Approved Doc A ambiguity

[bigbadjono]

Hi guys,
I am currently on a construction management degree and i am having a problem with approved docs A.

In order to calculate the width of a strip foundation I must first work out the total dead load per linear metre in kN and apply it to table 10 along with the type of soil and it tells me my width.

I calculated my loads from top of roof to top of foundation and then applied it to the table, this gave me my width, i did not include the strip foundation in my loadings, my instructor subsequently informed me this was wrong. According to him I must include my foundation load as it is a dead load.

My problem with this is that I am using the table to find out my strip foundation width, how can i include the load of the foundation before i know the dimensions of it! Even if i give my foundation a nominal width and depth, say 500mm by 450mm and then stick it in the loadings and say this total loading tells me i need a foundation width of 600mm, i then have to increase my foundation loadings which will then tell me i need a 700mm width, i then need to increase my loadings......and so on.

It is like the snake chasing his tail! The way I see it is that table 10 is there to tell me how wide my foundation needs to be to support the loads imposed on it. How can i include my foundation in the loads?

Any clarification on this would be greatly appreciated as my instructor completely fails to see my point and insists that I include my foundation weight before applying it to table 10.