Take your deck spec's to your city or county building inspectors office- whoever enforces the building codes in your area. They'd need to know the footing depth, Post dimensions and placement, the size and spacing of any beams, size and spacing of joists, and size of the decking surface boards. They'd also need to know the materials- pine, fir, cedar, etc.....
Most decks are framed with pressure treated pine of fir, but in some cases cedar may have used, and it isn't rated to hold the same load as pine or fir.
If you have a blueprint at home or on file with the city, that'd make it easy.
