A basement subfloor is a great way to finish a basement which has a concrete floor. Tim Carter of AsktheBuilder.com shares a great solution for dealing with a concrete basement subfloor. Most basements have a concrete floor and it is easier to work with a wood sub floor as the floor covering. These OSB boards are easy to use and no tools are needed to install. Visit AsktheBuilder.com website for more information.
Design and structural considerations for a basement
Structurally, for houses, the basement walls typically form the foundation. In warmer climates, houses sometimes do not have basements because they are not necessary (although many still prefer them.) In colder climates, the foundation must be below the frostline. Unless constructed in very cold climates, the frost line is not so deep as to justify an entire level below the ground, although it is usually deep enough that a basement is the assumed standard. In places with odd stratified soil substrata or high water tables, such as most of Texas, Louisiana, and Florida, basements are usually not financially feasible unless the building is a large apartment or commercial structure.
Some designs elect to simply leave a crawlspace under the house, rather than a full basement. Most other designs justify further excavations to create a full height basement, sufficient for another level of living space. Even so, basements in Canada and the northern United States were typically only 7 feet 10 inches (2.39 m) in height, rather than the standard full 8 feet (2.44 m) of the main floors. Older homes may have even lower basement heights as the basement walls were concrete block and thus, could be customized to any height. Modern builders offer higher basements as an option. The cost of the additional depth of excavation is usually quite expensive. Thus, houses almost certainly never have multi-story basements though 9' basements heights are a frequent choice among new home buyers. For large office or apartment buildings in prime locations, the cost of land may justify multi-story basement parking garages.
The concrete floor in most basements is structurally not part of the foundation; only the basement walls are. If there are posts supporting a main floor beam to form a post and beam system, these posts typically go right through the basement floor to a footing underneath the basement floor. It is the footing that supports the post and the footing is part of the house foundation. Load-bearing wood-stud walls will rest directly on the concrete floor. Under the concrete floor is typically gravel or crushed stone to facilitate draining. The floor is typically four inches (100 mm) thick and rest on top of the foundation footings. The floor itself is typically sloped towards a drain point, in case of leaks.
Since heat rises, basements are typically cooler than the rest of the house. In summer, this makes basements damp, due to the higher relative humidity. Dehumidifiers are recommended. In winter, additional heating, such as a fireplace or baseboard heaters are required, though in Canada forced air furnaces effectively equalize the whole house's environment.
The finished floor is typically raised off the concrete basement floor though modern laminate flooring is typically placed on concrete floors in Canada with a thin foam underlay. Radiant heating systems may be embedded right within the concrete floor. Even if unfinished and unoccupied, basements are heated in order to ensure relative warmth of the floor above. It is recommended that the basement walls be insulated to the frostline. In Canada, the walls of finished basements typically are insulated to the floor with vapor barrier(s) to prevent moisture transmission.