Foundation checking / extensions on potential property - bit stressed

[OneArepa]

It’s me getting a bit stressed. Haven’t seen anything to indicate the house is stressed…

Have had an offer accepted on a property that has already been extended at the rear on the ground floor only. We’d want to extend the first floor at the rear.

If we have to pull down the existing extension, dig deeper footings to support two storeys and start from scratch, the cost potentially becomes an issue.

There’s no historical planning application showing the date of the original extension so may have been a PD job. Historical satellite pics indicate pre-1999.

Footings are going to be too shallow, aren’t they? What are our options to be sure - is there a level of survey that could check the existing footings? Have we got any other way of ascertaining this before completion?

Sorry if I’m missing something obvious. Bit sick, quite stressed and v tired.

We had to expose the corners of the extension until we hit the bottom. They were the same depth as the house (2 WTF metres) so we were fine to go ahead. If it is a recent extension, ie 1990 onwards the footings should be to the same standard as a new build, ie dig down to rock or pile drive etc. ours definitely were....can't ever see it moving!

Digging out though is a pig as avoiding making a massive hole, you need to do a lot by hand

@MarieG10
2m is deep for residential foundations. I can assure you that is not standard for new builds. However it shows the depth was needed for a reason. We have them at 2m on an extension due to the proximity of a tree and clay soil. Most houses don’t need 2m.
There is no rock! We are clay cap on chalk. Most houses don’t have rock near the surface. Residential foundations are rarely piled! It’s rarely necessary. It is expensive. Piles are usually used for large buildings and where soil is unstable.

@OneArepa thank you, that's really helpful. Is that the cost for your second storey over the first storey? Can I be cheeky and ask roughly how big it is? So hard to know what's a reasonable cost at the moment as everything has escalated so much since we last did any work!