Herr Rabbit is correct but I still hold with "proofed".

The imperial/U.S. adopted units, at least those associated with land, are the foot and acre, but will vary from state to state. If a dimension is greater that 1 foot, then the dimension is in feet. Any quantity greater than 1 acre is acres. So you have 1 foot, then 2 feet and likewise 1/4 acre and 4 acres. Tenths of a dimension are singular in nature. I think the use of foot for dimensions beyond 1 foot and also in square feet(foot) is due to the term footage. There's not a "feetage" term.

Kind Regards,

Raimey
rse