foundation trench - do I need a flat bottom?

[Halitosis]

Hi all, I'm digging a foundation trench in the garden today (for a retaining wall) and wonder if the sides and bottom of my trench need to be pretty and straight? I appreciate the top of the concrete definitely does, but as long as it's firm, would a 'wobbly bottom' affect stability when finished?
Cheers

 

[jeds]

It needs to be fairly flat and clean and the walls need to be reasonably straight. If the walls fall away too much you will need to shutter. But it just needs to look reasonable, nobody's going to put a spirit level on it.

 

[Halitosis]

Thanks Jeds!

 

[cjard]

wonder if the sides and bottom of my trench need to be pretty and straight?

No

I appreciate the top of the concrete definitely does

Reasonably does. The nearer the surface the more definitely

would a 'wobbly bottom' affect stability when finished?

Does she know you refer to her like that?

No, you should simply dig in all parts as deep as you need to go to find firm ground