"Christian McArdle" wrote in message
et...
On a quick check a 90x90x3.6mm hot-finished SHS (square hollow section)
Grade S355 (Grade 43) steel would do the job and weighs only 9.6kg/m.

I've just tried it in SuperBeam, and I'm happy with that! At 40kg a beam,
you could carry them up the stairs with a few mates! I bet a square
section
would be really easy to work with, too. It also reduces worries in terms
of
foundation strength. I'd need about 20 of these beams and 800kg doesn't
sound that scary.

How does that weight sound to your walls though ? Mine would definitely
object.