Select the wall which you want to take as a half wall for rendering.

In the design panel, under the "Wall" tab which you will find on the right side of the design panel, you will see an "Advanced" section.

When you click on the drop down next to it, you will see a section marked "Rendering" where you have to indicate Half or Full. If you mark it as "Half" then while rendering this wall will be taken as a half height wall and rendered.

This is useful for the purpose of rendering complete floor plans.
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