The tiny house movement (also known as the "small house movement") is a description for the architectural and social movement that advocates living simply in small homes. There is currently no set definition as to what constitutes as a tiny house; however, a residential structure under 500 square feet (46 m2) is generally accepted to be a tiny home.
In the United States, the average size of new single family homes grew from 1,780 square feet (165 m2) in 1978 to 2,479 square feet (230.3 m2) in 2007, and to 2,662 square feet (247.3 m2) in 2013, despite a decrease in the size of the average family. Reasons for this include increased material wealth and prestige.
The small house movement is a return to houses of less than 1,000 square feet (93 m2). Frequently, the distinction is made between small (between 400 square feet (37 m2) and 1,000 square feet (93 m2)), and tiny houses (less than 400 square feet (37 m2)), with some as small as 80 square feet (7.4 m2).Sarah Susanka has been credited with starting the recent countermovement toward smaller houses when she published The Not So Big House (1997). Earlier pioneers include Lloyd Kahn, author of Shelter (1973) and Lester Walker, author of Tiny Houses (1987). Henry David Thoreau and the publication of his book Walden is also quoted as early inspiration.
A Wisconsin producer, Escape Homes was founded in 1993. Tiny houses on wheels were also popularized by Jay Shafer who designed and lived in a 96 sq ft house and later went on to offer the first plans for tiny houses on wheels, initially founding Tumbleweed Tiny House Company, and then Four Lights Tiny House Company (September 6, 2012). In 2002, he co-founded, along with Greg Johnson, Shay Salomon and Nigel Valdez the Small House Society. Salomon and Valdez subsequently published their guide to the modern Small House Movement, Little House on a Small Planet (2006) and Johnson published his memoir, Put Your Life on a Diet (2008)
In 2005, after Hurricane Katrina, Marianne Cusato developed Katrina Cottages, that start at 308 square feet (28.6 m2) as an alternative to FEMA trailers. Though these were created to provide a pleasant solution to a disaster zone, Cusato received wider interest in her design from developers of resorts, for example.
With the financial crisis of 2007-08, the small house movement attracted more attention as it offers housing that is more affordable and ecologically friendly. Overall, however, it represents a very small part of real estate transactions. Thus only 1% of home buyers acquire houses of 1,000 square feet (93 m2) or less. Small houses are also used as accessory dwelling units (or ADUs), to serve as additional on-property housing for aging relatives or returning children, as a home office, or as a guest house. Typical costs are about $20,000 to $50,000 as of 2012.
Small and tiny houses have received increasing media coverage  including a serial television show, Tiny House Nation, in 2014 and Tiny House Hunters. The possibility of building one's own home has fueled the movement, particularly for tiny houses on wheels. Tiny houses on wheels are often compared to RVs. However, tiny houses are built to last as long as traditional homes, use traditional building techniques and materials, and are aesthetically similar to larger homes.
Some companies have put into motion plans to create tiny home developments.
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While the movement is most active in America, interest in tiny homes has been revived in other developed countries, as well. For example:
This increase in popularity of tiny houses, and particularly the rapid increase in the number of both amateur and professional builders, has led to concerns regarding safety among tiny house professionals. In 2013, an alliance of tiny house builders was formed to promote ethical business practices and offer guidelines for construction of tiny houses on wheels. This effort was carried on in 2015 by the American Tiny House Association. In 2015, the nonprofit American Tiny House Association was formed to promote the tiny house as a viable, formally acceptable dwelling option and to work with local government agencies to discuss zoning and coding regulations that can reduce the obstacles to tiny living.
One of the biggest obstacles to growth of the tiny house movement is the difficulty in finding a place to live in one. Zoning regulations typically specify minimum square footage for new construction on a foundation, and for tiny houses on wheels, parking on one's own land may be prohibited by local regulations against "camping."  In addition, RV parks do not always welcome tiny houses. DIYers may be turned away, as many RV parks require RVs be manufactured by a member of the Recreational Vehicle Industry Association "(RVIA)".
Tiny houses on wheels are considered RVs and not suitable for permanent residence, according to the RVIA. From RVBusiness, "The RVIA will continue to shy away from allowing members who produce products that are referred to as 'tiny houses' or 'tiny homes'. (However, the RVIA does allow "tiny home" builders to join as long as their units are built to park model RV standards.)" 
The financial crisis of 2007-08 fueled the growth of the small house movement. In several cities, an entrenched homeless population formed around "tent cities" or encampments that became semi-permanent housing. Homelessness in these community was driven by foreclosures and unaffordable mortgages from the United States housing bubble.
For thousands who lost their homes due to foreclosure or unemployment, tiny houses became an attractive option. With their low cost and relative ease of construction, tiny houses are being adopted as shelter for the homeless in Eugene, OR; Olympia, WA; Ithaca, NY; and other cities in at least 10 states. Communities of tiny houses can offer residents a transition towards self-sufficiency. Communities that have sprung up, including Othello Village in Seattle, WA, originally lacked electricity and heat. In Seattle, non-profits have stepped in to help provide amenities.
In Reno, Nevada, faith-based groups and community advocates have legislated for new zoning for housing for homeless persons via a tiny home community. The plan would mirror some of the previous above examples. Each tiny house would cost an estimated $3,800 to build, as well as an operating budget of $270,000 for case managers to help residents find more permanent housing and a project manager position.
One challenge besides zoning and funding has been a NIMBY response by communities. Communities may weigh concerns over tiny home communities becoming shantytowns or blighted neighborhoods that reduce property values of the surrounding neighborhoods. For cities such as Chicago that may have lost affordable housing units, tiny houses are seen as an appealing option to close the gap in housing availability. Community planners also have concerns that communities don't devolve into shantytowns such as during the Great Depression in "Hoovervilles".
Smaller homes are less expensive than larger ones in terms of taxes and building, heating, maintenance, and repair costs. The lower cost of living may be advantageous to those 55 and older with little savings. In addition to costing less, small houses may encourage a less cluttered and simpler lifestyle and reduce ecological impacts for their residents. The typical size of a small home seldom exceeds 500 square feet (46 m2). The typical tiny house on wheels is usually less than 8 by 20 ft (2.4 by 6.1 m), with livable space totalling 120 sq ft (11 m2) or less, for ease of towing and to exempt it from the need for a building permit.
Small houses may emphasize design oversize, utilize dual purpose features and multi-functional furniture, and incorporate technological advances of space saving equipment and appliances. Vertical space optimization is also a common feature of small houses and apartments.
As small houses may be attractive as second homes or retirement houses--two out of five people are over 50--their increased utilization may lead to development of more land. People interested in building a small home can encounter institutional "discrimination" when building codes require minimum size well above the size of a small home. Also, neighbors may be hostile because they fear negative impacts on their property values. There has also been opposition based on this fact, due to concerns about increased taxes.
Media related to Small houses at Wikimedia Commons