Vaulted Porch Roof Ridge Support

[XR250]

Do y'all think I really need to use a structural ridge on this vaulted porch roof? It is a 12:12 pitch and 20 ft. wide. I get the rafter thrust being about 140 plf. i don't want to go thru an onerous detailing exercise to get this to work "by the book" using the adjacent roofs to resist the thrust. I just want to say it is OK and move on. If I use a post to support the ridge, it will be 20 ft. tall - which will be hard to source a straight one. Could go with a glulam post, but they are challenging to get around here in a timely manner.

 

[Eng16080]

I think it's reasonable to use the roof diaphragms to either side of the vaulted porch roof to resist the thrust. If I was going to design it this way, I would simply provide a cleat attached to the vaulted roof used to connect the overlay roof (to either side). I would design this connection for the 140 plf thrust force. I don't see this as being too onerous a task.

Personally, I would just use a structural ridge beam, but I see no real issue with your approach.

One question though: might you want a tall post in the rear porch wall anyway, assuming this is a 20 ft high window wall, and you'll likely need some significant framing there to resist wind?

 

[XR250]

One question though: might you want a tall post in the rear porch wall anyway, assuming this is a 20 ft high window wall, and you'll likely need some significant framing there to resist wind?

It is a screened porch. I forgot to mention that is already mostly framed. Was supposed to have ceiling joists but the owner made a last minute change.