Problem With Creating Slab For My Project

Hi SketchUp Community,

I’m an architecture student at Long Beach City College and I need help to cover the whole bottom of my house to create a slab because it won’t let me.

Can anyone help me, please?

you should be able to load the file now (7th icon)

This is my skp. file of the house I’m modeling. I just need help creating a slab covering the entire bottom of house.
House ADU.skp (3.8 MB)

First you should invert the gray faces you have, you are showing the back side.

Just make a group to the walls and then draw the slab.
What version of SketchUp are you using?