Expansion Joint at Interior Partition

[Nat]

Hello Everyone!
I'm working on a renovation project for a commercial office (Michigan, 2018 IBC). The existing building expansion joint runs through the break room, right in front of the millwork. See the link below for photos.

My question is about the two walls on either side of the millwork. The contractor said he "float" the walls over the expansion joint by not securing the bottom track. His opinion is that this will allow the vertical exp jnts on those walls to be eliminated. I asked about slip-track and he said that's not needed since the walls don't go to the deck. While this is true, the walls do connect to soffit framing above, which goes to the deck.

This is a high-end renovation and everyone would love to eliminate those expansion joints, but I'm concerned that the contractor is just trying to find an easy way out. Is this a legitimate solution? I don't have much experience with expansion joints. Any advise is greatly appreciated.

https://www.dropbox.com/sh/gif5w0jzm9m40cn/AAAAoW0auE0lW_v7qmahr1b7a?dl=0

 

[e hilton]

I thought slip track was for vertical movement at the top of the wall.
Here’s what i would do ... looks like the millwork is going to sit behind the expansion joint. So build the side walls full depth, with a continuous bottom track, but raise the track 1/4” off the floor ahead of the joint and let that last foot float. Might have to add a layer of ply to act as a shear wall. Basically you would be building a version of a torsion box, fastened to to wall behind the millwork and the floor behind the EJ.