Don't use MDF as sub-flooring! It doesn't handle moisture at all. It's just an adhesive and dust compound and will corrode quite fast underneath a floor where air circulation is minimal. It's also very dense, so it requires excessive nail width (7d or so), which damages the surface of the flooring above it. MDF is primarily used for cabinetry millwork or external surfaces that will be finished with a vapor retarding paint or laminate to stop any potential exposure to water.
If you're going for economical subflooring instead of engineered wood, you want OSB (Oriented strand board) joists with cedar or pine furring strips on top. They dry much quicker, deter insects from penetrating the floor, and are soft enough to also allow you to use minimal nails (4-5d) to conceal the joinery's visibility.

If you're going for economical subflooring instead of engineered wood, you want OSB (Oriented strand board) joists with cedar or pine furring strips on top. They dry much quicker, deter insects from penetrating the floor, and are soft enough to also allow you to use minimal nails (4-5d) to conceal the joinery's visibility.













