2m deep foundations/concrete?

[SS-ProjectBuild]

Hi all,

Im about to endevour on a new journey to project build my outbuilding at the bottom of the garden. I have been reading this forum for a few months now researching etc. The site is nearly cleared and i am ready to mark up for the digger.

There are some Sycamore trees dotted around so i envisage BCO will ask for 2m footings - somso first question is.....in 2m trench how deep do you recommend the concrete footings be? Standard i know is circa 450mm so could i assume it would be double this?

Thanks.

 

[23vc]

Depends if you want to be laying blocks underground, generally easier to mass fill to near ground level. Large/habitable outbuilding then if BC involved?

 

[stuart45]

Is the ground shrinkable clay?

 

[SS-ProjectBuild]

The BCO hasnt hasnt been out yet but my area is believed to be medium clay content.

 

[SS-ProjectBuild]

Depends if you want to be laying blocks underground, generally easier to mass fill to near ground level. Large/habitable outbuilding then if BC involved?

Yep ive hired a council approved private firm so they are more accessible as im am self project managing.

 

[frutbunn]

In my experience they are almost always mass filled but you may need to use clay boards.
How far away are the trees and which part of the UK? I can give you an idea of depth

Yep ive hired a council approved private firm so they are more accessible as im am self project managing.

I wonder why we we were getting so many contractors back using LA's. Particularly after the Aedis debacle!

 

[SpecialK]

https://info.labcwarranty.co.uk/foundation-calculator

 

[SS-ProjectBuild]

In my experience they are almost always mass filled but you may need to use clay boards.
How far away are the trees and which part of the UK? I can give you an idea of depth

I wonder why we we were getting so many contractors back using LA's. Particularly after the Aedis debacle!

Im based in the west midlands (sandwell)

 

[johnny2007]

Some well respected builders here are suggesting 200mm concrete on mud.
My (wrong?) advice is to seek advice from BC as they're familiar with the area and some of them are even engineer, rather than jack of all trades.
Also, the architect drawing your plans might be familiar with requirements for your area as well as trees nearby.

 

[SpecialK]

My house is built on a 200mm strip foundation in a 1.2m trench in clay. Poor sods had to use block work to get it to ground level.
You wouldn't want to be laying block work 1.8m underground in a 600mm trench - So its best to fill the whole trench with concrete. This is what I will be doing with my extension, more cost in concrete but less labour for a brick layer and I don't need to find material to back fill the trench.

100% correct advice to seek guidance from BC, you wouldn't be allowed to fill the trench without them checking first anyways... (unless you didn't want a completion cert)

Some well respected builders here are suggesting 200mm concrete on mud.
My (wrong?) advice is to seek advice from BC as they're familiar with the area and some of them are even engineer, rather than jack of all trades.
Also, the architect drawing your plans might be familiar with requirements for your area as well as trees nearby.

 

[Charlie George]

Some well respected builders here are suggesting 200mm concrete on mud.
My (wrong?) advice is to seek advice from BC as they're familiar with the area and some of them are even engineer, rather than jack of all trades.
Also, the architect drawing your plans might be familiar with requirements for your area as well as trees nearby.

If's thats a dig at Noseall,your'e wrong, nowhere did he mention that,and theres no requirement to mass fill, builders do it because it's easier,225mm is the standard for most house foundations.

 

[stuart45]

9 inch concrete used to be the standard until foundations started getting deeper(after the summer of 76). Trench fill was quicker and safer in a deep trench. Building regs allow less in certain cases.

 

[Charlie George]

9 inch concrete used to be the standard until foundations started getting deeper(after the summer of 76). Trench fill was quicker and safer in a deep trench. Building regs allow less in certain cases.

May well be an area thing,up in NW of England it was 200mm until recently then increased to 225mm,i very rarely build house's on anything deeper than 1000mm dig out, and can count on both hands the times i built off mass poured, usually extensions with awkward access.

 

[SS-ProjectBuild]

Thanks guys - it will be a trench fill foundation as oppose to strip. Thats going to be a lot of concrete - just had a long hard slog and removed the concrete posts and gravel boards in the proposed area. You can see the 2 sycamire trees on the right in the photo.

 

[SpecialK]

Pop the details into the calculator I posted the link to above and it will give you an approximate foundation depth...

Thanks guys - it will be a trench fill foundation as oppose to strip. Thats going to be a lot of concrete - just had a long hard slog and removed the concrete posts and gravel boards in the proposed area. You can see the 2 sycamire trees on the right in the photo.