Extension questions...

[227lears]

I have an existing extension to the side of my property, housing the downstairs bathrrom and an additional dining room, this was built probably 25 odd years ago, roughly 15 years before we moved here. what i want to know is, can i build on top of the existing structure, or do i need to knock it down and start from scratch, the previous owner has no idea who built it, so can't vouch as to whether or not it would support the additional weight. would my local council still be in possesion of the plans, and if so can i look at them for free, and finally, what if the original plans wern't adhered to, what if the builder cut corners and didn't actually build it to the spec' submitted, making the bottom half of the extension unsafe.
Sorry if this is a bit of a mindful, but any help would be greatly appreciated.

 

[sbastiman]

Assuming you don't have/can't get the plans the best idea would be to get a Structural Surveyor in to look at the work and tell you where you stand ~ after that answers to the rest of your questions will fall into place.