Editing Basement (section)

==Types==
[[File:Piwnice staromiejskie Muzeum Historyczne m.st. Warszawy 03.JPG|thumb|[[Warsaw Old Town|Old Town]] medieval basements in [[Warsaw]]]]

===English basement===
[[File:brownstonebasement.jpg|thumb|[[Townhouse]]s with [[English basement]]s]]
An [[English basement]], also known as a daylight basement or lower ground floor, is contained in a house where at least part of the floor goes above ground to provide reasonably-sized windows. Generally, the floor's ceiling should be enough above ground to provide nearly full-size windows. Some daylight basements are located on slopes, such that one portion of the floor is at-grade with the land. A walk-out basement almost always results from this.

Most daylight basements naturally result from raised bungalows and at-grade walk-out basements. However, there are instances where the terrain dips enough from one side to another to allow for 3/4 to full-size windows, with the actual floor remaining below grade.

In most parts of North America, it is legal to set up apartments and bedrooms in daylight basements, whether or not the entire basement is above grade.

Daylight basements can be used for several purposes—as a [[Garage (house)|garage]], as maintenance rooms, or as living space. The buried portion is often used for storage, [[laundry room]], hot water tanks, and [[HVAC]].

Daylight basement homes typically appraise higher than standard-basement homes, since they include more viable living spaces. In some parts of the US, however, the appraisal for daylight basement space is half that of ground and above ground level square footage. Designs accommodated include split-foyer and [[split-level home]]s. Garages on both levels are sometimes possible. As with any multilevel home, there are savings on roofing and foundations.<ref>Woodson, R. Dodge. Build Your Dream Home for Less. Cincinnati: Betterway Books, 1985, pp 60–61.</ref><ref>Zeller, Dirk. Success as a Real Estate Agent for Dummies. Wiley, 2006, p. 209</ref>

===Walk-out basement===
A walk-out basement is any basement that is partially underground but nonetheless allows egress directly outdoors and has floating walls. This can either be through a stairwell leading above ground, or a door directly outside if a portion of the basement is completely at or above grade. These locations are still considered basements, unless the house is located in Burr Ridge, Illinois. In that case, it is just considered the lowest living level. 

Many walk-out basements are also daylight basements. The only exceptions are when the entire basement is nearly entirely underground, and a stairwell leads up nearly a floor's worth of vertical height to lead to the outdoors.

Generally, basements with only an emergency exit well do not count as walk-out. Walk-out basements with at-grade doors on one side typically are more costly to construct since the foundation is still constructed to reach below the frost line. At-grade walk-out basements on the door-side are often used as livable space for the house, with the buried portion used for utilities and storage.

[[File:daylightbasement.jpg|thumb|A walkout basement]]

===Subbasement===
A subbasement is a floor below the basement floor. In the homes where there is any type of basement mentioned above, such as a look-out basement, all of the volume of the subbasements from floor to ceiling are located well below ground. Therefore, subbasements have no windows nor an outside door. In the homes that have subbasements, all of the basement can be used as part of the main home where people relax and do recreational things, while all of the subbasement can be used for storage. Subbasements are much more common in larger structures, such as commercial buildings and larger apartment buildings, than they are in single family homes. It is common for [[skyscrapers]] to have multiple subbasements.<ref>{{Cite journal|doi = 10.1007/s41062-016-0010-2|title = Tall building foundations: Design methods and applications|year = 2016|last1 = Poulos|first1 = Harry G.|journal = Innovative Infrastructure Solutions|volume = 1| issue=1 | page=10 |doi-access = free| bibcode=2016InnIS...1...10P }}</ref>

Building a subbasement is more difficult, costly, and time-consuming than building a basement as the lowest floor. Subbasements are even more susceptible to flooding and water damage than basements and are therefore rare, except in [[arid climate|dry climates]] and at higher elevations.

Some famous landmarks contain subbasements. The subbasement of the [[US Capitol Building]] is used as storage and that in the [[White House]] is used to store guest items.

