Cement footer - PEM BB building.straw.cementfooter

This is a badge bit (BB) that is part of the PEM curriculum.  Completing this BB is part of getting the straw badge in Building.

While building a house may be out of reach at the moment, let's get some practice putting together smaller structures.  We generally don't like to use cement due to it's high carbon footprint.  But it is a useful material and we can mindfully and judiciously use it at times.  One reasonable option is to use it to make a footer, grade beam or bond beam for a building.

Here are some pictures of what we're after:  
 
 

And here's a nice introductory video of putting a footer on a rubble trench foundation (second half of video):


Minimum requirements:
  - At least 16 feet of footing
  - At least 12" wide
  - Use forms for the sides
  - Rebar included
  - Some of the possibilities are:
         - Atop a rubble foundation
         - Shallow frost protected footing

Provide proof of the following as pictures or video (<2 min):
  - Place where the footing will go
  - Forms placed
  - Finished footing showing dimensions (if not obvious)