Various, Encyclopaedia Britannica, 11th Edition…
“ Solid strutting consists of 11⁄4 in. boards, nearly the same depth as the joists and fitted tightly between the joists, and nailed in continuous rows 6 ft. apart. Where heavy weights are likely to be put on floors long bolts are passed through the centre of joists at the side of strutting; since this draws the strutting tightly together and does not produce any forcing stress on the walls, it is undoubtedly the best method.Floors are usually constructed to carry the following loads (including weight of floor) ”
