A mate of mine was a great user of a blow torch in the lofts. Cleaned the stock birds one day, ( they were at his parents' farm) and gave it a go over with the blow torch, as he had done for years, then a misting of Virkon. That night he was called by his mother to come quickly, the loft was on fire !! In the couple of minutes it took him to drive down the road the loft was ablaze when he arrived.....nothing survived. Afterwards he thought the only explanation was that some 'hidden' dust/feathers must have smouldered and later turned into a small flame, which went on to engulf the loft. He was totally gutted at the time....hasn't used a blow torch since, and never will again. Not my idea either, simply wouldn't take the chance.