It seems that steel would be stonger and more stable than wood, fire resistant, and better for the environment, so why are most homes wood-framed rather than steel-framed?
Basically, it's because wood was available first and wood is still the cheaper, more widely available material. Way back when man started building dwellings similar to what we have now, steel was not an option for the masses. The process probably hadn't even been invented or perfected yet, there was not the widespread transportation of goods that we have today either. Early shelters were not even put together with nails, they use wooden pegs because metal was so expensive and not widely available. I can't say that it would be better for the environment; it takes a tremendous amount of electricity to smelt and produce metals. And you have the emissions problems from the factories and the power generation. I'd have to do more research on that one. A managed timber stand actually reduces greenhouse gasses and every scrap of that tree can be used in one form or another. The only energy expenditures are moving the trees to the saw mill, cutting at the saw mill and transportation of the goods after that point. And that would be a lot less than the power required to make the same number of feet of steel products.
Steel cost more and is very heavy. It would take a piece of equipment to put each piece in place. Holes would have to be made in the steel. Nails will not go into steel. How would the foundation be made?
In most locations a 2x4 is slightly cheaper than a steel stud. The labor is cheaper with wood because it's less skilled and there are many people to swing a hammer cheaply. Most contractors do what they know and most only know wood.
Because it's always been done that way. Never underestimate inertia when asking why new materials/techniques are not adopted. Besides, the cost does not give steel a clear advantage. You can drive a nail anywhere into a stud. With steel, you have to drill your holes precisely.
