Oh KKOB - wasp nests vary in size from a tennis ball up to a football but even a large one will burn through and go out in about 10 seconds. Spraying the nest first as I suggest will make it burn even quicker) which is far too quick for surrounding material to reach combustion temperatures unless of course his wall is highly flammable. I've burned many wasp nests in the past without a single problem or even a sting (I'm a fast runner) , the last one being in May in a shrub in the garden of my apartment so there's no real need for the fire brigade, a video camera or your ill informed comments.