The wood floors in the house above this between-floor cantilever (overhang) were always cold in the winter until Triple H spray foamed under the cantilever. Each bay was completely empty an uninsulated when we opened it up. There was good reason for the floors to be cold. Cold air was also getting in the house, mixing with the warmer conditioned air making it more difficult to heat and keep an even, comfortable temperature.
The floors are now are as warm as in the rest of the house. Spray foam both insulates and air seals and will also keep the cool, conditioned air in the home in the summer.