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Greenhouse design question: condensation

Discussion in 'Growing Areas' started by Marni, Mar 30, 2014.

  1. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I am in the early stages of designing a new greenhouse. In one of my current greenhouses the roof is double wall polycarbonates and I occasionally get a few condensation drips. Not a lot, but enough that I don't want it to happen again if I can avoid it. I am considering using triple wall for the roof of the new greenhouse. Can anyone tell me if I would be likely to have condensation with the triple wall? Also, is there degree of slope where the condensation will all run down rather than having a stray drip here or there?
     
  2. Ray

    Ray Orchid Iconoclast Supporting Member

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    Hi Marni.

    Triple-wall polycarbonate should increase the temperature gradient a little - that inner cell being slightly warmer than the outer one - but I really doubt it would significantly affect condensation..

    The angle question is like orchid-growing in general - it depends. Certainly, a steeper roof will lead to more runoff and less drippage, but that angle depends upon the surface energy of the material itself plus whatever coatings or residual processing aids happen to adhere to that interior surface. There are anti-drip polycarbonates available, but you can spray the interior with a surfactant periodically, too. I'm surprised there aren't any commercial products for that, but a soap solution would work, albeit temporarily.
     
  3. Reyna

    Reyna Orchid Obsessed Supporting Member

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    Wish I had good advice on this one. Let us know what you decide and how it works.
     
  4. KellyW

    KellyW Orchid wonk Staff Member Supporting Member

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    I wish I had an answer because I have the same problem. I staple plastic sheeting to the under-side of my 2x4 rafters to create a 3-1/2 inch dead air space. It works but is a pain to replace every few years.
     
  5. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Thanks, Ray, for the input.

    Kelly, I have inner lining on 1 of mine. If you get the UV resistant plastic sheet from greenhouse supply, it will last for many years. I'm still investigating a lot of things right now as I try to figure out the best roof for the restrictions I have.
     
  6. seidenfaden

    seidenfaden Well-Known Member

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    I also have had problems with condensation on the inside of the roof in my greenhouse. On the roof outside I have double walled polycabonate, inside bubble-wrap. I suppose the temperatures drops a lot colder in our climate in the northern part of the Uk than in California.
    However I have found that a fan or two blowing along the surface on the inside of the roof helps to avoid most of tte condensation.

    This summer I will be placing 15mm triple polycarbonate panels on the insideof the greennhouse..