Further to my previous query we have had our foundation plans through for our extension (yay) and it looks like we will need to make a decision about an instruction on it. I will of course chat with the buildings control officer, architect, ground works people and structural engineer about the most suitable option, but that will take a little time no doubt as everyone is very busy ... so thought I'd get some advice from here in the meantime.
Our house is very old, around 400 years old, timber frame. It had a small existing sunlounge which was added in the 70's. We have taken this down in preparation for ground work as and when. There is an instruction on the foundation drawings saying to check the existing foundation under original house and if less than 600 mm (which I'm sure it will be) then we need to either 'underpin the adjoining wall, use a suspended timber construction or use a ground bearing floor slab (with BCOs approval)'.
To my (uneducated about buildings) eye it feels like the ground bearing floor slab would be the least invasive for our poor old house. Can anyone explain the pros and cons of these options. When we took the original sunlounge down I suspect it was on a ground bearing floor slab, as there was about a foot of concrete under the whole floor area. Very grateful for any information anyone has. Many thanks.