i have a walk in chicken shed... and used a big blowtorch on a pipe and gas bottle, i used it and was overcome with smoke i couldnt see. my advice is make sure you dont do it alone and know where the door is, and have the hosepippe running..... with a little shed its easy just stick the torch in at arms lenght and stay outside, a quick flash over the wood kills everything.......... i now reach in as the torch has a long handle, and burn everything inc floor bedding and nest stuff.... its no good singing the wood and leaving live stuff in the bedding, you could get the bedding etc just outside the door first, then wet everything down a bit........... i think on balance this is better than napon.... its also good for singeing down off a plucked duck or goose.