Thanks Will, that jives with my nephew's impression that it is an unusual layout. One of the trusses has the defect you suggest - deflection of the upper chord/straining beam. The lower chords are white pine - ~12"x12" x 45' with little or no wain. the queen posts and upper member and most of the bracing and the hewn rafters are oak (bit of yellow birch thrown in). Main posts also oak - gunstock style I think, but they are almost entirely obscured from view.

There was an oak timber plate that carried the rafters (mortised in) that was eliminated when the building was dismantled and moved. This lowered the roof and required that the queen posts be moved in ~18" and the upper chord shortened.

The roof has leaked and softened the pine timber around the old mortises on the out-of-square truss so perhaps water damage has weakened that one. Some repair has been engineered with lumber and bolts - not really to my liking and I am not sure how effective it has been.... well, it has withstood 220 years of weather and use and some periods of neglect and a move so perhaps one cannot say that the design was defective...

It is a little hard to believe it was a one-off design but perhaps it was... child of king and queen post.

Please explain what 'knees' you refer to as I don't know the terms. The original frame is mostly hewn timber with a few sawn braces, studs and joists - some or many of which are hemlock from the 1830s rebuild.

CB