===Finished fully underground cellar===
[[File:Sklep cejkovice.JPG|thumb|[[Wine cellar]]]]

According to the international ''[[Oxford Dictionary of English]]'', a finished fully underground cellar is a room below ground level in a house that is often used for the storage of [[wine]] or [[coal]];<ref>Soanes, Catherine and Stevenson, Angus (ed.) (2005). ''Oxford Dictionary of English'', 2nd Ed., revised, Oxford University Press, Oxford, New York, p. 278. {{ISBN|978-0-19-861057-1}}.</ref> it may also refer to the stock of wine itself. A cellar is intended to remain at a constant cool (not freezing) temperature all year round and usually has either a small window/opening or some form of air ventilation (air/draught bricks, etc.) in order to help eliminate damp or stale air. Cellars are more common in the United Kingdom in older houses, with most terraced housing built during late 19th and early 20th centuries having cellars. These were important shelters from [[airstrike|air raids]] during [[World War II]]. In parts of North America that are prone to [[tornado]]es (e.g. [[Tornado Alley]]), cellars still serve as shelter in the event of a direct hit on the house from a tornado or other storm damage caused by strong winds.

Except for Britain, Australia and New Zealand, cellars are popular in most western countries. In the United Kingdom, almost all new homes built since the 1960s have no cellar or basement due to the extra cost of digging down further into the sub-soil and a requirement for much deeper foundations and waterproof tanking. The reverse has recently become common, where the impact of smaller home-footprints has led to roof-space being utilised for further living space and now many new homes are built with third-floor living accommodation. For this reason, especially where lofts have been converted into living space, people tend to use [[Garage (house)|garages]] for the storage of food freezers, tools, bicycles, garden and outdoor equipment. The majority of continental European houses have cellars,{{Citation needed|date=March 2010}} although a large proportion of people live in apartments or flats rather than houses. In North America, cellars usually are found in rural or older homes on the coasts and in the South. However, full basements are commonplace in new houses in the Canadian and American Midwest and other areas subject to tornado activity or requiring foundations below the frost line.

===Underground crawl space===
{{anchor|Crawl space}}
{{Main|crawl space}}
[[File:crawl-space-inside.jpg|thumb|A typical crawl space showing crawl space vents and concrete rat-proofing. Rat-proofing is a thin, irregular concrete covering applied over the soil to prevent rodents from burrowing under the foundation wall and entering the crawl space.]]

An underground crawl space (as the name implies) is a type of basement in which one cannot stand up—the height may be as little as one foot (30&nbsp;cm), and the surface is often soil. Crawl spaces offer a convenient access to pipes, substructures and a variety of other areas that may be difficult or expensive to access otherwise. While a crawl space cannot be used as living space, it can be used as storage, often for infrequently used items. Care must be taken in doing so, however, as water from the damp ground, water vapour (entering from crawl space vents), and moisture seeping through porous concrete can create a perfect environment for mold/mildew to form on any surface in the crawl space, especially cardboard boxes, wood floors and surfaces, drywall and some types of insulation.

Health and safety issues must be considered when installing a crawl space. As air warms in a home, it rises and leaves through the upper regions of the house, much in the same way that air moves through a chimney. This phenomenon, called the "stack effect", causes the home to suck air up from the crawl space into the main area of the home. Mould spores, decomposition odours, and material from dust mites in the crawl space can come up with the air, aggravating asthma and other breathing problems, and creating a variety of health concerns.<ref>{{cite web |url=http://healthlink.mcw.edu/article/926104064.html |title=Mold Allergies |publisher=Healthlink.mcw.edu |date=22 July 2013 |access-date=2 November 2013 |url-status=dead |archive-url=https://web.archive.org/web/20090122072350/http://healthlink.mcw.edu/article/926104064.html |archive-date=22 January 2009 }}</ref>

