If you install flooring below grade you re going to run into issues of uneven floors cracks and moisture.
Standard floor thisckness off grade house.
There are many types sizes and configurations of plywood.
Five to six inches is recommended if the concrete will receive occasional heavy loads such as motor homes or garbage trucks.
A subfloor is a wooden structural substrate to which durable finished flooring is attached.
Plywood is usually used as subfloor today.
Joists in home construction are usually made with 2 by 10 or 2 by 12 lumber.
To prepare the base cut the ground level to the proper depth to allow for the slab thickness.
Floor joists are made from 2 by 8 inch or 2 by 10 inch lumber or from engineered quiet beams which are made from a thin layer of chipboard on edge between two lumber caps forming an i shape.
The bulk of the floor s thickness comes from the joists which are the horizontal beams that carry the floor s weight.
Basement floor thickness can be a problem if the concrete is too thin.
Standard concrete floor slab thickness in residential construction is 4 inches.
For example if you happen to move into an old house where the basement floor was an afterthought they may have poured the concrete too thin.