Can I replace the collar ties in my shed with gussets at the peak?

Question

I have one of those bog standard metal prefab sheds. That is I want to say 12x20.

To my understanding, based on the height of the these crossboards, they are collar ties and not rafter ties or joist. And it's my incredibly rough understanding that collar ties do not have a maximum height at which they can be mounted and can be completely replaced with rafter straps.

That being said, can I replace the collar ties with something internal like a triangle cut piece of plywood on both sides at the very peak? Since collar ties do not have a maximum height. Isn't that essentially still just a collar tie? And if so, do I need to use some kind of special screws or what not to attach said boards?

I should note that they are structural plates on each side of the ties, same as the peak.

My goal is just to gain a little more headroom as I'm tall and the ties make me feel claustrophobic.

Answer 1

Without new engineering, no one can say with certainty what can be done. We do not know what loads the roof and walls are expected to withstand. ( wind load and snow weight, etc. as others have said)

The decision to change the original engineering is totally on you. If this were your home I would say you absolutely need to get an engineering report to follow.

That all said, over 50 years in the construction trades, my brain is telling me that 15/32 plywood triangles with a bottom dimension of at least 24" that are bonded with construction adhesive and 1 1/2" construction screws at every 6" and placed on both sides of the rafters would be sufficient. This would most likely make the rafters the strongest part of the shed. However I do not have the math to prove it.

This was the method I was advised to use to modify a truss when I was adding an addition to my home. If it is prescribed by an engineer for my home I would trust it for a shed.