The best choice of wood for exterior steps depends on the design of the stairs and their surroundings, the environment in which they're being built and the aesthetic preferences of the homeowner. Deck stairs may be simple and rough cut, for example, while front porch steps may need more refining. You can use a wide variety of woods successfully in exterior projects, and each has its benefits and drawbacks.
Treated lumber is ideal for projects such as deck stairs, basement steps and steps leading to back porches and outbuildings. Treated lumber is strong and long lasting. It is always a smart choice for ground contact because it resists rot better than most wood products. If you want something more attractive, let the treated wood dry out for six weeks before applying stain or paint.
Purchase pre-cut step stringers from a local home center to simplify the building process. Treated wood also comes in a variety of rails and decorative details you can use to insure the safety of your steps. Use treated decking rated fasteners for all joints to avoid corrosion.
Cedar treads and risers give steps a slightly more refined look. Rough cedar will last almost as long as treated wood. Smooth cedar has a more sophisticated look and is typically more expensive. It is slightly softer with a nice red tint and is prized for its luxurious grain. At more than twice the cost, cedar will definitely increase your budget drastically. Use treated decking screws for all joints to avoid staining. Cedar takes stain well and works better with oil-based rather than water-based paints. It is not typically considered the strongest option for framing.
Exotic hardwoods, such as mahogany or teak, produce more luxurious, craftsman-like results. Expensive but gorgeous, these woods will require sealing and the occasional resealing to maintain their beauty over the long haul. Each of the "rain forest" hardwoods has a distinctive color and grain. Combine them in patterns for an attractive design. Make sure that all screw holes are pre-drilled to avoid splitting.
Build steps from pine if you plan to paint them. Pine is easy to cut, easy to work with and inexpensive. Make sure that pine is well painted to prevent rot from the elements. It is a fairly soft wood with little resistance to rot without paint or stain to seal it.
Make sure that all steps have handrails to prevent falls. Use pre-made rail elements to create lovely railings. They shortcut milling and are designed to meet building code specifications. Make sure that all joints in every exterior wood project are made with treated fasteners to prevent corrosion and staining of lumber.