It’s perfectly doable, and it’s actually a really well tested use case since that’s what Fortnite essentially does in terms of navigation. You need to make sure you have navmesh configured for runtime generation (do that via Project Settings → Navigation Mesh → Runtime Generation) and it should work out of the box.
A word of advice: whenever possible mark the items build-able by player as navigation obstacles (there’s an option for that in Static Mesh editor, in Navigation section of the properties). The upside of using obstacles is that it’s a lot faster to rebuild navmesh tiles. The downside is that obstacles annotate navmesh, but do not create new walkable areas, so creating an AI-walkable staircase with obstacles is not possible.
For more tips regarding tweaking navmesh generation see this twitch stream I did some time ago: - YouTube
Cheers,
–mieszko