does house owner hae to prove extension is up to spec?

[drummergirl34]

Who's reponsible for proving that a house extension is up to spec? The house owner, or the buyer via a surveyor?

The home owner should be able to provide evidence that the extension has passed building regs.

Yes as shoe says above, we have an envelope filed with the details of our extension with the planning permission info, building regs and electrical safety certificate etc for us to prove its all above board when we sell.

It will depend how long ago the extension was done

If a recent extension yes via building regs etc

However a Victorian bedroom wing addition or 1950's kitchen bolt on extension will be a different matter, in those cases your surveyor is the person to deal with things

thanks, i'll speak to the owner and ask for proof!

Well, the owner doesn't have to prove anything, it depends whether the buyer or their mortgage company insist, and even then it depends if they want to sell to that buyer.
But as above you'd expect them to be able to provide evidence especially if they did it relatively recently.
At the end of the day it's your decision whether to buy based on the best evidence available.
The cheaper way to get evidence is from the seller, but you can get various inspections done that you can try to persuade them to pay for.
Good luck!

Via your surveyor. Don't trust the owner unless they have all up to date info as mentioned above and especially details of foundations and how the extension is knitted into the existing house and calcs for load bearing walls etc.