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Groundwork & Foundations

Foundation depth required for building timber frame first floor extension over single skin garage

We are looking to build a timber framed extension on top of our single skin garage. Can anyone let me know the required foundation depth to do this?

3 Answers from MyBuilder Groundworkers

Best Answer

Best practice would be that you dig hole next to wall to expose the foundation, to the bottom of the concrete, although the foundation type will depend on the age of property. Then speak with a structural engineer, for a small fee will let you know if the foundation is suitable, but also being a single skin wall, the Engineer will also assess if the structure can be used for the first floor structure, as there should be brickwork piers at appropriate distances for the wall to be stable to support the new structure. Hope that helps


Answered 20th Feb 2021

Dig trial hole to check garage footings . Then get Structral engineering person to advise accordingly.


Answered 20th Feb 2021

I'm with Tectonic for the most part, but you could ask the engineer if you could use steel framing instead of brick or concrete piers. They will take up less room so that the garage remains more useable.


Answered 2nd Mar 2021

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