Foundation depth

[Mikest]

Whats the best thickness of concrete I should fill my foundation to.
Im trying to avoid drain pipe going through foundation slab.

 

[DevilDamo]

There isn't a best thickness. It depends on a number of factors. However, traditional strip foundations are normally 600 x 300mm thick at a depth of 1m below ground level (to suit site conditions). You could look at increasing the thickness, thus using less blocks below ground level.

 

[landyandy]

I believe 150mm is the minimum thickness. So min 150 below drain and lintel above.

 

[Mikest]

If i fill 300mm with concrete and brick/block rest upto to ground level is that ok.

 

[DevilDamo]

In theory, yes. However, it depends on site conditions.

 

[Mikest]

such as?

How much is a reasonable amount to pour for a strip foundation? I going to have a drain pipe thats going through the ground, i want to avoid lintal over the concrete slab. I would much rather the drain goes through the brick/blocks with a lintal on top.

possible?

 

[DevilDamo]

Such as... subsoil, any trees within the vicinity, etc...

Do you have LABC on this job yet? If so, they should be able to tell.

 

[Mikest]

Ive hit a little problem. The blue is the new extension im building, the black line is the drain. As you see the drain runs right through the foundation but is aslo very close to the existing house wall.

How can i over come this?
My only reason for wanting to put in that foundation is beacuse im gonna be building a 2nd storey on top next year.
I was thinking of doing away with that foundation altogether and just using a steel is that possible?

 

[DevilDamo]

You could go for the easier option and insert some steels to support a possible first floor extension. Then you can erect a non-load bearing stud wall at ground floor level... if you still needed the separation.

As previously mentioned, do you have the LABC involved?