Thermal briging issue wih condensation creating mold is dead ahead.

Wider boards happen all the time. Grain is matched as best as possible and tenons or biscuits let you edge glue the lengths together. Is this a single beam to cover the raised ceiling finish above the railing?

@dan1888 yes it’ll be a single beam and we’ll add one to the peak. My two concerns are the beams looking too chunky and the seams showing where two pieces connect to extend the length.

@zumi my inlaws dealt with that unfortunately! But since that happened, we know what to do properly to avoid that.

Is the reason you went the barndominium route is to save money?

@mark Sort of. My husband works in commercial construction and collected leftover steel from multiple jobs, so our frame was basically free. He framed the structure and we are subbing out the rest.

It's probably too late to do this, but in case it helps others, I would have furred out the other trusses before installing drywall, or done a double layer of drywall, in order to hide that beam on the ceiling. I think a single wood beam will look odd. I would probably just leave it rather than wrap in wood at this point.

@TT yes unfortunately it is too late, and we wished we had done it that way. We are wrapping that beam and adding two more horizontal faux beams in front and behind this one, they’ll be about 15 ft apart.. and then adding one down the peak as well. I think it’ll look better than it sounds!

How noticeable joints to lengthen the boards appear from floor level can depend on the light or dark tone of the wood and how distinct the grain is. Oak has open grain that darkens a lot.

17’ isn’t that long. Are there any lumberyards in your area that have their own mill? I can get up to 22’ if I go right to the mill (versus 16’ at the yard)

17" ( wide")

Nice. You could also paint it with a faux wood finish. I did a faux peach sandstone finish on my foundation stones that came out absolutely beautiful, and nobody can tell that it isn't real.

The front door is faux cherry also