aluminum trusses

Which aluminum is the stiffest for trusses.
currently using hardware store al.(no idea of grade)works alright, but a little flex.
Any info would be greatly useful.
Supplier would be nice to.
Keep looking up
Chuck

ok

Hi Chuck,
5051 would be good or 6061 would have better corrosion resistance. 5051 is used a lot in truck trailers for it's stiffness and ability to handle loads. 6061 is used in aircraft for it's ability to survive stress and rebound and it is excellent for wet conditions.
I guess 5051 might be harder to find in tubing than 6061 though, but 6061 is easy to find. We used 6061 in hang gliders and the down tubes that we held onto were very stiff and strong under compression. It is available in many thicknesses.