Scarf Joint location in load bearing top plate

[Hackermatack]

I have done a good bit of timber framing but am by no means an expert. I have in the past always tried to locate my wedged scarf joints as close to a supporting member as possible. The building that I am going to work on next will be posted every 10' so if 16' timbers are used for the plate it will be almost impossible to keep them all close to a support. The plate will have considerable snow load as it will be timber framed sidewalls with a standard 40' clear span truss. Every other 10' bay will be open and the next will be solid vertical boarded which will add some strength to those bays. I am sure this type of joint is quite strong for vertical load but no way can it be as strong as a solid timber just wondering if anyone knows how much strength is lost? Not particularly worried about it as the posts and plates will be 8 x 8 and with a 24" OC spacing on the trusses every 5th truss will land on a post and the truss either side of it will be nearly over a brace.

[beenthere]

The bending moments considered, then there is more strength when the joint is not near (or over) the post. IIRC about 1/3 of the way out.
But our resident expert @Jim_Rogers can answer better.

[Jim_Rogers]

I have written many posts about scarf joint locations here on this forum. You could/should do a search for them if you haven't seen them already.
As to how much you actually loose, that's a tough engineering question that I am not qualified to answer.

Jim Rogers

[canopy]

There is also a thread here about some engineers that tested to failure various scarf joints vs a solid beam and published the results. May not answer your case specifically, but give some idea. Best to get an answer from a timber frame engineer.

[timberwrestler]

8x8s spanning 10', with 40' trusses on them are a little thin.  At 40 psf snow load, the 8x8 has about 1/2 of the bending strength needed.  I don't know what your ground snow load is, or the roof pitch, or roof material, so it could be a little higher or lower.  It'll 'probably' be OK, but not by the book.  Of course, you don't have a book in NE VT.

[Hackermatack]

I will have to research that a bit, seems like the braces would transfer some of the load back onto the post. Guess we could go with 8' bays and make all of the splices on a post with a thru tendon.

[beenthere]

Don't think you want the splices on the posts.
Do some more research... and think you will find out why.

[jimdad07]

Any way you can upsize the beams?  You may not be happy changing your floor plan just to accommodate the beam sizing, the beams should be sized to accommodate the space you want and the loads that are planned.