Foundation for an internal garage conversion to kitchen

[Dee12345]

Hi,

Just wanting to get an idea of what is required foundation wise. I am not a builder but have a builder coming to speak about the work and I'd like to have a general idea.

I have an internal garage which I plan to install a door (910mm wide) and windows (1350mm wide). Garage span is about 2.4m wide roughly from memory.

My question is will foundation need to be dug for the wall to be built which the window will sit on? Or will the wall be built on top of the existing floor?

Many thanks

 

[jks7492]

Depends on what's there at the moment - doubt the existing garage slab edge will extend far enough out for you to build the outer leaf of your new wall on?
Might also be a foundation there already - sometimes there's a foundation below the garage door opening even though there's no wall

 

[Dee12345]

ok thanks so in a nut shell until the ground is dug there is no way of knowing if foundation is present or not.

If there is no foundation present, how deep will the foundation need to be?

 

[freddiemercurystwin]

How old is the house? If it's newish (say >30 years old) then there's probably a foundation already, developers generally build a foundation as it's easier to build that little bit than not. But you'll not know for sure without digging down. If there is a foundation take some pics or leave the hole exposed for Building Control to insect otherwise BC will expect a foundation to be built.

 

[Dee12345]

I think it's roughly 1970s/1980s so possibly could be no foundations. Looks like will have to dig to know for sure

 

[Dee12345]

ok so I dug a small hole to see how far the foundations went. I dug about 500mm and there was still a foundation present. Building control confirmed this was ok as it was a party wall. No idea what this means. Does anyone know? If not ill ask them for clarification when he comes on site in 2 weeks. The foundation was strange though. it was basically concrete on top, once I went through the concrete I started digging through layers of red brick. I thought there would be concrete underneath and then red engineering brick built on top of that not the other way around. Does anyone know why this would be?

Anyway more importantly now I got to pour concrete back in the hole, what mix ratio should I use please? 5 to 1 sand to cement? or 6 to 1? Assuming I just use building sand? or do i need for add ballast? if so what is the ration please

 

[Dee12345]

any help out there please?

 

[mikeey84]

If BCO is happy, then crack on. Fill the hole with 6-1 ballast and cement.