Originally Posted by farok
Thanks. That wasn't what I was hoping to hear... I think I'll cover everything with 1/4" foam board, glued to the ribs and existing foam boards. Any gaps can then be filled with canned spray foam, preventing anything from getting behind it.
Seem like a feasible option?
Brokedown is partially right, catalytic propane heaters (is this the style you have?) are known for promoting humidity and/or condensation. But condensation can/will happen with or without a catalytic heater, the human body is another primary contributor to humidity in a small enclosed space, and the air naturally has some amount of water in it (humidity). This is why even in a ten with no heat source, condensation still forms overnight in cold conditions.
Condensation is the product of the difference in temperature between the inside air temperature and the temperature of a surface (exterior walls in this case), and the humidity of the air. Air's capacity to hold moisture diminishes as it gets colder (this is known as the 'dew point') and the temperature difference inside and outside tents to become more pronounced in colder weather which is why condensation is much more of a problem in cold weather. Humid air will 'condense' on a colder surface pulling water vapor out of the air and turning it to liquid water on the cold surface.
I see two major ways to address this problem, find ways to minimize the humidity of the interior air (crossventilation, choosing a heater that doesn't contribute to humidity or ideally pulls humidity out of the air), or find ways to minimize the difference in temperature between the inside of your exterior walls and the interior air (insulate! with a closed cell insulation). I don't know if 1/4 foam will be enough to do the job but its certainly a step in the right direction and should be a helluva lot better than nothing.
Let us know how it work out for you!