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I don't know if this is the right forum to ask this but this seemed most related.

So is there a breathable (allows moisture escape but doesn't allow water, CO2 or air to pass through) fabric-film available to use as greenhouse cover?

Humidity is huge problem for greenhouses, especially in Hot climates, which are cooled by evaporative cooling. If a breathable material with high transparency is available, it will solve the humidity problem due to high partial pressure of vapor inside than outside.

Tyvac is breathable, but has just 6-8% light transmittance and won't withstand direct sunlight for very long. Also, moisture permeability should be very high (about 500 ml/ hour x square meter) and I don't think even Tyvac can handle that.

Milind Patel
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  • How can it be breathable if air can't pass through? And moisture is water – Graham Chiu Feb 04 '18 at 18:46
  • "Breathable" is the word Air Barrier industry uses. Yes, Liquid water should not pass, Moisture should pass, Any other gases should not pass. Tyvac is one such material, but it's not transparent. "HouseWrap" is class of materials with this moisture permeable but air impermeable type membranes. – Milind Patel Feb 04 '18 at 19:54
  • You are interpreting the product literature incorrectly. "Any other gasses should not pass" is complete and utter delusion. The material stops bulk air movement but is quite gas permeable. Also, it's Tyvek (correct spelling.) If you really want to spend a lot more than proper ventilation will cost you I suppose you could look into Gore-Tex. – Ecnerwal Feb 04 '18 at 21:08
  • "complete and utter" mean same things, IMO. Delusion? Nope. Misunderstanding, may be. Anyways, I kept on searching and I came across TPU (Thermoplastic PolyUrethan) monolithic films which have high permeability to moisture but not other components of Air. They have been used as greenhouse glazing as well. Posted so anyone else wondering the same does get a starting point. FWIW, moisture permeability was important point of my question and I shouldn't have sought "Tyvek" like materials. But I didn't know even monolithic films can be so much permeable. – Milind Patel Feb 09 '18 at 20:08

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