Measure the width of each tread from end to end. If the steps vary in width, note the widest step on the staircase.
Place the tape measure on top of the tread at the front edge and measure to the back of the step where the next stair begins. If the treads vary in depth, note the deepest tread on the staircase.
Determine the width of each stair riser. Place the tape measure at one end of the riser and measure to the other side. Write down the widest riser measurement.
Hold the tape measure at the point where the tread intersects with the riser and measure to the point where the tread intersects with the riser above that step to find the height of each riser.
Count the total number of steps in the staircase. Provide the builder or your wood supplier with these accurate measurements to acquire the appropriate amount of wood for the project.