Practical Engineering: Sizing Joists for a Hot Tub

This month’s column is in answer to a reader’s letter. He writes: I am building a deck that will hold a fiveperson hot tub. According to the manufacturer, the weight of the filled tub with five people in it will add about 94 pounds per square foot of weight to the deck over a 45- square-foot area. I am concerned about the loads. Even without occupants, the filled tub will weigh almost 3,000 pounds — a constant load on the deck, as opposed to a standard occupant live load, which comes and goes. How can I correctly size the pressure- treated pine joists? Should I use a standard span table? The question is a good