I am building a new detached garage, and one corner of the footing was about 1.5" low. To address this, I installed shims between the two top plates, as shown below. The size of the shim increases from left to right to make up the space. This way, the final height is level all the way around the building.
Now I need to secure the trusses to the top plate. For all the other trusses, I was able to use uplift screws from inside.
For the four trusses shown, I installed the screws from above -- otherwise they would not have been long enough to grab the truss. The manufacturer's documentation (pdf) indicates this is allowable:
Is this sufficient? Do I also need to connect down to the plate below? How?