A walk out basement is an architectural feature of a house or town home that basically makes the basement space directly accessible from the outside. There are a lot of different names for this feature, and also many different variations. Most of the time, the space is attached to the main house through a stairwell, the same as most any basement would be; the biggest difference is that there is also a separate doorway or stairwell up that connects the space directly to the outside. As such, people can enter and exit the basement directly, without going through the main house. This can be desirable in rental or roommate situations, since it allows for a lot of privacy; it can also be helpful when it comes to moving or storing bulky or dirty items that owners might not want hauled through the direct interior of their living space. Many of these sorts of basements have windows, and often function more like lowered first floors than true basements. Having this feature often adds a lot of value to a home.
In most homes, a basement is room that is essentially underground; it’s usually built into the foundation and can’t be seen from the outside. It doesn’t usually have windows, at least not big ones, and it’s typically designed to be a place for storage. So-called “finished” basements can also be used for entertainment or guest sleeping arrangements, but even these can usually only be accessed through the interior of the house, the same way any other rooms are.
The most distinctive and defining feature of a walk-out model is access to the outside. In most cases this access is “full,” which means that the doorway out is full sized and capable of locking; it’s usually designed to serve as a primary means of ingress and egress, which means that people can come and go without ever entering or cutting through the upstairs.
There are a couple of different ways to structure outside access, and a lot of it depends on how, exactly, the larger structure has been built. Houses that are built into slopes or into the sides of hills or mountains often have full back doors. Daylight basements that are more fully underground often open into small sunken patio areas with stairways that can lead up to street level. These kinds of doors are common on split-level houses without a full floor below ground.
Light and Windows
Standard basements are often pretty cold year round, in part because of how far they’ve been sunk into the ground; hot air also has a tendency to rise, which often keeps it out of these lower spaces. Daylight basements and walk out basements are often much warmer because, in most cases, they’re at least partially above ground and usually have at least some access to direct sunlight. They sometimes also feature full sized windows and can be treated very much like a lower full sized floor, although the ceiling is generally not as high as a normal floor. Things also tend to feel musty and more damp, though opening the door or windows periodically can often alleviate this by promoting the circulation of fresh air.
Value Added and General Desirability
These sorts of basements are often referred to colloquially as mother-in-law basements, in part because of how much privacy they offer. The structures are often used to house roommates or renters without the need to share common areas or doors. Residents of the lower levels will be able to leave the house without ever going through a living room or entering the upper portion of the house. It can serve as a kind of attached, but separate living space.
The nature of a daylight basement can add significant value to a house, as many buyers prefer this type of extra space to a colder and darker basement. Houses are not the only structures that can feature this type of floor, either. Some garages also offer this feature, although these commonly forsake the ability to park a car in the structure or use much room for storage.