50 lb. per sq. ft. (psf); (40 psf live load, 10 psf dead load). 3. The load-bearing capacity of the soil (assume 3,000 pounds for Hoffman Estates). How to calculate the load? by half t In inches pier needed to carry the load. In the example pier As indicated in the deck design shown in fig.1, using 4 piers allows a span of roughly 6 ft. The maximum