According to the Steel Recycling Institute, the overall steel recycling rate for 1995 was 68.5 percent. This saves on valuable energy and natural resources. Each year, steel recycling saves enough energy to electrically power about one-fifth of the households in the United States (or about 18 million homes) for one year. Every ton of steel recycled saves 2,500 pounds of iron ore, 1,000 pounds of coal, and 40 pounds of limestone. For more information about steel recycling, call the Steel Recycling Institute at 800-876-7274.

There's also another factor to consider: Steel increases thermal bridging through exterior walls, which actually makes heating and cooling less efficient. (Look back to "Mortarless Block Systems" in Chapter 3.) But installing insulated exterior sheathing to create a thermal barrier can reduce heat transmission through studs and improve the thermal performance of walls. And the American Iron & Steel Institute (AISI) points out that steel framing results in less air loss around windows and doors as well as foundations and roofing connections.

I also wonder if this increased thermal bridging has anything to do with the dark vertical lines (ghost marks) that sometimes appear on walls where the steel studs are located. This can be a problem if you don't properly insulate the wall to create a thermal break. The AISI publishes the "Thermal Design Guide for Exterior Walls" that addresses this issue and provides solutions.

Don't get me wrong – steel has been used successfully for years in the commercial and industrial market where construction methods are different than they are in the residential market. It's more economical to achieve strength, noncombustibility, and design versatility with steel and concrete. But in the residential market, steel is a real newcomer.

My experience using steel made me wonder whether or not we can continue to use the carpentry and woodworking tools we already have if we expand into using this material. I looked into it and learned the answer – we need to equip ourselves with metal tools such as electric shears and/or nibblers, chop saws, hole saws, screw guns, and C-clamps and seamers, just for starters. However, I don't consider these minor additions to the tools we use a serious barrier to using steel.

The bottom line is that if you plan to use steel framing systems in your projects, you need to educate yourself to understand them. That's the only way you can use them efficiently. And that also holds true for building officials, engineers, and architects.

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