Hey Ken and Dick

I've tried to check hay density figures and have found that results will vary. The heaviest per cubic foot bale offered for sale was a high grade alfalfa bale 15" x 18" x 36" weighing 80 lbs. That is 14.2 lbs. per cubic foot. Hay, as a commodity, is sold by the ton and to grade standards. Farmers engaged in the sell of hay as a commodity should know the bale weight. Lacking input from a supplying farmer, a local farmers co-op should be able to give a good idea concerning your local market. Grain density is much greater, wheat berries weigh about 48 lbs/cubic ft.

The 1842 Penn. style barn I am currently working has floor joist hewn on opposite sides 8 inches deep with a min 10" width on average 36" centers spanning 9' to 10'. Longitudinal beams are 10 x 12 with posts every 10 feet.

The standard of 300 psf min. turns up in a 1958 handbook.