It is usually desirable to finish a crawl space with a plastic vapour barrier that will not support mold growth or allow humidity from the earth into the crawl space. This helps insulate the crawl space and discourages the habitation of insects and vermin by breaking the ecological chain in which insects feed off the mould and vermin feed on the insects, as well as creating a physical inorganic barrier that deters entrance into the space. Vapour barriers can end at the wall or be run up the wall and fastened to provide even more protection against moisture infiltration. Some pest control agencies recommend against covering the walls, as it complicates their job of inspection and spraying. Almost unheard of as late as the 1990s, vapour barriers are becoming increasingly popular in recent years.{{when| date= October 2016}} In fact, the more general area of conditioned vs. unconditioned crawl spaces has seen much research over the last decade.{{citation needed|date=August 2020}}

[[Dry rot]] and other conditions detrimental to buildings (particularly [[wood]] and [[timber]] structures) can develop in enclosed spaces.  Providing adequate [[Ventilation (architecture)|ventilation]] is thought to reduce the occurrence of these problems. Crawl space vents are openings in the wall which allow air movement. Such vents are usually fitted with metal [[grating]], [[mesh]], or [[louver]]s which can block the movement of [[rodents]] and [[vermin]] but generally not insects such as termites and carpenter ants. One common rule is to provide vents in cross sectional area equal to 1/150 of the floor area served.<ref>2003 International Building Code, Section 1203.3, International Code Council</ref>

Modern crawl space thinking has reconsidered the usage of crawl space vents in the home.<ref name="ToVent">{{cite web|url=http://www.advancedenergy.org/portal/crawl_spaces/pdfs/To%20Vent%20or%20Not%20To%20Vent.pdf|title=To Vent or Not to Vent|publisher=advancedenergy.org|access-date=3 July 2009|archive-date=11 July 2019|archive-url=https://web.archive.org/web/20190711153223/http://www.advancedenergy.org/portal/crawl_spaces/pdfs/To%20Vent%20or%20Not%20To%20Vent.pdf|url-status=dead}}</ref><ref>{{cite web|url=http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11480|title=Crawl Space Insulation|publisher=US Dept. of Energy|access-date=3 July 2009|archive-url=https://web.archive.org/web/20090703122958/http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11480|archive-date=3 July 2009|url-status=dead}}</ref> While crawl space vents do allow outside air to ventilate into the home, the ability of that air to dry out the crawl space is debatable.<ref>{{cite web|url=http://www.advancedenergy.org/buildings/knowledge_library/crawl_spaces/pdfs/Home%20Energy%20January%202005_low%20res2.pdf|title=Closed crawl spaces do double duty|publisher=advancedenergy.org|url-status=dead|archive-url=https://web.archive.org/web/20090124142036/http://advancedenergy.org/buildings/knowledge_library/crawl_spaces/pdfs/Home%20Energy%20January%202005_low%20res2.pdf|archive-date=24 January 2009|access-date=3 July 2009}}</ref> In areas with humid summers, during the summer months, the air vented into a crawl space will be humid, and as it enters the crawl space, which has been cooled naturally by the earth, the relative humidity of the air will rise. In those cases, crawl space vents can even increase the humidity level of a crawl space and lead to condensation on cool surfaces within, such as metal and wood.<ref>{{cite web|url=http://www.advancedenergy.org/buildings/knowledge_library/crawl_spaces/pdfs/Builder%20Online%20Article%20-%202005.pdf|title=Closing the crawl|publisher=Builder magazine Oct 2005 (reproduced by advancedenergy.org)|url-status=dead|archive-url=https://web.archive.org/web/20090210210055/http://www.advancedenergy.org/buildings/knowledge_library/crawl_spaces/pdfs/Builder%20Online%20Article%20-%202005.pdf|archive-date=10 February 2009|access-date=3 July 2009}}</ref> In the winter, crawl space vents should be shut off entirely, to keep out the cold winter air which can cool hot water pipes, furnaces, and water heaters stored within.  During rainy weather, crawl space vents bring wet air into the crawl space, which will not dry the space effectively.