I am trying to estimate the volume of excavation needed for the foundations of a structure from the drawings provided.
The drawings clearly give the dimensions of the RC / cement footing but I suppose the actual excavation will need to be larger than this? How much larger should I plan for in the costing calculations.
Any rules of thumb?
Another issue that comes to mind is that although the RC / cement footing structures are rectangular or various dimensions, any practical excavation would have a slight slope in the walls that increases the excavation volume? Or is that not so significant?