We have already been consulted. We gave them the wrong answer, but luckily we have been corrected.
In summary "we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know."

Indeed how could the refurbish project go ahead with such uncertainties.

And in this spirit I'm currently refusing to re grout the tiles in my bathroom - who knows what I might find - the only answer is to demolish the room, start again and sell the garden and living room to pay for it.