kmillar wrote:
How safe is it to use a blow torch in this confined space? (About 18
inches of verticle space benathe the floors). Apart from the obvious
need to not set the house on fire, I'm more interested in the fumes
given off by the blow lamp. What can I do about those?

It'll be fine. It's not, or rather shouldn't be, a source of carbon
monoxide, and you won't need it on for long, anyway. Take care that hot
flux or solder doesn't drip on you.