What kind of threshold might work for this 1938 exterior door? It's actually an interior door, and it is exposed directly to weather (there's no porch or overhang). If it were modern wood, it would be rotted by now, but it's the good old stuff.
What's new are 1" thick Dricore tiles coming right up to the door, with carpet to follow. The door will be cut short to accommodate the height. But it needs a new threshold.
The subfloor tiles are 1" high, the door is 1 1/2" thick, the distance from door edge to the concrete edge is 4", carpet thickness is tbd.
The local big box has a product that fits, but with ready-to-rot pine below and really dodgy screws and minimal thermal break:
Or this Pemko product, completely without a thermal barrier:
See also exterior door threshold over distinct concrete slabs at different grades