A scissor truss is a good choice if you have a vaulted ceiling and want to draw the eye up to enhance the volume of space. A scissor truss accents the ceiling by the use of sloping bottom chords that cross at mid-span.
A timber frame scissor truss does not have a horizontal chord. This gives the area a more visually open appearance. This cathedral-ceiling look has inclined chords, which supports the rafters and ties the members into place.