It's a fairly good concise term ... load-bearing, even. /ducks

But even then, I think "boundary" was the more common term before some LLM decided it really liked "seam" instead.

In architecture, a seam is not load bearing. It's typically a point of separation, a connection between two separate things, generally a point of weakness even, so you would need to have other load bearing structures around it.

"Load-bearing seam" doesn't make any sense.