Orientation of twin-wall polycarbonate sheets

General Gardening
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Currently in the middle of converting an old shed to a greenhouse. There’s already a solid existing wooden frame and concreate pad with electrical and water plus it has good sun exposure, so even if the layout isn’t ideal it’s too good to tear down and start fresh. I’m replacing the roof with polycarbonate and then cutting out some large “windows”, replacing sections of the wood siding with polycarbonate sheets.

Because of the dimensions I’m working with it’d be much simpler to mount the window panels in a horizontal orientation rather than vertical. All the manufacturers recommend mounting the panels vertically so that dirt and condensation doesn’t accumulate in the “flutes”. But I’m considering doing it horizontally anyway because I’ll have the open ends taped up and on top of that I’ll have some wooden slats covering the edges where the polycarbonate sheets meet the siding edge-to-edge. (kind of like a window frame). Anyone done something similar? Terrible idea or can I get away with it?

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What kind of tape will you be using on the ends? Usually it’s solid on top and perforated on the bottom.

There’s a reason for the recommendations. It hasn’t worked out well at times in the past.

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Yeah that’s what I did for the sloped roof panels. I was thinking that some amount of ventilation would be good for the windows as well, because some tiny amount of moisture creeping in is almost inevitable. So I’d use the vented tape on at least one side.

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I wonder what would happen if they were sealed on the ends? Say with silicone caulk. If nothing can get inside why won’t they stay clean? Not recommending that just wondering.

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If I could get it completely sealed that’d be ideal, I agree. Not sure how best to do that though with differential expansion/contraction from baking summer heat into freezing winters.

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