How to reverse all these blue (backward facing) faces? The complicated thing is that the other faces of the model are correctly oriented

I heard that blue and white faces are rendered differently (by Vray) so I want them to all face forward but the extension that helped me protruding these floor slaps all at once left them with both forward-facing and backward-facing faces. Searching for a solution for this problem, I’ve found two extensions that can do the job but one (https://sketchucation.com/forums/viewtopic.php?f=323&t=44551) is paid (I can’t afford it right now) and the other(https://sketchucation.com/pluginstore?pln=Vbfr) is really troublesome to install (and it also not quite good at doing its job (https://www.youtube.com/watch?v=pdQw-AgGrhs)). So I would very appreciate any help from you guys, thanks a lot!

It depends on how the model was created. Did you use components for floors? Did you make them groups or did you just make one group for all the geometry?

Because the building has a lot of setbacks so I don’t use “make component”.

Actually, that would work fine for my case but imagine a skyscraper likes the Shard with each floor different from another

SketchUcation offers a free membership, allowing access to most aspects of the site, but without some benefits like Shop discounts etc given to paid members…

Fredo’s extensions in SketchUcations PluginStore are also free to download, install and use.
The only complication with Fredo’s extensions are that most of them also need this LibFredo installing, which supplies shared code etc.
But that’s also freely available…

Why do you believe it’s ‘paid’ ??

The second one you linked is also free to download [but Fredo’s is better IMHO]

My fault, I didn’t check the site carefully, thanks!