900 King St W | 25 fl | U/C

[K.P.]

My guess is it is for the service elevator once it is erected

95% sure the wood walls are a requirement to protect the hoist way for construction hoist. Same with the wooden overhang its to protect workers waiting for the hoist.

On a similar note to the TEK tower discussion, the tower crane and the hoist always creates a small problem, GC/concrete contractor have to pick between the lesser of two evils.
On this project, looks like they will have to infill the first two cast in place floors where the hoist location is, otherwise it wont align with the tower.