Meshes going berserk when extruding I'm working on a project and need to build a house. The basics of the 1st floor is done, but I have to add a foundation to it due to the landscape around the house is uneven, like on a real house.

To make the foundation, I select the bottom vertices of my outer wall on the house, and extrude them downwards, to later separate the extruded part into what will be the foundation. However, when I extrude, the mesh goes berserk, throwing and stretching faces to infinity and beyond. 



Anyone know why this is happening?
Ah, I found the issue. 



I have two entrances to the house, a front door and a back door. To prepare for the extrude for the foundation, I added a edge below the doors, so it would make a face when extruded.

It seems that extruding non-faces is causing issues in Blender, and that's what was causing my issues. 

Removing these edges before extruding works. So I can simply fill the faces after extruding.