I have just had my frame erected and was then told by the company that I was to board the inside of the external walls in order to provide racking as designed by their engineer. This at my own cost (probably over 1k so not bank breaking). Their defence is that my architect had the drawings with this detail on and he had signed it off. My architect was only employed by me to do the drawings not sign anything off, but out of his own steam he has been working alongside us. the frame company didn't give us any drawings to check or agree to other than our quote (our fault clearly, with hindsight). there have been other snags that I have absorbed but have decided to put my foot down on this one. My question is should I persist in saying it is their responsibility?