RF Deadzone

Steel beams are not a problem. The 2.4Ghz will go between the beams quite nicely. You may get reflections and multipath, but you will have a signal. I notice your description is devoid of any numbers. Let's try to fill in the details and numbers first:

- What is in between the stell beams?

- How many walls are you trying to shoot through?

- What's the distance between the access point and the dead zone?

- How high a gain antenna did you try? What type?

- What does the 2.4GHz cordless phones have to do with anything?

- Did you try it with the cordless phones turned off?

- Is there any other sources of possible interference in the area?

I had one client trying to make wireless work in a cafeteria full of microwave ovens. Couldn't be done. Another was located right next to the city's new overpowered municipal mesh wireless contrivance. It may not be a shielding issue but may be interference.

I can't really recommend any solutions because I have no clue what you're working with, what you're trying to accomplish (i.e. performance and coverage expectations), what client radios are involved, and what options are available for change.