Hi, I recently purchased a geodesic dome (built in 1980). A friend told me that moisture can build up between the drywall and roof sheeting (where the insulation is) due to the lack of roof vents, which can lead to rotting roof joists (sorry, I'm not sure if the proper term is "joists" for a dome). I understand that the interior/exterior temperature differential can pull moisture into this space but I have not yet seen a picture of a dome with roof vents. Essentially, I imagine every triangle on the roof would need an independent vent to be effective. Any thoughts? thanks!

My wife and I live in a Natural Spaces Dome that we built 30+ years ago. Our particular dome uses 2 X 10 struts insulated with 8" attic blanket. That leaves a bit over an inch of space between the insulation and the sheathing. This space is vented continuously from vents in the vertical sheathing below the base triangles all the way to the top of the dome. I built a structure tht covers the pentagon formed by the top 5 triangles and have this well ventilated to the outside. The system has seemed to work well so far.

Check out the Natural Spaces web site or contact me through IM if you would like more information.

Hugh

Lucas,
Before you get all wound up, the structure is 34 years old. More than likely, if you were having moisture issues, they would have shown up a long time ago. If you are worried about it, take the topmost part of the ceiling and cut a couple of 4 inch squares out of the drywall and find out if it is wet and or getting punky. Check the sheathing also. Then patch the holes carefully and go get a beer.
Alternatively, you can get someone with a moisture meter, probably a combo pin/survey type with extra long probes. I use a Protimeter SurveyMaster (BLD5365). That would give you a sense of what the conditions were right now, but might not get at seasonal buildup of moisture. A thermal imager may or may not pick up any signs of moisture variations in the wall.
When the structure was re roofed, was any plywood replaced? That would be a dead giveaway.
Cheers,
Eric