Measure the dimensions of your deck's framing. Then, draw out a detailed plan of your raised flooring's foundation on paper.
Calculate how to cut your decking. Establish the dimensions of your decking boards -- if you don't have these from your decking's manufacturer, use a tape measure -- and work out how to fit them over your frame. Use a calculator to determine where you to cut your boards when you reach the end of your foundation. For example, if you have a frame that measures 6 feet in length and boards that measure 4 feet, you'll need to use one and a half boards to cover your frame, plus any overhang you require.
Mark your boards where you need to cut them using a set square and pen, and set up your chop saw on a solid, flat work surface.
Put on your goggles, gloves and mask.
Align the guide marks you've made on your boards with the blade of your chop saw and start to cut. You operate a chop saw by bringing the blade down on the item you're cutting.