We are due to complete next week on a house we offered on in October. As the house has been unoccupied for at least 9 months, and the past few weeks have been bitterly cold here, we asked for a viewing today to check that no pipes had burst etc. Luckily, none had, but a crack has appeared in the plaster of the bedroom on the gable end, extending down in to the dining room below. It almost certainly wasn't there when we last viewed, and it's not mentioned in the survey carried out in November. Googling suggests it's penetrating damp, which should be reasonably easy to fix, and may not have happened if the house had been kept warm over winter. Any advice on what to do (apart from renegotiate), and whether my assumption is correct please?