor-to-area ratio for the lot. 
In DeKalb County, Georgia, residents of a neighborhood can successfully quash the proposed building of a McMansion by obtaining the signatures of 60% of the neighborhood's residents and seeking an injunction from the county's board of commission for a zoning overlay. 
Arlington County, Virginia, has adopted an ordinance allowing for houses to be built only on 30% of any given lot, which allows for more green spaces and less overwhelming houses in neighborhoods. 
Other areas of the country allow the mega-homes to be built, but impose fees and energy efficiency requirements that must be met in order to meet the energy concerns of those areas. For example, homes in Pitkin County, Colorado, that are more than 5000 square feet must provide onsite renewable energy (i.e. solar panels) or pay a $5000 energy fee, which increases as the size of the house increases.  Also, in Marin County, California, homes over 7500 square feet are required to provide at least 25% of their energy from solar panels without exception. 
Because this is a local issue unique to each community, each City Council will continue to experiment with ways to regulate McMansions through city ordinances. Eventually, though, someone will get upset over his inability to build a McMansion of his own, and one can count on some contentious litigation in the near future.
 Christopher Soloman, The Swelling McMansion Backlash, MSN Real Estate,http://realestate.msn.com/buying/Articlenewhome.aspx?cp-documentid=418653
 Edward H. Ziegler, Urban Sprawl, Growth Management and Sustainable Development in the United States: Thoughts on the Sentimental Quest For a New Middle Landscape, 11 Va. J. Soc. Pol'y & L. 26, 42 (2003).
 Jennifer Evans-Cowley, McMansions: Supersized Houses, Supersized Regulations, Tierra Grande, Jan. 2005, http://recenter.tamu.edu/TGrande/vol12-1/1713.html
 Orin Hargraves, New Words, 8 Green Bag 2d 125, 128-9 (2005).
 Evans-Cowley, supra note 3.
 Cathleen McGuigan, The McMansion Next Door, Newsweek, Oct. 27, 2003, available athttp://www.msnbc.msn.com/id/3225775/
 Joan Lowy, Communities Rising Up Against McMansions, Scripps Howard News Service, Feb. 7, 2005,http://www.hgtv.com/hgtv/rm_home_building_other/article/0,1797,HGTV_3727_3529761,00.html
 Communities March Against McMansions, CNN, March 27, 2006,http://www.cnn.com/2006/US/03/27/mcmansions.ap/index.html
 Id.; see also Soloman, supra note 1.
 See generally, Janet Elizabeth Haw, Architecture as Art? Not in My Neocolonial Neighborhood: A Case for Providing First Amendment Protection to Expressive Residential Architecture, 2005 BYU L. Rev. 1625 (2005).
 Soloman, supra note 1.
 Evans-Cowley, supra note 3.
 Soloman, supra note 1.
 Communities March Against McMansions, supra note 9.