On 2008-04-25, Bobk207 wrote:

On Apr 24, 8:12 pm, Wayne Whitney wrote:

This could be addressed by using a pre-cambered beam, like a glulam.

But the ceiling / 2nd story floor would have to be jacked along with
the beam for the entire system to have no deflection....you would
need to enforce displacement compatibility (& a raised starting
point) to prevent a sag when the walls were removed.

Good point. I guess if the joists are unloaded at the time of
installing the precambered beam, it wouldn't be too hard. You could
just clamp/jack each joist to the pre-cambered beam one at a time
before fastening them.

But if the joists are attached to each other transversely at the time
of beam installation, then you have to jack the whole system, and in
the shape of the pre-camber. That could be trouble, but doable.

Cheers, Wayne