Groundwork & Foundations Question

Foundation difference between a single or double storey extension?

Hi, we are currently planning a single storey extension across the rear of our property which will allow us to extend our kitchen and living room.

However we have been advised to lay a Foundation deep enough for a two story extension, so if in the future we would like to build above this extension we can.

I wanted some advice on foundation requirements and the difference between laying a single or double storey foundation?
Is there a significant cost differences?
Will the building regulators approve and sign off on a double storey foundation even though we are building a single storey?

Any advice will be much appreciated.
Thanking responses in advance.

2 Answers

Best Answer

It's always good advice to lay a dubble story foundation even for a single storey extension as standard if you will like to add later on.

Yes building regs will sign it off its not a problem.

The cost will be more on how much will depend on your builder.

Hope this helps in making up you mind.


Answered 11th May 2016

DPS Damp Proof Specialist

Member since 2 May 2014

for traditional strip concrete foundations, building regulations require a 150 edge distance from your wall. So if your wall is 300 thick (100 block 100 cavity 100 brick) your foundation needs to be 600 thick anyway (assuming its cast directly against the ground on the sides). If you have reasonable ground conditions, a 600 wide foundation will normally be wide enough for a two storey extension. My advice is to lay a 750mm wide foundation, increase in concrete costs will be minimum, no more than £150 quid, that will allow for a future additional storey.

Answered 12th May 2016

ED Planning

Member since 11 May 2016

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