ticki2 wrote:
Jfet wrote:
Steve, very nice job on your aluminum roof. I am now unsure if I want to go aluminum though. I see you used a vapor barrier under the aluminum (smart) but this would not allow me to sikaflex the aluminum directly to the marine plywood. Perhaps TPO or that other EPDM? stuff would be the better way to go for me, so I can bond it to the plywood that is screwed/glued to the metal roof joists.
Hmmm...
There would be no need for a vapor barrier between the aluminum and plywood , the aluminum , especially if one sheet , is in effect a vapor barrier . Add to this that is the wrong placement of a vapor barrier which should be on the inside wall ( warm side of insulation ) it becomes a negative . On a TC which usually has an impervious material as an outside skin I question if a vapor barrier should be used at all , even on the inside . Some how the wall has to breath or condensation will be trapped and eventually cause problems . Unless of course you can vacuum seal it or fill it with gas as in thermal windows , but I doubt that is practical .
True - there was probably no need to install any sort of barrier there. I wasn't originally going to, but then someone mentioned it so I thought it would do no harm. My logic being that because I am using quite thick aluminum I cannot guarantee to get it completely flat against the plywood (especially once it deforms slightly under the heat of welding). I don't live in the driest of places and so some humidity was likely to be sealed into that slight air gap. It occurred to me that when the temperature drops towards freezing point that humidity would condense on the underside of the aluminum, then run down to the lowest point and soak into the plywood. This barrier was an attempt to keep it off the plywood.
If you are using thin aluminum that you can glue directly to the plywood you wouldn't have this worry.
Note another thing I was careful about was keeping the aluminum electrically isolated from any steel components to avoid corrosion.
Keep up the good work - I'm following what you are doing with keen interest.
Steve.
