Foundations

[spynage]

I'd like to build an extension at the back of the house in the picture.

My question is. Considering the house is on terraced land. Would the side abbuting my neighbours house require foundations dug to the same depth as theirs? ie I'm concerned that the foundations if dug down to just 450mm would effectively have no horizontal support apart from my neighbours lean-to.

lean-to. Is this adequate to stop slippage?

 

[tony1851]

No, it would probably impact on their foundation and wall, which is contrary to Building Regs.
In practice, you would need to go down at least to the same depth as their footing.

 

[^woody^]

...... and at least as deep as the drains

 

[spynage]

Thanks. That's what I was expecting to hear.

Will the other walls be ok with 450mm depth foundations?

 

[Ian H]

It depends what ground your
down to at 450, sounds very shallow to me, you might still be in the top soil.

 

[spynage]

Thanks. I think I have the information I need now. Can you recommend any further reading for extensions or foundations?

 

[tony1851]

Thanks. I think I have the information I need now. Can you recommend any further reading for extensions or foundations?

Google 'Approved Document A' - this has plenty of simple line drawings showing foundations.

 

[Constantin Marin]

Are you digging into clay? Any trees close to the foundations? Quite a few factors you need to consider. You should find a chart on your local council website where you input the soil type, trees distance and type etc. and it will give you a min depth. Never dug any foundations less than 800-900mm deep

 

[tomfe]

Foundations can be as deep as 0 if you're building on rock. You only need to go down to suitable ground even if you have trees nearby, 'bedrock' (rocky soil) some places is quite close to the surface.
Frost level in granular material in the UK is 450mm. However I've seen rafts and exposed slabs much higher.

 

[^woody^]

Foundations can be as deep as 0 if you're building on rock.

A prize for anyone that knows of a UK suburban semi built on rock.

Doubled if it has no foundations.

Quadruple-bazoopled if the attached semi has been dynamited into the bedrock.

 

[stuart45]

My last house was.
https://www.tripadvisor.co.uk/Attra...ichael_s_Mount-Marazion_Cornwall_England.html

 

[^woody^]

My last house was.
https://www.tripadvisor.co.uk/Attra...ichael_s_Mount-Marazion_Cornwall_England.html

Disqualified. Not a semi. Please follow the rules.