Deerhunter,
When you stand up an exterior studded wall it has a bottom plate and a top plate. A second top plate is added to lock in adjoining walls and strengthen the carrying capacity of what is usually where the trusses sit. By overlapping the joints of the first top plate you create rigidity.
In my case, after the second top plate was added, I then put the exposed beams in place resting them on that second top plate. On top of the beams and directly over the other top plates, I then did an additional two courses of plates creating the "beam sandwich". It is on top of that second layer of doubled plates that my trusses rest. The ceiling 1x12's are nailed to the top side of the beams inside the perimeter created by the second layer of double plates BEFORE the trusses are put in place.
The beams were set on 16" centers. They are 6" square beams that means there is a 10" space from the side of one beam to the one beside it. It is overkill to say the least, but it is the scale and appearance I was looking for.
It was a cheap solution to the beam application and had additional benefits. Easy to work on setting trusses as you are walking on a flat secure surface and extra strong side walls to carry trusses and handle snow loads. The beams cannot twist over time because the beams are locked in place. The only extra cost was for the second double course of top plates. Just as some people add an additional layer of block to the foundation wall to gain headroom in their basement, it was money well spent.
This was my own idea, but I would bet it has been used elsewhere.
