Concrete foundations in clay soil

[ikearns]

I am looking at building a small brick edged plinth / retaining wall (2m x 3.5m) that can be backfilled and then slabbed to sit a new animal enclosure on.

I am only looking at putting about 2-courses of brick above ground just to elevate the enclosure above the garden in case it rains and puddles form.

The garden soil has a very high amount of clay in it but as the brick is not going to be very high and not carrying a great deal of weight do you think 50cm deep will be sufficient?

 

[noseall]

100mm will be better.

 

[ikearns]

100mm will be better.

Hi there,

10cm?? I was going to go 5x that at 50cm (500mm). So what I was planning was overkill??

 

[noseall]

Severe overkill.

 

[noseall]

Are we talking thickness of concrete or depth of concrete?

I am very tired this afternoon, been a tough couple of weeks.

 

[ikearns]

Are we talking thickness of concrete or depth of concrete?

I am very tired this afternoon, been a tough couple of weeks.

I am purely talking about the thickness of the concrete to put the first course of brick on. I have then read about frost coverage (depth of soil on top of foundations) so I will be putting 2-courses of brick below ground and then 2-courses above ground.

Does this make sense as I have never built a wall before and I am going off what I have read on the web?!?

Doing it this way would appear to use a fair number of bricks so can I use cheaper concrete blocks for the course below ground as I guess one block depth will suffice

 

[noseall]

What you have to remember is a lot of domestic buildings are built on no more than 225mm of concrete.

Blocks (7n dense) below ground will be fine.

 

[Thermo]

Are we talking thickness of concrete or depth of concrete?

I am very tired this afternoon, been a tough couple of weeks.

I am purely talking about the thickness of the concrete to put the first course of brick on. I have then read about frost coverage (depth of soil on top of foundations) so I will be putting 2-courses of brick below ground and then 2-courses above ground.

Does this make sense as I have never built a wall before and I am going off what I have read on the web?!?

Doing it this way would appear to use a fair number of bricks so can I use cheaper concrete blocks for the course below ground as I guess one block depth will suffice

makes no sense to me. the wall is basically being used as a glorified mould to hold the concrete and make it look nice. Depth of footing for the wall are not going to be an issue, nor is frost (too much of mike holmes!) A small foundation of 100mm will more than suffice for 2 courses of brick, that only needs to be just below ground level. It will have more than enough strength as a whole unit once teh concrete fills it in when you do the slab.



Bet im more tired than you Noseall after the last 2 weeks

 

[ikearns]

thermo >> apologies that it makes no sense to you but maybe someone else can assist

noseall >> appreciate your comments

Nothing as fickle as Mike Holmes, just going by what I found on the web http://www.pavingexpert.com/featur03.htm

The brick work is partly for show but mostly practical as I said it is to keep the animal enclosure up from garden ground level

So on review I am going to dig a rectangular trench, as per the lengths in the original mail. The trench will be 200mm (W) x 350mm (D). In the bottom I will put 150mm of concrete as a foundation. On that I will put a 200mm concrete block to bring it to ground level. On top of that I will run two course of brick above ground. Once all 4 sides are built then I am looking to backfill the centre with rubble and hardcore with a 30mm layer of sand to lay slabs on top with the slabs recessed inside the brick border.

When all done then the wooden framed enclosure will sit on top.

Cheers

Ian

 

[Deluks]

Don't forget insulation in the floor, this surely counts as habitable?

 

[noseall]

Bet im more tired than you Noseall after the last 2 weeks

Aye!

 

[Thermo]

thermo >> apologies that it makes no sense to you but maybe someone else can assist

noseall >> appreciate your comments

Nothing as fickle as Mike Holmes, just going by what I found on the web http://www.pavingexpert.com/featur03.htm

The brick work is partly for show but mostly practical as I said it is to keep the animal enclosure up from garden ground level

So on review I am going to dig a rectangular trench, as per the lengths in the original mail. The trench will be 200mm (W) x 350mm (D). In the bottom I will put 150mm of concrete as a foundation. On that I will put a 200mm concrete block to bring it to ground level. On top of that I will run two course of brick above ground. Once all 4 sides are built then I am looking to backfill the centre with rubble and hardcore with a 30mm layer of sand to lay slabs on top with the slabs recessed inside the brick border.

When all done then the wooden framed enclosure will sit on top.

Cheers

Ian

no what you was suggesting was overkill which is why it made no sense, not it made no sense as i didnt understand it.

 

[Static]

Pretty robust animal enclosure.. but sure you only need to really go 450mm down to get below the frost zone, depth of actual footing can be as little as 150mm depending on size of wall your building up.. just make sure the area you put the slab on is fairly well compacted..
The comments others have said are valid tho, but they assume the enclosure is a temporary structure and will have a lifespan of say 10 years.. whereas your building will be there in 25years for the grandkids to enjoy..