Confused regarding foundations for garage

[JamesAsus]

Hi,

Im having my fully integral garage converted into a habitable room, im having it done to building regulations. The garage door has a concrete pad just in front of it, i asked building control what depth the foundations need to be for the front wall and window and they said ideally 900mm deep.

They then said that with it being an integral garage there is likely to be foundations already there, and then go on to say that the builder can just go from the top of that.

Im really confused what any of this means? Are they suggesting my foundations might already be 900mm deep and therefore OK to build off? Or are they saying as long as there is a foundation we can just build on top?

Also when they say they need to see the foundations 'exposed' what do they mean? Do they mean digging a hole that deep to see how far they go? Would this be labour intensive?

 

[23vc]

If there’s already a foundation, and it gets exposed to show its thickness and width, which is a bit of digging for say an hour or so, and they OK it, then you can build off it.

 

[George_engineer]

Sometimes garages don't have a foundation across the doorway, but that is less likely in an integrated garage.

Yes dig a trial pit to see what is there. If the foundation is there across the doorway and is the same as elsewhere (two trial puts needed) then you are ok to build up off it.

Yes digging a hole takes some labour but it's not that bad.