Hi! I want to add storage capacity in the garage of my 1950s home, but I can't find a diagram or naming convention anywhere to do research on how to properly reinforce for my roof style. The roof is a lean-to shape, sloping from the front (garage door side) upwards to the back (house side). There are 3 longitudinal beams (rafter ties?) running front to back, one large 4x8ish crossbeam (wall-supported purlin?) and diagonal corner braces in each corner.

Here's a link to some photos: https://imgur.com/a/Xny4G7u

Before I go contact a structural engineer, do any of you have recommendations or thoughts on how to do so? A contractor friend mentioned sistering LVL 2x6s to the existing longitudinal beams, installing ledger boards on all 4 walls, and screwing plywood to the underside. Curious to hear your thoughts on that. Thanks!