How to fix non-planar surfaces

I created the top base of a high-rise building, but several rooms could not be built, and a lot of Non-planar surfaces appeared. Is that any way that I can creat this room? Thanks for your help. It is so important. The file download link is on below.

Hi @jackey! Welcome to the forum, and thank you for sharing your model.

I recorded a video for you that shows how you can fix non-planar faces. You should be able to use similar methods that I used here to fix your model.

Let me know if you have any other questions.

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Thanks for your help I will have a try

It seems work for me thanks for your help and patient

Dear sir,
I use your way to fix my model, it works. But when I put the model into the IES. It seems the model got some intersections and External Holes problem. I think only a model with out any hole can be set like a room. So do you know why this problem are shown in this model? And How I can fix it? The Rhino and IES model are all below. Sorry for bother you and thanks for your help.

Plz ignore my new question. I find a way that I can solve it