Creating conical sloped floor

[sericksonZQUWJ]

I've seen a few forum posts and videos on creating conical roofs, but does anyone know how to create a conical floor? Basically I have a circular structure that needs to slope towards a sump pit in the center. Thanks!

[barthbradley]

Create a Conical Roof and call it as a Floor. Bada Bing.  

Use Roof (or Wall) by Face method. 

[barthbradley]

Wait a minute. Sloped Floor for drainage?  Do you have the ability to Modify Sub-Elements?  That's what I'd use.