Sep 02, 2021 · DATE: 2021-09-02. industrial die cart with stand-off deck 30 ton. Calculate Deck Load Capacity – Tributary Area now Let’s find the tributary areas of a deck. To determine the maximum load capacity of your deck, start by calculating its total area and multiply by 50 psf. So, a 100 sqft deck would be designed to support 5000 lbs.