Groundwork & Foundations Question

How wide are extension footings

i am planing a single storey extension build and wondered how wide the foundations will be. I know they will need to be a 1m deep

10 Answers

Best Answer

the standard minimum size should be 600mm wide for a standard width cavity wall of 300mm. (100mm brickwork, 100mm cavity, then 100mm blockwork). there should be a minimum of 150mm of concrete at either sides of the walls to = 600mm in total

but all jobs and ground conditions vary, so your best advice is to check with your local building control which can be contacted through your local council.

Answered 21st Nov 2011

Walkden Bricklaying

Member since 17 Nov 2011

the standard footing width with a 100mm caverty wall will be 450mm, make sure to consult plans because this may vary due to ground condition and type of footing all info should be on a comprihensive set of plans,

Answered 21st Nov 2011


Member since 21 Nov 2011

600mm is the expected width and one mtr minimum depth

Answered 21st Nov 2011

Affordable construction

Member since 28 Sep 2011

Typically 450mm wide. That will allow for,
Brickwork - 100mm cavity - Blockwork
And depth just depends on ground condition, 600mm would be good enough if you hit good clay..

Answered 21st Nov 2011

James White Brickwork

Member since 13 Dec 2010

the best way to find these details out are to give the local building control officer a call as they will be more than helpful for you

Answered 21st Nov 2011

S1 Builders Norfolk

Member since 10 Nov 2011

Normally 600mm wide.

Answered 21st Nov 2011


Member since 29 Oct 2008

Normally 450mm but its dependant on ground conditions.


Answered 21st Nov 2011

R.Hughes Building and Conservation Ltd

Member since 25 Feb 2009

Your footings will need to be 1metre deep & 600mm wide.Unless you have any issues,Your building inspector will advise you on this.

Answered 21st Nov 2011

m w building construction and property maintenance

Member since 28 Sep 2008

they are generally 600mm wide but check with you Building Control Officer

Answered 22nd Nov 2011

Clarity Home Designs Limited

Member since 27 Sep 2010


Answered 22nd Nov 2011

Dawn Construction

Member since 19 Jan 2011

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