Good point Chuck. I've lucked out in the past when doing a herringbone border; the room was very close to square. But it was all white oak, so even if it was off a little off, you wouldn't notice it as much. With walnut, it'll be a lot more noticeable.
I plan on doing 3 rows of red oak around the edges of the room, then the walnut border, one more row of red oak around the perimeter, and then all rows on the inside going one direction , like this -
Because of where the border will be, each piece of the border will need a tongue and a groove.
When doing a border like this, on some corners, the tongues and grooves don't match. Where ever there is tongue to tongue, I plan on removing one of the tongues and routing a slot so I get a nice tongue and groove connection. In the past, I've just hacked the tongues off and glued them together
. It has held up to date, but I'd rather have a tongue and groove connection every time two boards meet.
To your point Chuck, because this border is so different in color from the red oak, it will show a lot more of the room is out of square.
I plan on making most outside row completely square, even if I have to taper it a little on one side, that way everything should be completely square from that point inward. Would that look weird in contrast to the wall though if it was severely out of square?