Square hip roof doesn't need ties?

[indio]

Does a true square hip roof need rafter ties/joists? I ask because I read the following at a roof related web site:

"Interestingly, a square hip roof, in which all the hips meet at a common point at the peak of the roof, doesn't need ties because the sheathing (the boards, plywood, or OSB that cover the rafters) connects the hips and keeps them from spreading. But a rectangular hip roof has a middle section that acts very much like a gable, and it needs ties to keep the thrust from pushing out the walls."

I have a square hip roof on my garage, so I am interested in knowing if I need ties or joists. Thanks for any info. - Tim

[Rich]

In a perfect world with wind coming from all directions or no wind at all and where snow piles up exactly the same depth on the whole roof - I still disagree :) IMO - gravity usually wins unless the connections are rigid. And by rigid I mean steel - full pen welds (and again perfect world).