I am a mechanical engineer with Hughes Aircraft Co. in Fullerton. I was reading the Jan. 15 article in Home Design titled "Steeling Home." It talked about the advantage of using steel in place of wood in home construction. It even recommended metal roofing and siding.
I agree that structurally and economically, steel is better and won't be affected by termites, but how do you insulate a metal house against extreme heat and cold?
Wood is a good insulator, preventing sunlight from turning your house into an oven. In the winter, it won't conduct your heat through the walls.
A metal house would require some type of insulating scheme to prevent this.
Also, how do you prevent possible electrical shorts to the structure? A mouse can chew through (insulation of) a 220-volt line and ground it to your house!
Could you please answer these questions?
JAMES M. HENDLER
\o7 Staff writer John O'Dell responds:
\f7 These are two good questions.
Steel framing is made with holes for plumbing and wiring to pass through, and several companies manufacture plastic insulating grommets that pop into the holes to keep the metal edges from touching wires. The grommets meet requirements of the Uniform Building Code.
Steel framing designer Bill Justus said that, in the unlikely event that a wire did break and a bare end did hit a piece of metal stud, there would not be a fire because it isn't a flammable material. "The chances are that it would just short out and pop the circuit breaker," he said.
As for insulation against heat and cold, Justus recommends blown-in insulation, installed after the exterior walls are up and before the drywall is hung.
"It settles into all the nooks and crannies in the wall" and comes in a variety of R-values (an insulating measure) to meet whatever the local codes would require for a steel-framed building, he said.
In addition, builders can use high R-value rigid foam insulating sheets in standard four-inch-thick steel walls or use six-inch framing for the exteriors and fill it with an extra two inches of standard rolled insulating material.
An architect or engineer can determine the R-value of the insulation that will be needed with steel framing in any given locale.