Greenhouse: GreenHouse Condensation, 1 by Horseshoe

Horseshoe wrote:
I don't believe you'll run into into bigtime problems with condensation if you keep in mind just a couple things. Your double-glazing will certainly help restrict condensation, so that's a big plus! The amount of heat inside the g-house vs the cold temperature outside plays a big role...condensation, of course, will form where there is the two temp differences.

Lack of air-movement inside the g-house combined with excessive watering of the plants will also be a big factor. I keep a small fan running all the time in my g-house; this not only inhibits dead air pockets but greatly reduces foliage disease and certain insect families.

Another factor that comes into play will be how much you are watering your plants. Excessive watering of the plants will also contribute to condensation, especially in Winter (due to Winter air usually being "dry air"). Excessive water in the g-house (especially to the point of soaking into the ground/floor) will do what water prefers to do, i.e., "seek its own level"...this means it will move into the (drier/warmer) air and when the air is saturated then you'll have water particulates (condensation). Restricting the over-use of water will definitely not only reduce the chance of condensation but will offer benefit to your plants as well (too much water during a slow-growth time is not healthy).

Before I continue on in this long-winded post, lemme just mention one last perspective...you mentioned that "I plan for extending growing season so it would be heated as needed". "Extending the season" usually refers to trying to get another couple weeks or months at one or both ends of the growing period (starting earlier in the Spring and growing past frost/freeze date in the Fall/Winter). If that is your goal, as opposed to using the g-house to over-winter plants all Winter, then the only thing you'll really need to do is ventilate your g-house during days when the sun is really heating it up (either lower your curtains or open doors,or have exhaust fans kick in. The hotter it gets in there (and yep, you'll see how warm they can get inside even if the temp outside is in the teens) the more moisture created (picture a terrarium).

Hope this has been helpful and NOT confusing. (By the way, am curious about what you are going to grow in there. I'm the curios sort, ya know!)

I have no idea what the pitch of this gh roof is, but in the pic you can see the angle of the ribs. I've seen very little condensation over the years and the few times I've witnessed it it was as someone above said (Stress baby?), the little bit of moisture collected on the metal ribs and dropped from there, not so much from the plastic glazing.