Foundation depth?

[hohingday]

Hi,

I am looking into building a 6 metre long, 2 metre high brick internal wall on a ground floor concrete floor, I have had several builders come in for quotes, but I have been getting varying accounts on how deep my existing concrete foundation needs to be to do this? Can anyone advise what would be the normal depth?

Thanks!

 

[^woody^]

If building on top of a concrete floor, what has the existing foundation got to do with it?

 

[Ian H]

It will all depend on the ground below.

 

[London Mike 49]

We had a similar wall built on our concrete floor as a dividing wall and there were no special foundations just straight onto the concrete floor which is about 150 cm thick.

Mike

 

[rssteve]

15

We had a similar wall built on our concrete floor as a dividing wall and there were no special foundations just straight onto the concrete floor which is about 150 cm thick.

Mike

I'm not surprised thats 1 he'll of a floor.

 

[JBR]

It will all depend on the ground below.

Very true.
When I built a lean-to garage, the local building control gentleman, although very helpful and offering (free) advice, advised me that I should dig down about six feet to remove a couple of inches of known peat.
The existing house, incidentally, had stood on that same land for about 80 years, with typically minimal foundations, without sinking!

Hopefully, you might be luckier!

 

[London Mike 49]

We had a similar wall built on our concrete floor as a dividing wall and there were no special foundations just straight onto the concrete floor which is about 150 cm thick.

Mike

Bit of a brain fart there, I meant to type 15cm oops!
And it was only breeze block

 

[Blagard]

If the wall is not load bearing I agree with woody! If the OP has missed off some information such as the wall will be structural then a new foundation through the floor will probably be required. Depth usually depends on the suitablility of the ground.

 

[hohingday]

Thank you for the responses, the reasons for asking was I was receiving varying accounts from different builders about whether the existing concrete foundation could be used... However after consulting with building control, I have been advised regardless of the current floor they would like to see a new foundation laid and will advise of the depth during inspections.

 

[garyo]

Thank you for the responses, the reasons for asking was I was receiving varying accounts from different builders about whether the existing concrete foundation could be used... However after consulting with building control, I have been advised regardless of the current floor they would like to see a new foundation laid and will advise of the depth during inspections.

Any existing foundations that you have will be around the perimeter of the building (or beneath any internal masonry walls). There won't be any in the middle of the floor, so they're not relevant. Why do you need to build the new wall out of masonry rather than timber?

 

[hohingday]

Now you say it like that, it does seem quite obvious!
No real reason for masonry, just a personal preference of a relative.

 

[^woody^]

If you build a timber stud wall it could be built off the slab with no foundations, and be just as strong as a masonry wall. Even if you use ply or cement board lining, it will be cheaper and less disruptive than messing about with foundations.