Sealing double wall polycarbonate after the fact

Discussion in 'Greenhouse Gardening' started by MoonShadows, Aug 6, 2017.

  1. MoonShadows

    MoonShadows

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    After a year of using my greenhouse as nothing more than an expensive seed starter, I want to learn about getting an earlier start and extending the season longer. From what I have read, this will entail sealing any leaks, insulating, an alternative heat source and a few other things, but before I begin, I realize I have one major obstacle which if I can't rectify is going to put a real crimp in my efforts.

    We bought and assembled a Sunshine Gardenhouse Mt. Rainier 8 x 16 redwood and double wall polycarbonate greenhouse. Today, I was looking at some YouTube vids and learned that if the ends of the polycarbonate panels are not sealed off, there is no air lock and therefore no dead space to help the insulating factor. My problem is it appears my polycarbonate panels are "floating" (for expansion/contraction) in the redwood frames, but they were never sealed at the ends! (Seems like a poor design to me.)

    My question...if I spend a small fortune on silicone caulking (most of which I'll wind up wearing like my friend @tbendl ) and I caulk around each panel both inside and outside, will the silicone caulking allow for enough expansion/contraction AND act as a seal to keep dead air in the panels? Seams to me it would, but want to bounce it off some others first. Thanks!
     
    MoonShadows, Aug 6, 2017
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  2. MoonShadows

    headfullofbees

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    Yes, silicone is both air and waterproof, but I'd use the mould-resistant bathroom type.
     
    headfullofbees, Aug 7, 2017
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    alp and MoonShadows like this.
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  3. MoonShadows

    MoonShadows

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    Thanks. I plan to use the clear elastomeric silicone caulking for best expansion/contraction give. I spoke with the maker of my greenhouse, and they don't recommend caulking both sides because it might affect the expansion/contraction. I think I will just caulk the inside to cut down on any leaks, not worry about sealing both sides, and use Reflectix insulation...double reflective, double bubble insulation...on the north and east walls and clear bubble wrap on the east and west walls. I also think I am also only going to insulate 1/2 the greenhouse to see how it goes this first year. I will also use 5 gallon buckets painted black and filled with water as a heat sink in addition to the already existing 8 inches of gravel on the floor that I laid slate over. I have a small oil-filled electric heater for colder days/nights.

    Any feedback is appreciated.

    716511516014.jpg
    double reflective, double bubble for east and north walls

    vent-bubble-sm.jpg
    clear for south and west walls
     
    MoonShadows, Aug 9, 2017
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