Rust/Structural integrity

I am having a house built and the builder will install two steel I beams in the basement to support the two upper floors. The I beams seem to sit outside for a few days prior to installation in the other homes so the same will happen to mine. How long before the I Beams rust to the point of losing their structural integrity?

If it was me, I would tell the contractor that the I-beams should be primed. Why should you be left with prep issues if you want to paint this beam in the future.

Stress and strain calculations are a fairly complicated issue that cannot be answered in terms of the number of days of exposure, but realistically this is absolutely the very last thing I'd worry about in the building of your home. Chances are the beams could be left outside to rust for a decade or more without any structural problem for a house, and even then any problem would be almost surely be excess flexure rather than outright failure. I-beams are usually greatly oversized, and steel is a very ductile material. While I certainly haven't heard of everything, as an engineer for 35 years and a home inspector for a while, I've never heard of a problem with an I-beam support for a house. Worry about the stairs and about termites :-)

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey