I recently purchased a house with a high pony wall that divides the dining and living rooms. The pony wall has a column at one end that I'm concerned may be load bearing. To make matters worse, the pony wall is off-center of the vaulted ceiling. A structural engineer wants more than $800 to assess the situation, but I'm not sure if the situation requires an engineer's assessment. If I assume the column is load bearing, is it safe to lower the pony wall to about 3' in height, leaving the column in place? I'll take possession of the house in two weeks and I'm making plan to replace all of the flooring. I'd like to have this resolved before proceeding with flooring plans. Any expert advice would be most appreciated.
I don't believe you need to keep the wall or the post as-is. Here's why.
You have a modern engineered truss roof. Unless all the trusses bear on either a wall or a beam crossing that post, there is no bearing point there in those trusses.
There is no beam resting on that post, under the trusses. No engineered truss system I've ever seen has a single bearing point like that, and no scissor truss has bearing points that near the ridge.
There is also likely no flush beam or girder truss crossing that point. That would indicate a very odd and complex arrangement, which doesn't seem warranted here.
A double stud is a common way to support such a wall. I've built (and removed) many just like it.
Lowering the wall changes nothing about the structural aspects of the home.
That said, you haven't shown the attic. Therein lies the pudding, as they say. I can't be sure about anything I see though an internet tube, of course, but on this one I'm fairly confident.
Theoretically, lowering the wall could adversely impact the column (TLDR, I think that @isherwood is correct). The strength of a column is commonly governed by buckling, where lowering that pony wall's top plate could increase the column's "unbraced length," thereby decreasing its strength. The 1993 World Trade Center bombing, for instance, imperiled the structure by destroying slabs to increase the unbraced lengths of 7 columns by up to a factor of 4.
Obviously your column is unbraced in the direction perpendicular to the wall, but unfortunately you can't conclude with perfect certainty that the other direction's hypothetical bracing is therefore unnecessary. A column's buckling strength is predicated on its "effective length" which varies with how it has been connected at top and bottom. The column could theoretically have connections detailed to increase its strength against buckling in the unbraced direction.
The easiest method to check if the column is load bearing (following @isherwood) is to examine its connection at the ceiling elevation. If there's no pathway for significant compression force to enter the column, then it's not load bearing. Verifying this would require stripping a few square feet of drywall from the ceiling.
There's a 99 point something percent chance that the column is there only to stabilize the pony wall. In your position, I would proceed assuming that the column exists only to stabilize the pony wall. I would verify that assumption early in the remodel process by stripping some drywall from the ceiling and examining the connection as discussed. For an anticipated remodel cost of R and a contractor mobilization plus ceiling drywall cost of D, the expected cost is 0.99R + 0.01D. Worst case scenario? You have to tolerate the unwanted wall.
Again following @isherwood, I would anticipate removing that column entirely. Stabilizing an existing wall like that without the column could be irksome without destroying the whole thing and starting over. Adding a perpendicular wall at the end is a common pattern to achieve stability that could avoid tearing out the old wall entirely.