We have just moved into a 1901 semi-detached house and all seemed well until the central heating was turned on about 2 weeks ago. I noticed large patches of mould and peeling wallpaper in the upper corners and ceiling of the upstairs main bedroom. The ceiling has polystyrene tiles and they also seem to have a dusting of mould. I have checked in the attic for signs of water penetration but have noticed a white powdery substance on the bricks of the external wall in the attic. It looks like snow flakes or frosted ice. Is this dry rot? I have noticed no air bricks in the attic and the insulation in the loft is woeful. Would re-isulating the loft help or compound these problems. I think it is due to condensation and lack of ventilation. If so, what should I address first? Would ventillating the loft help the bedrooms? If there is dry rot on the bricks will they need replaced or can they be salvaged? As funds are limited, I would like a solution which provides the maximum benefit whilst the others can wait. Thanks.