viable alternative to wood joists

[xelaris]

What is the equivalent structural alternative to wood joists for a suspended floor?

I've recently come across some wood beams made from recycled plastics:
https://www.filcris.co.uk/product/heavy-duty-grey-80mm-x-160mm-x-15m-beam-rg0816150

but maybe there are already tried and tested alternatives like steel, concrete or aluminium beams?

Any suggestion very welcome.

 

[tomfe]

Steel, concrete are alternatives, you could also use aluminium. You might beable to use spaghetti depending on span.

What is your real question?

 

[chappers]

and why two threads on the subject

 

[xelaris]

that thread was about plastic joists...then I've expanded the horizon and that's why this thread. Maybe the 2 can be joined together?