A basement apartment is an apartment located below street level, underneath another structure—usually an apartment building, but possibly a house or a business. Rent in basement apartments is usually much lower than it is in above-ground units, due to a number of deficiencies common to basement apartments. The apartments are usually cramped, and tend to be noisy, both from uninsulated building noises and from traffic on the adjacent street. They are also particularly vulnerable to burglary, especially those with windows at sidewalk level. In some instances, residential use of below-ground space is illegal, but is done anyway in order for the building owner to generate extra income. Karel Teige says of the basement apartment under a house that "a basement apartment is a hostile environment and feels like an alien weight, dragging down the poor, serving only if fed by blood and sweat, a place the worker is not allowed to consider as his own home..."
A number of noted artistic achievements have occurred in basement apartments occupied by struggling authors, painters, and musicians.
Ruth McKenney based a series of stories in The New Yorker, later republished in the book My Sister Eileen, on her experiences living with her sister in a moldy, one-room basement apartment above the Christopher Street subway station at 14 Gay Street in Greenwich Village for which she paid $45 a month. The apartment was burgled within the first week during the six months they lived there.
Homeowners will typically rent out basement apartments to tenants as a way to earn additional income so as to offset living expenses. Owning a home with a basement apartment can be an investment. Tenants will provide income to the home owner, reducing expenses, and equity will grow as the value of the property increases.
Basement apartments were the subject of Canadian singer-songwriter Sarah Harmer's hit single "Basement Apartment" in 2000.
In Canada 
In general terms, basement apartments are apartments in the basement of residential houses, with the owner's living space on the upper floors, though there are many examples of basement apartments in older cities as part of older row-house-type buildings and even in older smaller apartment buildings. Even when the house is built on a hill and the basement back door opens onto a back yard, as is the case in some houses and even town houses, they are still referred to as the "basement" if rented, or if the main living spaces of the family are on the upper floors. Modern basement apartments can be quite spacious and large, especially in the case of some of the larger houses built in the suburbs.
Health risks to basement suite tenants 
Some health risks to people who live in basements have been noted, for example mold, radon, and risk of injury/death due to fire. It has been suggested that a basement suite is the last type of dwelling a tenant should look for because of the risk of mold. However, due to demand for affordable housing, basement suites are often the only available housing for some low-income families and individuals, for example in Calgary, Canada.
Airborne spores can cause mold to grow in damp and unventilated areas, such as basements. Presence of mold can lead to "respiratory symptoms, respiratory infections, allergic rhinitis and asthma", as well as personal belongings being contaminated by mold.
Radon is an odourless gas that has been shown to increase risk of lung cancer. In Canada, radon is more common east of the Rocky Mountains, but the level of Radon found in homes can vary widely. Radon levels can be about twice as much in basements as on the main floor of a house. However, home owners are not required to test their homes for Radon gas in Canada.
Basement suite tenants are more likely to be injured or die due to a fire in the house. However, many landlords do not follow fire code regulations, and often such regulations are not enforced by governments.
See also 
- David W. Chen, Be It Ever So Low, the Basement Is Often Home, The New York Times (February 25, 2004).
- Karel Teige, The Minimum Dwelling (2002), p. 105.
- My Sister Eileen, pg. 197.
- "The Tenant's Guide to Mold".
- "Tops and bottoms: State tolerance of illegal housing in Hong Kong and Calgary". Habitat International 34 (4): 478–484. October 2010. doi:10.1016/j.habitatint.2010.02.004.
- World Health Organization Europe. "Damp and Mould: Health risks, prevention and remedial actions". Retrieved 28 September 2012.
- HealthLink BC. "Radon in Homes and Other Dwellings".
- Canada Mortgage and Housing Corporation. "Radon — A Guide for Canadian Homeowners".
- Apartment Ratings. "4 Safety Tips When Living in Basement Apartments". Health & Safety. Retrieved 28 September 2012.
- CBC News. "1 dead in Edmonton house fire". Retrieved 28 September 2012.
- Alberta Health Services. "Charges filed in fatal basement suite fire". Retrieved 28 September 2012.