Strip foundation query

[Dunclane]

We have obtained planning permission for a first floor extension over an existing converted garage.

It all depends on the existing footings so I have dug a trial hole to find this

The walls are cavity walls and there is 450mm from ground to foundation.
The projection out is 250mm and concrete is 300mm thick.

What is the consensus?

[Dunclane]

It's not clear on the photo but the earth can be dug out from bottom of the foundation which is 300mm.

I've asked for a building inspector to have a look this week but just wondered what people's opinions were.

The earth is firm, clay which is mouldable when you squeeze it.

[Dunclane]

Thanks all, I have done a bit of investigating and there are some houses on adjacent cul de sacs of same build that have had similar extensions and looking at the planning website a couple show the same footings as I have so fingers crossed.

[Dunclane]

Good news!

The building inspector came around last Friday and gave it the all clear, we are good to go.

Builder starts next week so keep a look out for the build thread.