DEAR TIM: I’m getting ready to build a large room addition that needs a beam to support the floor joists. I’ve been told that a wood beam will work, but I’ve always seen steel I-beams in other houses.

Rust is one of those problems that only gets worse—and more expensive—the longer you ignore it. Whether it’s the frame of a truck, the underside of a trailer, or the tools you rely on every day, ...