Confusing concrete situation for LVP flooring project in ground floor room with patio door

Last week, I pulled up all the carpet in my ground floor bedroom/office (in a 3-floor townhouse), with the intention of laying down luxury vinyl plank flooring. Most of the process seems fairly straightforward and in line with all the videos and articles I've found. However, I'm a bit stumped on what's going on in the ~6 inches of space adjoining the sliding glass door and wall to the backyard patio... The smooth concrete slab that serves as the subfloor for most of the room suddenly tapers off and reveals a wood beam (2x4, 2x8?) and a much rougher stretch of concrete next to the door. There's also a fairly stark gap between the beam and the rough concrete. Pics below. Is this normal? If so, how should I handle the transition from the LVP flooring to the sliding glass door? Do I need to smooth or fill or do anything else in that ~6" stretch, or should I lay the planks as normal and add some basic threshold molding? Any input or advice would be greatly appreciated! Side angle, from left to right: smooth slab, 2x(something?), gap, rough concrete, flashing, sliding glass door ​ Front on view: showing transition from smooth to rough slab; the latter may be the same as the concrete sidewalk outside... I can't really tell. submitted by /u/jaeddy [link] [comments]

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