Extension foundation question

[whereeverilaymycat]

Hi everyone sorry if this is a daft question.

I'm sure when we moved into our house we were given paperwork to do with the extension they had built, only I can't find it anywhere. I am wondering whether it would be possible to build on top of it (currently single height) and if I can't find the paperwork, how I'd find this out? Would a builder somehow know? Or do the planning people keep records? It's at least twenty years old.

With the current cost of building work, I am trying to limit the amount of building we do and thought adding to what we have may be a cost effective option. If anyone has any thoughts on this too I'd be grateful.

Thank you in advance.

I am fairly sure if you got a groundworker they would be able to dig down and tell you how deep the foundation is and therefore if it is deep enough to support a double storey

Amazing thank you. I'm sure I'll find all the details as soon as I've got someone out.

You will need the lintels over the ground floor windows checked as well to see if they can carry an extra storey of masonry. It's unlikely that that the roof joists will be sufficient to carry floor loading from above, so you can either replace them or interleave new ones so you don't disturb the ceiling below.

Thank you this is helpful.