"Mike" wrote in message
...

wrote in message
oups.com...
Does it not depend on a) how close together the beams are b) if they're
triangulated into the complete roof structure, c) what kind of
unsupported distance they have to span?


Within limits but I think I could just about snap 2.75 x 1.25 with my
hands.


Same here. I would most definitely try to lay more robust joists between
the existing ones, before I laid any boards to walk or store tings on. No
matter how you try to strengthen these joists, you'll still have parts of
the load over just one or two at a time, which isn't really a nice thought.