below grade footing

[dabill]

My addition will be on a slope which requires the footings to be a max of 18" below grade. I am considering a trench footing but do not know how to make sure it is level. Can you help me?
Thanks

[Rich]

I would use a step footing. Where it will go for however long horizontal and then drop 18"..etc. Footings on a slope are not good. Think of a ski - point it downhill and pretty much, no matter the surface, it will go downhill. The same goes for a sloped footing. I also disagree with the 18" depth max. With an 18" depth you may need to be worried about frost - not sure your location.
As far as making it level just use a builder's level (eyepiece) as you pour it. That is if you are bank pouring - no forms.

Maybe I'm not understanding your question - it's been known to happen. :D