Natural Cedar decking flooring with Cedar handrails and black balusters. Project cost at approx. $45 – 65K. The cost of this can rise dramatically by swapping the finishes for hardwood decking, cable rail handrails, gas lines, fire alarm beacons, water lines, or by the need for steel beams to support your new deck. A deck of this sizes 10×10 could take approximately 6 weeks to build.