i will be laying 3/4" x 3 1/4" hardwood floors in new construction. the subfloor is 3/4" t&g osb, screwed and glued to joists. how important is it to run floor boards at 90 degree angle to, and nailed at the floor joists? it is a good soild floor.
on hallways, does it look odd (big no no) to have the flooring run crossways instead of lengthways?
Yes... nail to the studs. Where you cannot do this (hallway) use a nailing stapler instead. Generally you will run flooring perpendicular to the joist and maintain this direction everywhere. Do not run it lengthwise down the hall.
the installer said that it should be perpendicular to the main entrance for a more pleasing visual appeal.
i had never heard of that, but i don't have an eye for that detail. i am thinking perpendicular to joists should be a goal whenever possible beacuse on the more secure nailing. hallway would look much better lenght ways no matter the joists.