Aluminum floor joists

[mjr6550]

1975 house. I have never seen this before. I could not find any markings on the joists. The odd cross-section makes me think they were manufactured for some other purpose and were surplus. Anybody seen these or have an idea what they may be?

[Rob Amaral]

Where is this? Elkhart Indiana????    Maybe the guy worked at a motor-home factory..

[Greg Booth]

.............in the late 60's, Ryan homes was experimenting with all metal framing, similar to what you're pic shows. I know of only 4 homes done in one of their developments in a Rochester suburb..........Greg  

[Tom Raymond]

Ryan still can't build a decent house with conventional framing. They have no business experimenting with unconventional components. 

[Jerry Simon]

What is your concern, other than the apparent rareness of such?  After 45 years or so, are they failing?

[mjr6550]

On one hand, they look fine. However, I was hired as an engineer to state that they are fine. Nothing is that easy for engineers. Considering the very narrow webs and the lack of any blocking or bridging, I question how they would perform if truly loaded to a design load, or with a concentrated load. Also, I question the performance should a fire occur. they may perform far worst than I-joists, which now have special requirements for protection from fire. 

[Jerry Simon]

6 hours ago, mjr6550 said:

Also, I question the performance should a fire occur. they may perform far worst than I-joists, which now have special requirements for protection from fire. 

I agree; they'll warp/twist.  That's why I prefer a wood beam in most cases versus a steel beam.