Level with all custom geometry, players can't build on top of custom geo

I have a level where everything is custom geometry objects from Blender set up as Fortnite Props. However my players can’t build on top of this geometry, what do I need to do to make this work?

Heya have you set up the props through blueprints ?
Make a new blueprint using Building Props, open it up and select the mesh component and add your geometry, then up the top click on class defaults, this gives you a bunch of options to configure in the Details panel including do not block building and structurally support overlapping actors.
It should work, test, get all your settings right first, then duplicate the blueprint and change the mesh component to each object you have.
Replace your geometry with the blueprinted geometry

thanks for the tips! I’ll be sure to give those a go!
I have all the assets set up as Blueprints, so should be easy to replace everything once I get it working.