King Post Truss Design Question.

Hello all. I found your forum while I was searching for information on the Forestry Forum.

I am a home builder. I'm an experienced stick framer and trim carpenter.

I am currently building a new personal home for myself and it is traditional stick frame construction. My business partner and I have done all the framing on the house. It is a 2,700 square foot heated house over an 1,800 square foot basement. 12/12 hip roof with a couple dormers and several gables. There are a lot of LVLs through out the house, including a triple 24" lvl spanning 24'.

The back screened porch will be 17"-4" wide and 20' deep. It will have a 12/12 pitch.

I would like to use king post roof trusses on 48" centers with 2x6 tongue and grove pine as the roof deck(exposed as the ceiling). I do not want to use a ridge beam. Basically I would like the same design as the lightweight 2x4 trusses we use on 24" centers. Steel plates at the joints instead of joinery.

I plan on sawing the timbers for the trusses from local pine(SYP, longleaf, loblolly)on my Woodmizer.

The home is in northeast Georgia with a 0-10 psf snow load and wind zone 1, up to 99 mph winds(at 53 years old I do not recall a wind over 40 mph here that was not tornado related).

I have several questions.

1. I plan on hiring a kiln drier to dry the timbers. Can a run of the mill(no pun intended) kiln dry timbers or do I need to use them green?

2. What dimensions do I need to use for the truss members? I have seen 2x4 dimensional lumber trusses on 4' centers on a 4/12 pitch with 40' spans using 2x4 purlins on 24" centers.
I was thinking along the lines of a 4x8(actual rough sawn dimensions) bottom cord, 4x8 top cord with 4x6 king posts and braces.

3. I want to use steel gussets cut from 1/4" plate and 1/2 nuts and bolts instead of joinerty. I'll get one of my internet buddies to cut them on a plasma table. Good?

The trusses will stack over 6x6 laminated pine posts rated at 12,000 lbs each. Like these: https://www.menards.com/main/p-1444427703640.htm

I'll use a 4x6 top plate across the columns and bolt the gussets that tie the bottom and top cords together to the top plate of the wall.

Drawing of truss:
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The look of the truss that I want(photo credit to Vermonttimberworks.com ):
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What say you folks that have experience in this sort of thing?

Thanks, Jim

Not a lot of plate work discussed here, mostly joinery. Looks like you need an engineer.

I notice how you have the struts landing on the bottom of the king post, while the photo has the struts landing on the tie. The struts are to carry the load to the king then up to the top of the king into the rafters, a cycle, the king is a neutral member, in the drawing, this is good. Having the struts connect directly on the tie is putting the load through the wrong load path. See the king is held up via the rafters. Maybe with the plates things work a little different, there is still shear in the bolts that need to be calculated, and relish around the bolt holes. The engineer will handle that. It is not just the plates that hold things together.

Those 2x4 trusses are engineered.